Biol 1202 - Exam 4

Front 1

Chapter 40:

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Basic Principles of Animal Form and Function

Front 2

Animals as different as hydras, halibut, and humans must:

Back 2

Obtain oxygen, nourish themselves, excrete waste products, and move

Front 3

A structural adaptation for feeding serving as a straw through which the moth can suck nectar from deep within tube-shaped flowers.

Back 3

Extended proboscis

Front 4

The study of the structure of an organism

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Anatomy

Front 5

The study of the functions of an organism

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Physiology

Front 6

How organisms obtain, process, and use their energy resources

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Bioenergetics

Front 7

Concept 40.1:

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Physical laws and the environment constrain animal size and shape

Front 8

__________ requirements constrain what natural selection can "invent," including the size and shape of the flying animals

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Physical

Front 9

This occurs because natural selection shapes similar adaptations when diverse organisms face the same environmental challenge, such as the resistance of water to fast travel.

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Convergence

Front 10

An animal's size and shape have a direct effect on how the animal _________ energy and materials with its surroundings.

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Exchanges

Front 11

Occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells' plasma membranes. As shown, a single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm

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Exchange with the environment

Front 12

Figure 40.3: Contact with the environment

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(a) In a unicellular protist, such as the amoeba, the entire surface area contacts the environment.
(b) A hydra's body consists of two layers of cells. Because the aqueous environment can circulate in and out of the hydra's mouth, virtually every one of its cells directly contacts the environment and exchanges materials with it

Front 13

Figure 40.4: Internal exchange surfaces of complex animals.

Back 13

The lining of the small intestine, a digestive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption.

A microscropic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment.

Inside a kidney is a mass of microscopic tubules that exchange chemicals with blood flowing through a web of tiny vessels called capillaries.

This diagrammatic animal illustrates the logistics of chemical exchange with the environment by a mammal. Most animals have surfaces that are specialized for exchanging certain chemicals with the surroundings. These exchange surfaces are usually internal, but are connected to the environment via openings on the body surface (the mouth, for example). The exchange surfaces are finely branched or folded, giving them a very large area. The digestive, respiratory, and excretory systems all have such exchange surfaces. Chemicals transported across these surfaces are carried throughout the body by the circulatory system.

Front 14

How does a large surface area contribute to the functions of the small intestine, the lungs, and the kidneys?

Back 14

The small intestine, the lungs, and the kidneys contain internal exchange surfaces through which nutrients, gases, and chemicals, respectively, flow. A large surface area facilitates this exchange and enables the body to carry out the exchange more efficiently than if there were less surface area available

Front 15

Concept 40.2:

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Animal form and function are correlated at all levels of organization

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Are groups of cells with a common structure and function

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Tissues

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Tissues are classified into four main categories:

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Epithelial, connective, muscle, and nervous

Front 18

Occurring in sheets of tightly packed cells, ___________ covers the outside of the body and lines organs and cavities within the body

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Epithelial tissue

Front 19

This tight packing enables the epithelium to function as a barrier against mechanical injury, microbes, and fluid loss. Some epithelia, called __________, absorb or secrete chemical solutions

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Glandular epithelia

Front 20

The glandular epithelia that line the lumen (cavity) of the digestive and respiratory tracts form a ______________; they secrete mucus that lubricates the surface and keeps it moist.

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Mucous membrane

Front 21

Two criteria for classifying epithelia are:

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Number of cell layers and shape of the cells on the exposed surface.

Front 22

Has a single layer of cells

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Simple epithelia

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Has multiple tiers of cells.

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Stratified epithelia

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Is single-layered but appears stratified because the cells vary in length

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Pseudostratified

Front 25

The shape of the cells at the exposed surfaces may be:

Back 25

Cuboidal (like dice)
Columnar (like bricks standing on end)
Squamous (like floor tiles)

Front 26

Functions mainly to bind and support other tissues.

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Connective tissue

Front 27

Connective tissue fibers, which are made of protein, are of three kinds:

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Collagenous fibers, elastic fibers, and reticular fibers

Front 28

Are made of collagen, probably the most abundant protein in the animal kingdom.

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Collagenous fibers

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Are long threads made of a protein called elastin.

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Elastic fibers

Front 30

Are very thin and branched.

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Reticular fibers

Front 31

The major types of connective tissue in vertebrates are:

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Loose connective tissue, adipose tissue, fibrous connective tissue, cartilage, bone, and blood

Front 32

Among the cells scattered in loose connective tissue, two types predominate:

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Fibroblast and macrophages

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Secrete the protein ingredients of the extracellular fibers.

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Fibroblasts

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Are amoeboid cells that roam the maze of fibers, engulfing foreign particles and the debris of dead cells by phagocytosis.

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Macrophages

Front 35

Is composed of long cells called muscle fibers that are capable of contracting, usually when stimulated by nerve signal.

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Muscle tissue

Front 36

________ is the most abundant tissue in most animals, and muscle contraction accounts for much of the energy-consuming cellular work in an active animal.

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Muscle

Front 37

Senses stimuli and transmits signals in the form of nerve impulses from one part of the animal to another.

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Nervous tissue

Front 38

The functional unit of nervous tissue is the ______, or nerve cell.

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Neuron

Front 39

Figure 40.5:

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Exploring Structure and Function in Animal Tissues

Front 40

Lines the inner surface of the urethra, the tube through which urine exits the body

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Stratified columnar epithelium

Front 41

Lines the intestines, this epithelium secretes digestive juices and absorbs nutrients

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Simple columnar epithelium

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Forms a mucous membrane that lines the respiratory tract of many vertebrates. The beating cilia move a film of mucus along the surface. The ciliated epithelium of respiratory tubes helps keep lungs clean by trapping dust and other particles and sweeping them back up the trachea (windpipe).

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Pseudostratified ciliated columnar epithelium

Front 43

With cells specialized for secretion, make up the epithelia of kidney tubules and many glands, including the thyroid gland and salivary glands. Glandular epithelia lining tubules in the thyroid gland secrete a hormone that regulates the body's rate of fuel consumption.

Back 43

Cuboidal epithelia

Front 44

Which are thin and leaky, function in the exchange of material by diffusion. These epithelia line blood vessels and the air sacs of the lungs, where diffusion of nutrients and gases is critical.

Back 44

Simple, squamous epithelia

Front 45

Regenerate rapidly by cell division near the basement membrane. The new cells are pushed to the free surface as replacements for cells that are continually sloughed off. This types of epithelium is commonly found on surfaces subject to abrasion, such as the outer skin and linings of the esophagus, anus, and vagina. The organization of this type of tissue ensures that abrasion affects the oldest (outermost) cells, while protecting underlying tissues.

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Stratified squamous epithelia

Front 46

The cells at the base of an epithelial layer are attached to a _____________, a dense mat of extracellular matrix. The free surface of the epithelium is exposed to air or fluid.

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Basement membrane

Front 47

The most widespread connective tissue in the vertebrate body is ___________________. It binds epithelia to underlying tissues and functions as "packing material," holding organs in place. Loose connective tissue gets its name from the loose weave of its fibers, which include all three fiber types: collagenous, elastic, and reticular. Fibroblasts and macrophages are scattered in the fibrous mesh.

Back 47

Loose connective tissue

Front 48

Is dense, owing to its large number of collagenous fibers. The fibers are organized into parallel bundles, an arrangement that maximizes nonelastic strength. Fibrous connective tissue is found in tendons, which attach muscles to bones, and in ligaments, which join bones together at joints.

Back 48

Fibrous connective tissue

Front 49

__________ has an abundance of collagenous fibers embedded in a rubbery matrix made of a protein-carbohydrate complex called chondroitin sulfate. Chondroitin sulfate and collagen are secreted by cells called ____________ the composite of collagenous fibers and chondroitin sulfate makes cartilage a strong yet somewhat flexible support material. Many vertebrates have cartilaginous skeletons during the embryo stage, but most of the cartilage is replaced by bone as the embryo matures. Nevertheless, cartilage is retained in certain locations, such as the discs that act as cushions between vertebrae and the caps on the ends of some bones. These structures' flexibility allows them to absorb considerably physical impact without breaking.

Back 49

Cartilage; chondrocytes

Front 50

Is a specialized form of loose connective tissue that stores fat in adipose cells distributed throughout its matrix. Adipose tissue pads and insulates the body and stores fuel as fat molecules. Each adipose cell contains a large fat droplet that swells when fat is stored and shrinks when the body uses fat as fuel.

Back 50

Adipose tissue

Front 51

The skeleton supporting the body of most vertebrates is made of _____, a mineralized connective tissue.

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Bone

Front 52

Bone-forming cells called _________ deposit a matrix of collagen. Calcium, magnesium, and phosphate ions combine and harden within the matrix into the mineral hydroxyapatite. The combination of hard mineral and flexible collagen makes bone harder than cartilage without being brittle, an important characteristic for supporting the body.

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Osteoblasts

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The microscopic structure of hard mammalian bone consists of repeated units called _______ or Haversian systems. Each has concentric layers of the mineralized matrix, which are deposited around a central canal containing blood vessels and nerves that service the bone.

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Osteons

Front 54

Although _______ functions differently from other connective tissues, it does meet the criterion of having an extensive extracellular matrix. In this case, the matrix is a liquid called plasma, consisting of water, salts, and a variety of dissolved proteins. Suspended in the plasma are two classes of blood cells, erythrocytes (red blood cells) and leukocytes (white blood cells), and cell fragments called platelets. Red cells carry oxygen; white cells function in defense against viruses, bacteria, and other invaders; and platelets aid in blood clotting. The liquid matrix enables rapid transport of blood cells, nutrients, and wastes through the body.

Back 54

Blood

Front 55

Attached to bones by tendons, _________ is responsible for voluntary movements of the body.

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Skeletal muscle

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Skeletal muscle consists of bundles of long cells called ________, each of these is a bundle of strands called myofibrils.

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Fiber

Front 57

The arrangement of contractile units, or ___________, along the length of the fibers gives the cells a striped (striated) appearance under the microscope.

Back 57

Sarcomeres

Front 58

For this reason, skeletal muscle is called _________.

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Striated muscle

Front 59

Adult mammals have a fixed number of muscles cells; building muscle does not increase the number but rather ____ those already present.

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Enlarges

Front 60

_________, so named because it lacks striations, is found in the walls of the digestive tract, urinary bladder, arteries, and other internal organs. The cells are spindle-shaped. They contract more slowly than skeletal muscle cells but can remain contracted longer. Controlled by different kinds of nerves that those controlling skeletal muscles, smooth muscles are responsible for involuntary body activities, such as churning of the stomach or constriction of arteries.

Back 60

Smooth muscle

Front 61

__________ forms the contractile wall of the heart. It is striated like skeletal muscle and has contractile properties similar to those of skeletal muscle. Unlike skeletal muscle, however, this muscle carries out an unconscious task: contraction of the heart. Its fibers branch and interconnect via intercalated disks, which relay signals from cell to cell and help synchronize the heartbeat.

Back 61

Cardiac muscle

Front 62

Nerve cells (neurons) are the basic units of the nervous system. A ______ consists of a cell body and two or more extensions, or processes, called dendrites and axons, which in certain neurons may be as long as a meter in some animals.

Back 62

Neuron

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Carry information from their tips toward the rest of the neuron.

Back 63

Dendrites

Front 64

Transmit impulses toward another neuron or toward an effector, a structure such as a muscle cell that carries out a body response.

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Axons

Front 65

The long axons of motor neurons enable quick responses by _______ muscles.

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Voluntary

Front 66

Table 40.1: Organ System: Their Main Components and Functions in Mammals

Back 66

1. Digestive: (mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, anus) - food processing (ingestion, digestion, absorption, elimination)

2. Circulatory: (heart, blood vessels, blood) - internal distribution of materials

3. Respiratory: (lungs, trachea, other breathing tubes) - gas exchange (uptake of oxygen; disposal of carbon dioxide)

4. Immune and lymphatic: (bone marrow, lymph nodes, thymus, spleen, lymph vessels, white blood cells) - body defense (fighting infections and cancer)

5. Excretory: (kidneys, ureters, urinary bladder, urethra) - disposal of metabolic wastes; regulation of osmotic balance of blood

6. Endocrine: (pituitary, thyroid, pancreas, other hormone-secreting glands) - coordination of body activities (such as digestion, metabolism)

7. Reproductive: (ovaries, testes, and associated organs) - reproduction

8. Nervous: (brain, spinal cord, nerves, sensory organs) - coordination of body activities; detection of stimuli and formulation of responses to them

9. Integumentary: (skin and its derivatives such as hair, claws, and skin glands) - body support, protection of internal organs, movement

10. Muscular: (skeletal muscles) - movement, locomotion

Front 67

In all but the simplest animals (sponges and other cnidarians), different tissues are organized into ______.

Back 67

Organs

Front 68

Many of the organs of vertebrates are suspended by sheets of connective tissue called __________ in moist or fluid-filled body cavities.

Back 68

Mesenteries

Front 69

Mammals have a ________ housing the lungs and heart that is separated from the lower abdominal cavity by a sheet of muscle called the diaphragm.

Back 69

Thoracic cavity

Front 70

Representing a level of organization higher than organs, ____________ carry out the major body functions of most animals.

Back 70

Organ systems

Front 71

Describe how the epithelial tissue that lines the stomach lumen is well suited to its function.

Back 71

The epithelium lining the inner surface of the stomach secrets mucus, which lubricates and protects the surface, and digestive juices. Also, the tight packing of the epithelial tissue serves as a protective barrier.

Front 72

Suggest why a disease that damages connective tissue is likely to threaten most of the body's organs.

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Connective tissue is an important part of most organs, and sheets of connective tissue support many of the body's organs

Front 73

How are muscle and nervous tissue interdependent?

Back 73

Both nervous tissue and muscle tissue are required to carry out responses to many stimuli. Skeletal muscle tissue contracts in response to nerve impulses transmitted by nerve cells.

Front 74

Concept 40.3:

Back 74

Animals use the chemical energy in food to sustain form and function

Front 75

All organisms require _______ energy for growth, repair, physiological processes (including movement in the case of animals), regulation, and reproduction.

Back 75

Chemical

Front 76

The flow of energy through an animal which ultimately limits the animal's behavior, growth, and reproduction and determines how much food it needs.

Back 76

Bioenergetics

Front 77

Animals harvest chemical energy from the food they eat: Process.

Back 77

Food is digested by enzymatic hydrolysis, and energy-containing molecules are absorbed by body cells. Once absorbed, these energy-containing molecules have several possible fates. Most are used to generate ATP by the catabolic processes of cellular respiration and fermentation. The chemical energy of ATP powers cellular work, enabling cells, organs, and organ systems to perform the many functions that keep an animal alive. Because the production and use of ATP generate heat, an animal continuously gives off heat to its surroundings.

After the energetic needs of staying alive are met, any remaining molecules from food can be used in biosynthesis, including body growth and repair, synthesis of storage material such as fat, and production of gametes.

Front 78

Figure 40.7:

Back 78

Bioenergetics of an animal: an overview. Pg. 828

Front 79

The amount of energy an animal uses in a unit of time is called its __________, the sum of all the energy-requiring biochemical reactions occurring over a given time interval.

Back 79

Metabolic rate

Front 80

Because nearly all the chemical energy used in cellular respiration eventually appears as heat, metabolic rate can be measured by monitoring an animal's rate of _________. Researchers can use a calorimeter, which is a closed, insulated chamber equipped with a device that records an animal's heat loss, to measure metabolic rate of small animals.

Back 80

Heat loss

Front 81

Birds and mammals are mainly ________, meaning their bodies are warmed mostly by heat generated by metabolism, and their body temperature is maintained within a relatively narrow range.

Back 81

Endothermic - it permits intense long-duration activity over a wide range of environmental temperatures

Front 82

Most fishes, amphibians, reptiles other than birds, and invertebrates are _______, meaning that they gain their heat mostly from external sources.

Back 82

Ectothermic - it requires a much smaller energy expenditure by an animal than the endothermic strategy because of the high energy cost of heat (or cooling) an endothermic body.

In general, endotherms have higher metabolic rates than ectotherms.

Front 83

The amount of energy it take to maintain each gram of body weight is _________ related to body size.

Back 83

Inversely

Front 84

The metabolic rate of a nongrowing endotherm that is at rest, has an empty stomach, and is not experiencing stress is called:

Back 84

Basal metabolic rate (BMR)

Front 85

Unlike BMRs, which can be determined within a range of environmental temperatures, the minimum metabolic rate of an ectotherm must be determined at a specific termperature.

The metabolic rate of a resting, fasting, nonstressed ectotherm at a particular temperature is called:

Back 85

Standard metabolic rate (SMR)

Front 86

Maximum metabolic rates, the highest rates of ___ utilization, occur during peak activity, such as lifting heavy weights, sprinting, or high-speed swimming

Back 86

ATP

Front 87

Figure 40.9: Maximum metabolic rates over different times spans.

Back 87

The bars compare an ectothemr (alligator) and an endotherm (human) for their maximum potential metabolic rates and ATP sources over different durations of time. The human's basal metabolic rate (about 1.2 kcal/min) is much greater than the alligator's standard metabolic rate (about 0.04 kcal/min). The human's higher BMR partly contributes to his ability to sustain a higher maximum metabolic rate over a longer period

Front 88

Figure 40.10: Energy budgets for four animals

Back 88

a.) Total annual energy expenditures: The slices of the pie charts indicate energy expenditures for various functions

b.) Energy expenditures per unit mass (kcal/kg x day). Comparing the daily energy expenditures per kg of body weight for the four animals reinforces two important concepts of bioenergetics. First, a small animal, such as a mouse, has a much greater energy demand per kg than does a large animal of the same taxonomic class, such as a human (both mammals). Second, note again that an ectotherm, such as a python, requires much less energy per kg than does an endotherm of equivalent size, such as a penguin.

Front 89

If a mouse and a small lizard of the same mass (both at rest) were placed in respirometers under identical environmental conditions, which animal would consume oxygen at a higher rate? Explain.

Back 89

The mouse, because it is an endotherm and therefore its basal metabolic rate is higher than the ectothermic lizard's standard metabolic rate.

Front 90

Why are alligators not capable of intense activity for periods of more than 1 hour?

Back 90

Intense activity quickly depletes existing ATP. Because alligators are ectotherms, they are relatively slow to generate more ATP by aerobic respiration

Front 91

Which must eat a larger proportion of its weight on food each day: a house cat or an African lion? Explain.

Back 91

The house cat; the small an animal, the higher its metabolic rate and its demand for food per unit of body mass

Front 92

Concept 40.4:

Back 92

Many animals regulate their internal environment within relatively narrow limits

Front 93

The internal environment of vertebrates is called this; this fluid which fills the spaces between vertebrate cells, exchanges nutrients and wastes with blood contained in microscopic vessels called capillaries.

Back 93

Interstitial fluid

Front 94

Bernard's "constant internal milieu" is incorporated into the concept of __________, which means "steady state" or internal balance.

Back 94

Homeostasis

Front 95

__________ is a dynamic state, an interplay between outside factors that tend to change the internal environment and internal control mechanisms that oppose such changes

Back 95

Homeostasis

Front 96

An animal is said to be a __________ for a particular environmental variable if it uses internal control mechanisms to moderate internal change in the face of external fluctuation.

Back 96

Regulator

Front 97

An animal is said to be a __________ for a particular environmental variable if it allows its internal condition to vary with certain external changes.

Back 97

Conformer

Front 98

Regulating and conforming represent extremes on a __________, and no organism is a perfect regulator or conformer. Furthermore, an animal may maintain homeostasis while regulating some internal conditions and allowing others to conform to the environment.

Back 98

Continuum

Front 99

Mechanisms of homeostasis moderate changes in the internal environment. Any homeostatic control system as three functional components:

Back 99

Receptor, control center, effector

Front 100

Detects a change in some variable of the animals' internal environment, such as change in body temperature

Back 100

Receptor

Front 101

Processes information it receives from the receptor and directs an appropriate response by the effector.

Back 101

Control center

Front 102

Control circuit that changes in the variable being monitored triggers the control mechanism to counteract further change in the same direction.

Back 102

Negative feedback

Front 103

Control circuit that involves a change in some variable that triggers mechanisms that amplify rather than reverse the change.

Back 103

Positive feedback

Front 104

Figure 40.11: A nonliving example of negative feedback - control of room temperature

Back 104

Regulating room temperature depends on a control center that detects temperature change and activates mechanisms that reverse that change. Pg. 832

Front 105

Does a regulator maintain a constant internal environment? Explain.

Back 105

No, even though an animal regulates some aspects of its internal environment, often by negative feedback mechanisms, the internal environment fluctuates slightly around a set point. Homeostasis is a dynamic state, and some change, such as radical increases in hormones at particular times in development, are programmed to occur.

Front 106

Describe the difference between negative feedback and positive feedback mechanisms.

Back 106

In negative feedback, a change triggers control mechanisms that counteract further change in that direction. In positive feedback, a change triggers mechanisms that amplify the change.

Front 107

Concept 40.5:

Back 107

Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior

Front 108

The process by which animals maintain an internal temperature within a tolerable range. This ability is critical to survival because most biochemical and physiological processes are very sensitive to changes in body temperature.

Back 108

Thermoregulation

Front 109

It is important to note that animals are NOT classified as ectotherms and endotherms based on whether they have variable or constant body temperatures; as mentioned, it is the _______ of heat used to maintain body temperature that distinguishes between them

Back 109

Source

Front 110

Being able to generate a large amount of heat metabolically, along with other biochemical and physiological adaptations associated with endothermy (such as elaborate circulatory and respiratory systems), enables endotherms to _______________ for much longer than is possible for most ectotherms.

Back 110

Perform vigorous activity

Front 111

Endotherms generally need to consume much _____ food than ecotherms of equivalent size - a serious disadvantage for endotherms if food supplies are limited. For this and other reasons, ectothermy is an extremely effective and successful strategy in most of Earth's environments, as shown by the abundance and diversity of ecothermic animals.

Back 111

More

Front 112

Whether it is an ectotherm or endotherm, an organism, like any object exchanges heat by four physical processes:

Back 112

Conduction, convection, radiation, and evaporation

Front 113

Figure 40.13: Heat exchange between an organism and its environment.

Back 113

Radiation: the emission of electromagnetic waves by all objects warmer than absolute zero. Radiation can transfer heat between objects that are not in direct contact, as when a lizard absorbs heat radiating from the sun

Evaporation: the removal of heat from the surface of a liquid that is losing some of its molecules as gas. Evaporation of water form a lizard's moist surfaces that are exposed to the environment has a strong cooling effect

Convection: the transfer of heat by the movement of air or liquid past a surface, as when as breeze contributes to heat loss from a lizard's dry skin, or blood moves heat from the body core to the extremities

Conduction: the direct transfer of thermal motion (heat) between molecules of objects in direct contact with each other, as when a lizard sits on a hot rock

Front 114

Figure 40.14: Mammalian integumentary system

Back 114

Epidermis, Dermis, Hypodermis. Pg. 835

Front 115

For endotherms and for those ectotherms that thermoregulate, the essence of thermoregulation is managing the head budget so that rates of heat gain are _______ to rates of heat loss.

Back 115

Equal

Front 116

A major thermoregulatory adaptation in mammals and birds is _______ (hair, feathers, or fat layers), which reduces the flow of heat between an animal and its environment and lowers the energy cost of keep warm.

Back 116

Insulation

Front 117

In mammals, the insulating material is associated with the _______, the outer covering of the body, consisting of the skin, hair, and nails (claws or hooves in some species). Skin is a key organ of this.

Back 117

Integumentary system

Front 118

The skin consists of two layers:

Back 118

The epidermis and dermis; underlain by a tissue layer called the hypodermis

Front 119

The outermost layer of skin and is composed mostly of dead epithelial cells that continually flake and fall off.

Back 119

Epidermis

Front 120

Supports the epidermis and contains hair follicles, oil and sweat glands, muscles, nerves, and blood vessels.

Back 120

Dermis

Front 121

Contains adipose tissue, which includes fat-storing cells and blood vessels.

Back 121

Hypodermis

Front 122

Marine mammals, such as whales and seals, have a very thick layer of insulating fat called _______, just under their skin

Back 122

Blubber

Front 123

Elevated blood flow in the skin normally results form _______, an increase in the diameter of superficial blood vessels (those near the body surface) triggered by nerve signals that relax the muscles of the vessel walls. In endotherms, this usually warms the skin, increasing the transfer of body heat to a cool environment by radiation, conduction, and convection.

Back 123

Vasodilation

Front 124

The reverse process, _______, reduces blood flow and heat transfer by decreasing the diameter of superficial vessels.

Back 124

Vasoconstriction

Front 125

Another circulatory adaptation is an arrangement of blood vessels called a _______ that is important for reducing heat loss in many endotherms, including marine mammals and birds.

Back 125

Countercurrent heat exchanger

Front 126

Figure 40.15: Countercurrent heat exchangers

Back 126

A countercurrent heat exchanger traps heat in the body core, thus reducing heat loss form the extremities, which are often immersed in cold water or in contact with ice or snow. In essence, heat in the arterial blood energy from the body core is transferred directly to the returning venous blood instead of being lost to the environment.

1.) Arteries carrying warm blood down the legs of a goose or the flippers of a dolphin are in close contact with veins conveying cool blood in the opposite direction, back toward the trunk of the bdoy. This arrangement facilitates heat transfer from arteries to veins (black arrows) along the entire length of the blood vessels

2.) Near the end of the leg or flipper, where arterial blood has been cooled to far below the animal's core temperature, the artery can still transfer heat to the even colder blood of an adjacent vein. The venous blood continues to absorb heat as it passes warmer and warmer arterial blood traveling in the opposite direction.

3.) As the venous blood approaches the center of the body, it is almost as warm as the body core, minimizing the heat loss as a result of supplying blood to body parts immersed in cold water.

In the flippers of a dolphin, each artery's surrounded by several veins in a countercurrent arrangement, allowing efficient heat exchange between arterial and venous blood.

Front 127

Figure 40.16: Thermoregulation in large, active bony fishes and sharks. Pg. 837

Back 127

a.) Bluefin tuna: Unlike most fishes, the bluefin tuna maintains temperatures in its main swimming muscles that are much higher than the temperature of the surrounding water (colors indicate swimming muscles cut in transverse section). These temperatures were recorded for a tuna in 19 degrees celsius.

b.) Great white shark: Like the bluefin tuna, the great white shark has a countercurrent heat exchanger in its swimming muscles that reduces the loss of metabolic heat. All bony fishes and sharks lose heat to the surrounding water when their blood passes through the gills. However, endothermic sharks have a small dorsal aorta, and as a result, relatively little cold blood from the gills goes directly to the core of the body. Instead, most of the blood leaving the gills is conveyed via large arteries just under the skin, keeping cool blood away from the body core. As shown in the enlargement, small arteries carrying cool blood inward from the large arteries under the skin are paralleled by small veins carrying warm blood outward from the body core. This countercurrent flow retains heat in the muscles.

Front 128

Figure 40.17: Internal temperature in the winter moth

Back 128

This infrared map shows the moth's heat distribution immediately after a flight. Red in the thorax region indicates the highest temperature. Moving outward, th variously colored zones correspond to regions of progressively lower body temperatures.

Front 129

If environmental temperature is above body temperature, animals gain heat from the environment as well as from metabolism, and _______ is the only way to keep body temperature form rising rapidly.

Back 129

Evaporation

Front 130

Sweating or bathing moistens the skin and enhances evaporative _______.

Back 130

Cooling

Front 131

In some mammals, certain hormones can cause mitochondria to increase their metabolic activity and produce heat instead of ATP. This _______ takes place throughout the body, but some mammals also have a tissue called brown fat in the next and between the shoulders that is specialized for rapid heat production. Through shivering and NST, mammals and birds in cold environments can increase their metabolic heat production by as much as five to ten times the minimal levels that occur in warm condition.

Back 131

Nonshivering thermogenesis (NST)

Front 132

Nerve cells that control thermoregulation, as well as those that control many other aspects of homeostasis, are concentrated in a region of the brain called:

Back 132

Hypothalamus

Front 133

The _______ contains a group of nerve cells that functions as a thermostat, responding to changes in body temperature above or below a set point (actually above or below a normal range) by activating mechanisms that promote heat loss or gain.

Back 133

Hypothalamus

Front 134

Figure 40.21: The thermostat function of the hypothalamus in human thermoregulation. Pg. 839

Back 134

Nerve cells that sense temperature are in the skin, in the hypothalamus itself, and in several other body regions. Warm receptors signal the hypothalamic thermostat when temperatures increase; cold receptors signal temperature decrease. At body temperatures below the normal range, the thermostat inhibits heat loss mechanisms and activates heat-saving ones such as vasoconstriction of superficial vessels and erection of fur, while stimulating heat-generating mechanisms (shivering and nonshivering thermogenesis). In response to elevated body temperature, the thermostat shuts down heat retention mechanisms and promotes body cooling by vasodilation, sweating, or panting. The thermostat can also respond to external temperature (sensed as skin temperature) even without changes in the body core temperature

Front 135

Many animals can adjust to a new range of environmental temperatures over a period of days or weeks, a physiological response called:

Back 135

Acclimatization

Front 136

In birds and mammals, acclimatization often includes adjusting the amount of _______ - by growing a thicker coat of fur in the winter and shedding it in the summer, for example - and sometimes varying the capacity for metabolic heat production in different seasons.

Back 136

Insulation

Front 137

_______ in ectotherms involves compensating for changes in temperature. These adjustments can strongly affect physiology and temperature tolerance.

Back 137

Acclimatization

Front 138

Acclimatization responses in ectotherms often include adjustments at the _______ level. Cells may increase the production of certain enzymes or produce variants of enzymes that have the same function but different optimal temperatures.

Back 138

Cellular

Front 139

Cells can often make rapid adjustments to temperature changes. For example, mammalian cells grown in lab cultures respond to marked increase in temperature and to other forms of severe stress by accumulating molecules called: _______ , including _______.

Back 139

Stress-induced proteins; heat-shock proteins

Front 140

These proteins help maintain the integrity of other proteins that would be denatured by severe heat.

Back 140

Heat-shock proteins

Front 141

Help prevent cell death when an organism is challenged by severe changes in the cellular environment.

Back 141

Stress-induced proteins

Front 142

An adaptation that enables animals to save energy while avoiding difficult and dangerous conditions is _______, a physiological state in which activity is low and metabolism decreases.

Back 142

Torpor

Front 143

Long-term torpor that is an adaptation to winter cold and food scarcity. When vertebrate endotherms (birds and mammals) enter torpor or hibernation, their body temps decline - in effect, their body's thermostat is turned down.

Back 143

Hibernation

Front 144

Summer torpor, also characterized by slow metabolism and inactivity, enables animals to survive long periods of high temperatures and scare water supplies. Hibernation and this are often triggered by seasonal changes in the length of daylight.

Back 144

Estivation

Front 145

Many small mammals and birds exhibit a _______ that seems to be adapted to their feeding patterns.

Back 145

Daily turpor

Front 146

Can ectotherms have stable body temperatures? Explain.

Back 146

Yes, ectotherms in the deep sea and in constant-temperature freshwater springs have constant body temperatures. And terrestrial ectotherms can maintain relatively constant body temperatures by behavioral means.

Front 147

What mode of heat exchange is involved in "wind chill," when moving air feels colder than still air at the same temperature?

Back 147

Heat loss through convection

Front 148

Some birds in tropical dry forests periodically go into torpor, especially in the dry season. Explain.

Back 148

Food and water supplies may be short during the dry season, and torpor enables animals to survive at a much lower metabolic rate.

Front 149

Concept 40.1: Physical laws and the environment constrain animal size and shape.

Back 149

Physical laws and animal form: The ability to perform certain actions, such as flying, depends on an animal's size and shape. Evolutionary convergence reflects different species' independent adaptation to a similar environmental challenge.

Front 150

Exchange with the environment: each cell of an animal must have access to an aqueous environment. Simple two-layered sacs and flat shapes maximize exposure to the surrounding medium. More complex body plans have highly folded internal surfaces specialized for exchanging materials.

Back 150

Concept 40.2: Animal form and function are correlated at all levels of organization.

Animals are composed of cells. Groups of cells with a common structure and function make up tissues. Different tissues make up organs, which together make up organ systems

Front 151

Tissue structure and function: epithelial tissue covers the outside of the body and lines internal organs and cavities. Connective tissues bind and support other tissues. Muscle tissue contracts, usually in response to nerve signals. Nervous tissue transmits nerve signals throughout the animal.

Back 151

Organ and organ systems: the body functions as a whole, greater than the sum of its parts, because of the activities of all tissues, organs, and organ systems are coordinated.

Front 152

Concept 40.3: Animals use the chemical energy in food to sustain form and function

Back 152

Bioenergetic: animals obtain chemical energy from food. Most energy is stored in ATP, which powers cellular work. An animal's metabolic rate is the total amount of energy it uses in a unit of time. Metabolic rates for birds and mammals, which maintain fairly constant body temperature using metabolic heat (the endothermic strategy), are generally higher than those of most fishes, non-bird reptiles, amphibians, and invertebrates that rely mostly on external sources of heat for maintaining body temperature (the ectothermic strategy)

Front 153

Influences on Metabolic rate: Metabolic rate per gram is inversely related to body size among similar animals. Activity increases metabolic rate above the BMR (endotherms) or SMR (ectotherms) of an animal. In general, endotherms can sustain high levels of activity longer than ectotherms can.

Back 153

Energy budgets: Animals use energy for basal (or standard) metabolism, activity, homeostasis (such as temperature regulation), growth, and reproduction

Front 154

Concept 40.4: Many animals regulate their internal environment within relatively narrow limits

Homeostasis describes an animal's internal steady state. It is a balance between external changes and the animal's internal control mechanisms that oppose the changes.

Back 154

Regulating and Conforming: Animals cope with environmental fluctuations by regulating certain internal variables while allowing others to conform to external changes

Front 155

Mechanisms of Homeostasis: The interstitial fluid surrounding an animal's cells is usually very different from the external environment. Homeostatic mechanisms moderate changes in the internal environment and usually involve negative feedback. These mechanisms enable regulated change.

Back 155

Concept 40.5: Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior

An animal maintains its internal temperature within a tolerable range by the process of thermoregulation

Front 156

Ectotherms and Endotherms: Most invertebrates, fishes, amphibians, and non-bird reptiles are ectotherms. Birds and mammals are endotherms. Endothermy is more energetically expensive than ectothermy. Maintaining a high body temperature enables an animal to maintain a high level of aerobic metabolism.

Back 156

Modes of Heat exchange: Conduction, convection, radiation, and evaporation account for heat gain or loss

Front 157

Balancing Heat Loss and Gain: Thermoregulation involves physiological and behavioral adjustments that balance heat gain and loss. Insulation, vasodilation, vasoconstriction, and countercurrent heat exchangers alter the rate of heat exchange. Panting, sweating, and bathing increase evaporation, cooling the body. Both ectotherms and endotherms adjust the rate of heat exchange with their surroundings by behavioral responses. Some animals can even adjust their rate of metabolic heat production.

Back 157

Feedback Mechanisms in Thermoregulation: Mammals regulate their body temperature by complex negative-feedback mechanisms that involve several organ systems, including the nervous, circulatory, and integumentary systems

Front 158

Adjustment in changing temperatures: Acclimatization enables ectotherms and endotherms to adjust to changing environmental temperatures over days or weeks. Acclimatization may involve cellular adjustments or, in the case of birds and mammals, adjustments of insulation and metabolic heat production

Back 158

Torpor and Energy Conservation: Torpor conserves energy during environmental extremes. Animals may enter torpor in winter (hibernation), summer (estivation), or during sleep periods (daily torpor). Torpor involves a decrease in metabolic rates and enables the animal to temporarily withstand unfavorable temperatures or lack of food and water.

Front 159

An adequate diet must satisfy three nutritional needs:

Back 159

Fuel (chemical energy) for all the cellular work of the body; the organic raw materials animals use in biosynthesis (carbon skeletons to make many of their own molecules); and essential mutrients, substances such as vitamins that the animal cannot make for itself from any raw material and therefore must obtain in food in prefabricated form.

Front 160

Concept 41.1:

Back 160

Homeostatic mechanisms manage an animal's energy budget

Front 161

Figure 41.2: Four main feeding mechanisms of animals

Back 161

Suspension feeders: sift small food particles from the water. Example, humpback whale uses comblinke plates called baleen attached to its upper jaw to strain small invertebrates and fish from enormous volumes of water. Among others, clams and oysters use their gills to trap tiny morsels. Cilia sweep the food particles in a film of mucus to the mouth

Substrate feeders: animals that live in or on their food source, eating their way through the food. This leaf miner catepillar, the larva of a moth, is eating through the soft mesophyll of an oak leaf, leaving a dark trail of feces in its wake.

Fluid feeders: suck nutrient-rich fluid from a living host. THis mosquito has pierced the skin of its human host with hollow, needlike mouthparts and is filling its digestive tract with a blood meal.

Bulk feeders: eat relatively large pieces of food. Their adaptations include such diverse utensils as tentacles, pincers, claws, poisonous fangs, jaws, and teeth that kill their prey or tear off pieces of meet or vegetation.

Front 162

When an animal takes in more calories than it needs to produce ATP, the excess can be used for

Back 162

Biosynthesis

Front 163

In humans, the liver and muscle cells store energy in the form of _________, a polymer made up of many glucose units.

Back 163

Glycogen

Front 164

_________ is a major fuel for cells, and its metabolism, regulated by hormone action, provides an important example of homeostasis.

Back 164

Glucose

Front 165

If the diet of a human or other animal is chronically deficient in calories, _________ results.

Back 165

Undernourishment

Front 166

Figure 41.3: Homeostatic regulation of cellular fuel.

After a meal is digested, glucose and other monomers are absorbed into the blood from the digestive tract. The human body regulates the use and storage of glucose, a major cellular level. Notice that these regulatory loops are examples of feedback control.

Back 166

1. When blood glucose level rises, a gland called the pancreas secretes insulin, a hormone, into the blood

2. Insulin enhances the transport of glucose into body cells and stimulates the liver and muscle cells to store glucose as glycogen. As a result, blood glucose level drops.

3. When blood glucose level drops, the pancreas secretes the hormone glucagon, which opposes the effect of insulin

4. Glucagon promotes the breakdown of glycogen in the liver and the release of glucose into the blood, increasing blood glucose level.

Front 167

Figure 41.4: Fat cells from the abdomen of a human

Back 167

Strands of connective tissue (yellow) hold the fat-storing adipose cells in place (colorized)

Front 168

Figure 41.5: A few of the appetite-regulating hormones.

Secreted by various organs and tissues, the hormones reach the brain via the bloodstream. The hormones act on a region of the brain that in turn controls the "satiety center" which generates the nervous impulses that make us feel either hungry or full. A green arrow indicates an appetite stimulate; red - suppressants

Green: Ghrelin
Red: Leptin, PYY, Insulin

Back 168

Produced by adipose (fat) tissue, leptin suppresses appetite as its level increases. When body fat decreases, leptin levels fall and appetite increases

The hormone PYY, secreted by the small intestine after meals, ats as an appetite suppressant that counters the appetite stimulant ghrelin

Secreted by the stomach wall, ghrelin is one of the signals that triggers feelings of hunger as mealtimes approach. In dieters who lose weight, ghrelin levels increase, which may be one reason why it's so hard to stay on a diet

A rise in blood sugar level after a meal stimulates the pancreas to secrete insulin. In addition to its other functions, insulin suppresses appetite by acting on the brain

Front 169

_________ is produced by adipose (fat) cells.

Back 169

Leptin

Front 170

Relatively few people have such a deficiency in leptin production. In fact, most obese humans have normally _________ levels of leptin, which, after all, is produced by adipose tissue. For some reason, the brain's satiety center does not respond to the high leptin levels in many people.

Back 170

High

Front 171

In what sense is a stable body weight a matter of caloric bookkeeping?

Back 171

Body weight is stable when caloric intake (food) is balanced by caloric expenditure (metabolic rate).

Front 172

Explain how it is possible for someone to become obese even if his or her intake of dietary far is relatively low compared to carbohydrate intake.

Back 172

Over the long term, the body converts excess calories to fat whether those calories are consumed as fat, carbohydrate, or protein.

Front 173

After reviewing Figure 41.5, explain how the hormones PYY and leptin complement each other in regulating body weight.

Back 173

Both hormones have appetite-suppressive effects on the brain's satiety center. During the course of a day, PYY, secreted by the small intestine, suppresses appetite after meals. Over the longer term, leptin, produced by adipose tissue, normally reduces appetites as fat storage increases

Front 174

Concept 41.2:

Back 174

An animal's diet must supply carbon skeletons and essential nutrients

Front 175

Besides fuel and carbon skeletons, an animal's diet must also supply ___________; these are materials that must be obtained in preassembled form because the animal's cells cannot make them from any raw material.

Back 175

Essential nutrients

Front 176

An animal whose diet is missing one or more essential nutrients is said to be __________.

Back 176

Malnourished

Front 177

There are four classes of essential nutrients:

Back 177

Amino acids, essential fatty acids, vitamins, and minerals

Front 178

Animals require 20 amino acids to make proteins, and most animal species can synthesize about half of these, as long as their diet includes organic nitrogen. The remaining ones, the ___________, must be obtained from food in prefabricated form.

Back 178

Essential amino acids

Front 179

A diet that provides insufficient amounts of one or more essential amino acids causes a form of malnutrition known as

Back 179

Protein deficiency

Front 180

Figure 41.8: Obtaining essential nutrients

Back 180

A caribous, an arctic herbivore, chews on discarded antlers from another animal. Antlers and skeletal bones contain calcium phosphate, and osteophagia ("bone eating") is common among herbivores living where soils and plant are deficient in phosphorus. Animals require phosphorus as a mineral nutrient to make ATP, nucleic acids, phospholipids, and bones

Front 181

The proteins in animal products are ___________, which means they provide all the essential amino acids in their proper proportions; most plant proteins are ___________, being deficient in one or more essential amino acids.

Back 181

Complete; incomplete

Front 182

The ___________, the ones they cannot make, are certain unsaturated fatty acids (fatty acids having double bond).

Back 182

Essential fatty acids

Front 183

Organic molecules required in the diet in amounts that are quite small compared with the relatively large required quantities of essential amino acids and fatty acids.

Back 183

Vitamins

Front 184

Vitamins grouped into two categories:

Back 184

Water-soluable - include B complex, which consists of several compounds that generally function as coenzymes in key metabolic process; excesses of water-soluable vitamins are excreted in uring, and moderate overdoses of these vitamins are probably harmless

Fat-soluable: A, D, E, K; excesses of fat-soluable vitamins are not excreted but are deposited in body fat, so overconsumption may result in accumulation of compounds to toxic level

Front 185

Required for the production of connective tissue

Back 185

Vit. C

Front 186

Incorporated into visual pigments of the eye

Back 186

Vit. A

Front 187

Aids in calcium absorption and bone formation

Back 187

Vit. D

Front 188

Seems to protect the phospholipids in membranes from oxidation

Back 188

Vit. E & C

Front 189

Required for blood clotting.

Back 189

Vit. K

Front 190

Water-Soluable Vitamins

Back 190

Vitamin B (thiamine)
Vitamin B2 (riboflavin)
Niacin
Vitamin B6 (pyridoxine)
Pantothenic acid
Folic acid (folacin)
Vitamin B12
Biotin
Vitamin C (ascorbinc acid)

Fat-Soluable Vitamins
Vitamin A (retinol)
Vitamin D
Vitamin E (tocopherol)
Vitamin K (phylloquinoe)

Front 191

Simple inorganic nutrients, usually required in small amounts - from less than 1 mg to about 2,500 mg per day

Back 191

Minerals

Front 192

Humans and other vertebrates need large quantities of ___________ and ___________ for the construction and maintenance of bone

Back 192

Calcium and phosphorus

Front 193

A component of the cytochromes that function in cellular respiration

Back 193

Iron

Front 194

Table 41.2: Mineral Requirements of Humans

Back 194

Calcium (Ca)
Phosphorus (P)
Sulfur (S)
Potassium (K)
Chlorine (K)
Sodium (Na)
Magnesium (Mg)
Iron (Fe)
Fluorine (F)
Zinc (Zn)
Copper (Cu)
Manganese (Mn)
Iodine (I)
Cobalt (Co)
Selenium (Se)
Chromium (Cr)
Molybdenum (Mo)

Front 195

Contrast undernutrition and malnutrition.

Back 195

Undernutrition is a deficiency of calories in the diet. In contrast, malnutrition results form a deficiency of one or more essential nutrients, even though total caloric intake may be adequate.

Front 196

Explain how a balanced vegetarian diet can provide all of the essential amino acids.

Back 196

A balanced vegetarian meal combines vegetables and fruits that complement one another, each providing certain essential amino acids that may be deficient in the other food items.

Front 197

Compare and contrast vitamins with minerals.

Back 197

Vitamins and minerals are essential nutrients required in relatively small daily amounts. Vitamins are organic nutrients, whereas minerals are inorganic nutrients.

Front 198

Concept 41.3:

Back 198

The main stages of food processing are ingestion, digestion, absorption, and elimination

Front 199

The act of eating, the first stage of food processing.

Back 199

Ingestion

Front 200

Animals cannot use these macromolecules direction for two reasons:

Back 200

Polymers are too large to pass through membranes and enter the cells of the animal.

Macromolecules that make up an animal are not identical to those of its food.

Front 201

The second stage of food processing, is the process of breaking down food into molecules small enough for the body to absorb

Back 201

Digestion

Front 202

__________ and __________ are split into simple sugars, fats are digested to glycerol and fatty acids, proteins are split into amino acids, and nucleic acids are cleaved into nucleotides

Back 202

Polysaccharides; disaccharides

Front 203

Digestion reverses, breaking down bonds with the addition of water; splitting process is called:

Back 203

Enzymatic hydrolysis

Front 204

Hydrolytic enzymes catalyze the digestion of each of the classes of macromolecules found in food. This chemical digestion is usually preceded by mechanical __________ of the food - by chewing. Breaking down food into smaller pieces increases the surface area exposed to digestive juices containing hydrolytic enzymes.

Back 204

Fragmentation

Front 205

Third stage, __________, the animal's cells take up (absorb) small molecules such as amino acids and simple sugars from the digestive compartment

Back 205

Absorption

Front 206

And finally, __________ occurs, as undigested material passes out of the digestive compartments

Back 206

Elimination

Front 207

Food vacuoles - cellular organelles in which hydrolytic enzymes break down food within digesting the cell's own cytoplasm - are the simplest digestive compartment. This digestion within a cell, called __________, begins after a cell engulfs food by phagocytosis or pinocytosis.

Back 207

Intracellular digestion

Front 208

The breakdown of food outside of the cells.

Back 208

Extracellular digestion

Front 209

Figure 41.12: The four stages of food processing

Back 209

Ingestion
Digestion
Absorption
Elimination

Food>
Mechanical digestion>
Pieces of food>
Chemical digestion (enzymatic hydrolysis)>
Small molecules>
Nutrient molecules enter body cells>
Undigested material

Front 210

Many animals with relatively simply body plans have a digestive sac with a single opening; this pouch functions in both digestion and distribution of nutrients throughout the body (hence the vascular part of the term)

Back 210

Gastrovascular cavity

Front 211

Hydras are carnivores that capture prey with specialized organelles called __________ and then use tentacles to stuff the food through their mouth into their gastrovascular cavity.

Back 211

Cnidae

Front 212

Specialized gland cells of this, the tissue layer that lines the cavity, then secrete digestive enzyme that break down the soft tissues of the prey into tiny pieces.

Back 212

Gastrodermis

Front 213

Other gastrodermal cells, called __________, engulf these food particles and most of the actual hydrolysis of macromolecules occurs intracellularly, as in sponges.

Back 213

Nutritive muscular cells

Front 214

Figure 41.13: Digestion in a hydra

Back 214

The outer epidermis of the hydra has protective and sensory functions, whereas the inner gastrodermis is specialized for digestion. Digestion begins in the gastrovascular cavity and is completed intracellularly after small food particles are engulfed by the gastrodermal cells.

Front 215

Figure 41.14: Variation in alimentary canals.

Back 215

a.) Earthworm. The digestive tract of an earthworm includes a muscular pharynx that sucks food in through the mouth. Food passes through the esophagus and is stored and moistened in the crop. The muscular gizzard, which contains small bits of sand and gravel, pulverizes the food. Further digestion and absorption occur in the intestine, which has a dorsal fold, the typhlosole, that increases the surface area for nutrient absorption

b.) Grasshopper. A grasshopper has several digestive chambers grouped into three main regions: a foregut, with an esophagus and crop; a midgut; and a hindgut. Food is moistened and stored in the crop, but most digestion occurs in the midgut. Gastric ceca, pouches extending from the midgut, absorb nutrients.

c.) Birds. Many birds have three separate chambers - the crop, stomach, and gizzard - where food is pulvarized and churned before passing into the intestine. A bird's crop and gizzard function very much like those of an earthworm. In most birds, chemical digestion and absorption of nutrients occur in the intestine.

Front 216

In contrast to cnidarians and flatworms, most animals - including menatodes, annelids, molluscs, arthropods, echinoderms, and chordates - have a digestive tube extending between two openings, a mouth and an anus. Such a tube is called:

Back 216

Complete digestive tract or an alimentary canal

Front 217

What is the main anatomical distinction between a gastrovascular cavity and an alimentary canal?

Back 217

A gastrovascular cavity is a digestive sac with a single opening that functions in both ingestion and elimination; an alimentary canal is a digestive tube with a separate mouth and anus on opposite ends.

Front 218

Why are nutrients from a recently ingested meal not really "inside" your body prior to the absorption stage of food processing?

Back 218

As long as nutrients are within the cavity of the alimentary canal, they are in a compartment that is continuous with the outside environment via the mouth and anus and have not yet entered the body by crossing the membrane

Front 219

Concept 41.4:

Back 219

Each organ of the mammalian digestive system has specialized food-processing functions

Front 220

Rhythmic waves of contraction by smooth muscles in the wall of the canal, pushes the food along the tract.

Back 220

Peristalsis

Front 221

Ringlike valves, which close off the tube like drawstrings, regulating the passage of material between chambers of the canal.

Back 221

Spincters

Front 222

The accesory glands of the mammalian digestive system are three pairs of salivary glands:

Back 222

The pancreas, the liver, and the gallbladder - which stores a digestive juice

Front 223

Figure 41.15: The Human Digestive System

Back 223

After food is chewed and swallowed, it take only 5-10 seconds for it to pass down the esophagus and into the stomach, where it spends 2-6 hours being partially digested. Final digestion and nutrient absorption occur in the small intestine over a period of 5-6 hours. In 12-24 hours, any undigested material passes through the large intestine, and feces are expelled through the anus

Front 224

The presence of food in the __________ triggers a nervous reflect that cause the salivary glands to deliver saliva through ducts to the oral cavity

Back 224

Oral cavity

Front 225

Saliva contains a slippery __________ (carbohydrate-protein complex) called __________, which protects the lining of the mouth from abrasion and lubricates food for easier swallowing.

Back 225

Glycoprotein; mucin

Front 226

Chemical digestion of carbs, a main source of chemical energy, begins in the oral cavity. Saliva contains __________, an enzyme that hydrolyzes starch and glycogen.

Back 226

Salivary amylase

Front 227

The main __________ of this enzyme's action are smaller polysaccharides and the disaccharide maltose.

Back 227

Products

Front 228

The tongue tastes food, manipulates it during chewing and helps shape the food into a ball called:

Back 228

Bolus

Front 229

A junction that opens to both the esophagus and the windpipe (trachea)

Back 229

Pharynx

Front 230

When we swallow, the top of the windpipe moves up so that its opening, the glottis, is blocked by a cartilaginous flap, the __________

Back 230

Epiglottis

Front 231

Conducts food from the pharynx down to the stomach by peristalsis

Back 231

Esophagus

Front 232

Figure 41.16: From mouth to stomach: the swallowing reflex and esophageal peristalsis.

Back 232

1.) When a person is not swallowing, the esophageal sphincter muscle is contracted, the epiglottis is up, and the glottis is open, allowing air to flow through the trachea to the lungs

2.) The swallowing reflex is triggered when a bolus of food reaches the pharynx

3.) The larynx, the upper part of the respiratory tract, moves upward and tips the epiglottis over the glottis, preventing food from entering the trachea

4.) The esophageal sphincter relaxes, allowing the bolus to enter the esophagus

5.) After the food has entered the esophagus, the larynx moves downward and opens the breathing passage

6.) Waves of muscular contraction (peristalsis) moves the bolus down the esophagus to the stomach

Front 233

Stores food and performs preliminary steps of digestion

Back 233

Stomach

Front 234

Stomach secretes a digestive fluid __________ and mixes this secretion with the food by churning action of the smooth muscle in the stomach wall.

Back 234

Gastric juice

Front 235

__________ is secreted by the epithelium lining numerous deep pits in the stomach wall.

Back 235

Gastric juice

Front 236

Also present in gastric juice is __________, an enzyme that begins the hydrolysis of proteins.

Back 236

Pepsin

Front 237

Figure 41.17: The stomach and its secretions

Back 237

The micrograph shows a gastric pit on the interior surface of the stomach, through which digestive juices are secreted

Interior surface of stomach: The interior surface of the stom. wall is highly folded and dotted with pits leading into tublar gastric glands

Gastric gland: The gastric glands have three types of cells that secrete different components of the gastric juice: mucus cells, chief cells, and parietal cells

Mucus cells: secret mucus, which lubricates and protects the cells lining the stomach

Chief cells: secrete pepsinogen, an inactive form of the digestive enzyme pepsin

Parietal cells: secrete hydrocloric acid (HCL)

1.) Pepsinogen and HCL are secreted into the lumen of the stomach

2.) HCL converts pepsinogen to pepsin

3.) Pepsin then activates more pepsinogen, starting a chain reaction. Pepsin begins the chemical digestion of proteins.

Front 238

As a result of mixing and enzyme action, what begins in the stomach as a recently swallowed meal becomes a nutrient-rich broth known as __________

Back 238

Acid chyme

Front 239

At the opening from the stomach to the small intestine is the __________, which helps regulate the passage of chyme into the intestine, one squirt at a time.

Back 239

Pyloric sphincter

Front 240

With a length of more than 6m in humans, the __________ is the longest section of the alimentary canal.

Back 240

Small intestine

Front 241

The first 25cm of the small intestine is __________, here, that acid chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and gland cells of the intestinal wall itself.

Back 241

Duodenum

Front 242

A mixture of substances that is stored in the gallbladder until needed. Contains no digestive enzymes, but it does contain bile salts, which act as detergents (emulsifiers) that aid in the digestion and absorption of fats - produced in liver.

Back 242

Bile

Front 243

Figure 41.19: The duodenum

Back 243

Hydrolytic enzymes from accessory glands mix with acid chyme in the duodenum, continuing the digestion process. Note that bile is produced in the liver but stored in g. bladder, which releases it into the duo. as needed.

Front 244

Figure 41.20: Protease activation

Back 244

The pancreas secretes inactive proteases into the duo. An enzyme calle denteropeptidase, which is bound to the intestinal epithelium, converts trysinogen to trypsin. Trypsin then activates other proteases.

Front 245

Figure 41.21: Flowchart of enzymatic digestion in the human digestion

Back 245

Pg. 859

Front 246

Large circular folds in the lining of the small int. bear fingerlike projections called __________, and each epithelial cell of a villus has many microscopic appendages called microvilli that are exposed to the intestinal lumen.

Back 246

Villi

Front 247

Penetrating the core of each villus is a net of microscopic blood vessels (capillaries) and a small vessel of the lymphatic system called:

Back 247

Lacteal

Front 248

Figure 41.22: Hormonal control of digestion

Many animals go for long intervals between meals and do not need their digestive systems to run continously. Hormones released by the stom. and duo. help ensure that digestive secretions are present only when needed.

Back 248

Amino acids or fatty acids in the duo. trigger the release of cholecystokinin (CCK), which stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder.

Enterogastrone secreted by the duo. inhibits peristalsis and acid secretion by the stomach, thereby slowing digestion when acid chyme rich in fats enters the duo.

Gastrin from the stomach recirculates via the bloodstream back to the stomach, where it stimulates the production of gastric juices.

Secreted by the duo., secretin stimulates the pancreas to release sodium bicarbonate, which neutralizes acid chyme from the stomach

Front 249

Figure 41.24: Digestion and absorption of fats. Hydrolysis of fats is a digestive challenge b/c fat molecules are insoluable in water. However, bile salts from the gallbladder secreted into the duo. coat tiny fat droplets and keep them from coalescing, a process called emulsification. Because the droplets are small, a large urface area of fat is exposed to lipase. Once the fat molecules have been hydrolyzed, they form micelles, which enable the fatty substances to diffuse into the epithelial lining of the small intestine. From the epithelial cells, they can be absorbed into the circulatory system.

Back 249

1.) Large fat globules are emulsified by bile salts in the duo.

2.) Digestion of fat by the pancreatic enzyme lipase yields free fatty acids and monoglycerides , which then form miceels

3.) Fatty acids and monoglycerides leave micelles and enter epithelial cells by diffusion. There, they are recombined into fats and formed into chylomicrons

4.) Chylomicros containing fatty substances leave epithelial cells by exocytosis and enter lacteals, where they are carried away from the intestine by lymph

Front 250

The fats are then mixed with cholesterol and coated with proteins, forming small globules called __________, most of which are transported out of the epithelial cells and into lacteals.

Back 250

Chylomicrons

Front 251

__________, containing chylomicrons, eventually drains from the lymphatic system into large veins that return blood to the heart

Back 251

Lymph

Front 252

A blood vessel that leads directly to the liver

Back 252

Hepatic portal vein

Front 253

Colon, is connected to the small int. at a T-shaped junction, where a sphincter (a muscular valve) controls the movement of material.

Back 253

Large intestine

Front 254

One arm of the T is a pouch called the:

Back 254

Cecum

Front 255

The human cecum has a fingerlike extension, the __________, which is dispensible.

Back 255

Appendix

Front 256

A major function of the colon is the:

Back 256

Recover water that has entered the alimentary canal as the solvent of the various digestive juices

Front 257

The wastes of the digestive tracts, __________, become more solid as they are moved along the colon by peristalsis.

Back 257

Feces

Front 258

The terminal portion of the colon is called the __________, where feces are stored until they can be eliminated

Back 258

Rectum

Front 259

In the weightless environment of space, how does food swallowed by an astronaut reach the stomach?

Back 259

Perstalsis can squeeze food through the esophagus even without the help of gravity.

Front 260

Describe two key digestive functions of the hydrochloric acid in gastric juice.

Back 260

The acid breaks down the tissues in plant and animal materials by its harsh, nonenzymatic, chemical attack. The acid also activates the protein-digesting enzyme pepsin and destroys any bacteria that may have been ingested with food

Front 261

What materials are mixed within the duo. during digestion of a meal?

Back 261

The partially digested meal entering form the stomach as acid chyme + pancreatic juice containing hydrolytic enzymes + intestinal juice with enzymes + bile, which includes bile salts that aid in digstion by emulsifying fats

Front 262

How is the structure of the brush border (epithelium) of the small intestine adapted to its function of nutrient absorption?

Back 262

The villi and microvilli of the intestinal epithelium provide an enormous surface area for absorption, the transport of nutrients form the lumen of the small int. into blood capillaries and lacteals

Front 263

Explain why treatment of a chronic infection with antibiotics for an extended period of time may cause vitamin K deficiency.

Back 263

Long-term use of antibiotics can kill colon bacteria that augment nutrition by producing vitamin K

Front 264

After reviewing Figure 41.22, explain how the pancreas times its secretion of digestive juice to mix with a partially digested meal in the duodenum.

Back 264

As it receives acid chyme from the stomach, the duo. secretes the hormong cholecystokinin (CCK), which reaches the pancreas via the bloodstream and stimulats release of pancreatic juice

Front 265

Concept 41.5:

Back 265

Evolutionary adaptations of vertebrate digestive systems are often associated with diet

Front 266

__________, an animal's assortment of teeth.

Back 266

Dentition

Front 267

Figure 41.26: Dentition and diet

Back 267

a.) Carnivores generally have pointed incisors and canines that can be used to kill prey and rip or cut away pieces of flesh. The jagged premolars and molars crush and shred food.

b.) In contrast, herbivorous mammals usually have teeth with broad, ridged structures that grind tough plant material. The incisors and canines are generally modified for biting off pieces of vegetation. In some herbivoros, canines are absent

c.) Humans, being omnivorous adapted for eating both vegetation and meat, have relatively unspecialized dentition.

Front 268

Large, expandable __________ are common in carnivores, which may go for a long time between meals and therefore must eat as much as they can when they do catch prey.

Back 268

Stomachs

Front 269

__________ is more difficult to digest than meat b/c it contains cell walls.

Back 269

Vegetation

Front 270

Figure 41.27: The digestive tracts of a carnivore and herbivore

Back 270

Herb's int's are much longer, as adaptation that enhances processing of fibrous, protein-poor eucalyptus leaves from which it obtains virtually all its food and water. Extensive chewing chops the leaves into very small pieces, increasing exposure of the food to digestive jucies. The herb's cecum functions as a fermentation chamber where symbiotic bacteria convert the shredded leaves into a more nutritious diet

Front 271

Figure 41.28: Ruminant digestion -- the stom. of a ruminant has four chambers. B/c of the microbial action in the chambers, the diet from which a ruminant actually absorbs its nutrients is much richer than the grass the animal originally ate. In fact, a ruminant eating grass or hay obtains many of its nutrients by digesting the symbiotic microorganisms, which reproduce rapidly enough in the rumen to maintain a stable population.

Back 271

1.) Rumen: when the cow first chews and swallows a mouthful of grass, boluses enter the rumen

2.) Reticulum: some boluses also enter the reticulum. in both the rumen and the reticulum, symbiotic prokaryotes and protists (mainly ciliates) go to work on the cellulose-rich meal. as by-products of their metabolism, the microorganisms secrete fatty acids. the cow periodically regurgitates and rechews the cud, which further breaks down the fibers, making them more accessible to further microbial action.

3.) Omasum: the cow then reswallows the cud, which moves to the omasum, where water is removed

4.) Abomasum: the cud, containing great numbers of microorganisms, finally passes to the abomasum for digestion by the cow's own enzymes

Front 272

Explain how human dentition is adapted for an omnivorous diet.

Back 272

The sharp incisors are adapted for cutting pieces of meat and plants. The broad, ridged surfaces of molars are adapted for grinding tough foods.

Front 273

Compared with an adult frog, a tadpole (frog larva) has a much longer intestine relative to its body size. What does this suggest about the diets of these two stages in a frog's life history?

Back 273

The tadpole is herbivorous (eats mostly algae), while the adult frog is carnivorous (eats insects, etc.)

Front 274

"Chewing its cud" is a common expression about cattle. What is the cud, and what role does it play in bovine nutrition.

Back 274

The cud is a regurgitated brew of material from the rumen - once-chewed vegetation with fatty acids and other metabolic byproducts of the rumen bacteria. After a second chewing, which increases the surface area of the plant material, the cow swallows the cud, and microbial action in the stomach chambers continues to convert cellulose to a diversity of nutrients

Front 275

Chapter 41 Review: Key concepts - an animal's diet must supply chemical energy, organic raw materials, and essential nutrients. Herbivores mainly eat plants, carnivores mainly eat other animals, and omnivores eat both plant and animal matter. Many aquatic animals are suspension feeders, sifting small particles from the water. Substrate feeders tunnel through their food, eating as they go. Fluid feeders suck nutrient-rich fluids from a living host. Most animals are bulk feeders, eating large pieces of food.

Back 275

Concept 41.1: Homeostatic mechanisms manage an animal's energy budget

Front 276

Glucose regulation as an example of homeostasis: Vertebrates store excess calories as glycogen in the liver and muscles and as fat. These energy stores can be tapped when an animal expends more calories than it consumes. Blood glucose level is maintained within a relatively narrow range by a negative feedback mechanism

Back 276

Caloric imbalance: undernourished animals have diets deficient in calories. Overnourished (obese) animals consume more calories than they need. Obesity is a serious health problem worldwide and especially in the US, where lack of exercise and fattening foods make an unhealthy combination. Obesity is also strongly influenced by genes. The problem of maintaining a healthy weight partly stems from our evolutionary past, when fat hoarding may have been important for survival.

Front 277

Concept 41.2: An animal's diet must supply carbon skeletons and essential nutrients

Carbon skeletons are required in biosynthesis. Essential nutrients must be supplied in preassembled form. Malnourished animals are missing one or more essential nutrients in their diet.

Back 277

Essential Amino Acids: Animals require 20 amino acids and can synthesize about half of them from the other molecules they obtain from their diet. Essential amino acids are those an animal cannot make. An animal whose diet is lacking one or more essential amino acids will become malnourished and suffer protein deficiency

Front 278

Essential Fatty Acids: Essential fatty acids, which an animal cannot make, are unsaturated, meaning that they have double bonds. Deficiencies in essential fatty acids are rare.

Back 278

Vitamins: Vitamins are organic molecules required in small amounts - water/fat-soluable

Front 279

Minerals: Minerals are inorganic nutrients usually required in small amounts

Back 279

Concept 41.3: The main stages of food processing are ingestion, digestion, absorption, and elimination

Food processing in animals involves ingestion (the act of eating), digestion (enzymatic breakdown of the macromolecules of food into their monomers), absorption (the uptake of nutrients by body cells), and elimination (the passage of undigested materials out of the body in feces)

Front 280

Digestive Compartments: in intracellular digestion, food particles are engulfed by endocytosis and digested within food vacuoles. Most animals use extracellular digestion, with enzymatic hydrolysis occurring outside cells in a gastrovascular cavity or alimentary canal

Back 280

Concept 41.4: Each organ of the mammalian digestive system has specialized food-processing functions

The mammalian digestive system is composed of the alimentary canal and accessory glands that secrete digestive juices into the canal

Front 281

The Oral Cavity, Pharynx, and Esophagus: Food is lubricated and digestion begins in the oral cavity, where teeth chew food into smaller particles that are exposed to salivary amylase, initiating the breakdown of glucose polymers. The pharynx is the intersection leading to the trachea and esophagus. The esophagus conducts food from the pharynx to the stomach by involuntary peristaltic waves.

Back 281

The stomach: The stomach stores food and secretes gastric juice, which converts a meal to acid chyme. Gastric juice includes hydrochloric acid and the enzyme pepsin

Front 282

The small intestine: the small intestine is the major organ of digestion and absorption. Acid chyme from the stomach mixes in the duo. with intestinal juice, bile, and pancreatic juice. Diverse enzymes complete the hydrolysis of food molecules to monomers, which are absorbed into the blood and lymph across the lining of the small intestine. Hormones help regulate digestive juice secretions.

Back 282

The large intestine: the large intestine (colon) aids the small intestine in reabsorbing water and houses bacteria, some of which synthesize vitamins. Feces pass through the rectum and out the anus.

Front 283

Concept 41.5: Evolutionary adaptations of vertebrate digestive systems are often associated with diet

Back 283

Some dental adaptations: a mammal's dentition is generally correlated with its diet. In particular, mammals have specialized dentition that best enables them to ingest their usual diet.

Front 284

Stomach and Intestinal adaptations: Herbivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation.

Back 284

Symbiotic adaptations: many herbivorous animals have fermentation chambers where symbiotic microorganisms digest cellulose

Front 285

Chapter 42:

Back 285

Circulation and Gas exchange

Front 286

Open and closed circulatory systems have three basic components:

Back 286

A circulatory fluid (blood), a set of tubes (blood vessels) through which the blood moves through the body, and a muscular pump 9the heart).

Front 287

The heart powers circulation by using metabolic energy to elevate the hydrostatic pressure of the blood which then flows down a pressure gradient through its circuit and back to the heart. This ________ is the motive force for fluid movement in the circulatory system

Back 287

Blood pressure

Front 288

In an open circ. sys, there is not distinction between blood and interstitial fluid, and this general body fluid is more correctly termed

Back 288

Hemolymph

Front 289

One or more hearts pump the hemolymph into a interconnected system of __________, which are spaces surrounding the organs.

Back 289

Sinuses

Front 290

In a ___________, blood is confined to vessels and is distinct from the interstitial fluid

Back 290

Close circulatory system

Front 291

Materials are exchanged by ________ between the blood and the interstitial fluid bathing the cells

Back 291

Diffusion

Front 292

_________ systems require less energy to build and maintain

Back 292

Open

Front 293

_________ systems, with their higher blood pressure, are more effective at transporting circulatory fluids to meet he high metabolic demands of the tissues and cells of the larger and more active animals.

Back 293

Closed

Front 294

Humans and other vertebrates have a closed circulatory sys, often called:

Back 294

Cardiovascular system

Front 295

The vertebrate heart as one or two _______, the chambers that receive blood returning to the heart; and one or two ________, the chambers that pump blood out of the heart

Back 295

Atria; ventricles

Front 296

Three main kinds of blood vessels

Back 296

Arteries, veins, and capillaries

Front 297

Networks of these vessels

Back 297

Capillary beds

Front 298

At their downstream end, capillaries converge into _______, which converges into veins.

Back 298

Venules

Front 299

All _______ carry blood from the heart toward the capillaries

Back 299

arteries

Front 300

All _____ return blood to the heart from the capillaries

Back 300

Veins

Front 301

This vein carries blood from capillary beds in the digestive system to capillary beds in the liver

Back 301

Hepatic portal

Front 302

Figure 42.3: Open and closed circulatory systems

Back 302

a.) An open circulatory system: an open circulatory system, such as that of a grasshopper, blood and interstitial fluid are the same, and this fluid is called hemolymph. The heart pumps hemolymph through vessels into sinuses, where materials are exchanged between the hemolymph and cells. Hemoplymph returns to the heart through ostia, which are equipped with valves that close when the heart contracts

b.) A closed circulatory system: closed sys circulate blood entirely within vessels, distinct from the interstitial fluid. Chemical exchange occurs between the blood and the interstitial fluid, and between the int. fluid and body cells. IN an earthworm, three major vessels branch into smaller vessels that supply blood to the various organs. THe dorsal vessel functions a sthe main heart, pumping blood forward by peristalsis. Near the worm's anterior end, five parts of vessels loop around the digestive tract and function as auxiliary hearts, propelling blood ventrally

Front 303

Fishes - circ. sys

Back 303

Has two main chambers, one ventricle and one atrium. Blood pumped from the ventricle travels first to the gills (gill circ.) where it picks up oxygen and disposes of carbon dioxide across capillary walls. The gill capi. converge into a vessel that carries oxygen-rich blood to capillary beds throughout all other parts of the body (the sys circ.). Blood then returns in veins to the atrium of the heart. Notice that in a fish, blood must pass through two capillary beds during each circuit.

Front 304

Amphibibians - circ. sys

Back 304

Have three-chambered heart, two atria and one ventricle. Ventricle pumps blood into a forked artery that split the ventricles output into the pulmocutaneous circuit and the sys. circuit. The pulm. circuit leads to capi. in the gas exchange organs (lungs and skin of frogs) where blood picks up O2 and release CO2 before returning to heart's left atrium. Most of the returning oxygen-rich blood is pumped into the systematic circuit, which supplies all organs and then returns oxygen-poor blood to the right atrium via the veins. In the ventricle, there is some mixing of oxygen-rich and and poor blood. However, a ridge within the vent. diverts most of the oxy-rich blood from the left atrium into the sys. circuit and most of the oxy-poor blood from the right atrium into the pulm. circuit.

Organization, double circulation, provides a vigorous flow of blood to the brain, muscule, and other organs b/c the blood is pumped a second time after it loses pressure in the capillary beds of the lungs or skin

Front 305

Figure 42.4: Vertebrate Circulatory System

Back 305

Pg. 870-871

Front 306

What fundamental physical constraint necessitates a circulatory system in large organisms?

Back 306

The inability of diffusion to deliver nutrients and remove wastes at high enough rates to sustain a large organism

Front 307

What is one advantage of a closed circulatory system? What is a disadvantage?

Back 307

Advantage: high rate of delivery of nutrients and removal of wastes. Disadvantage: requires more energy to build, operate, and maintain

Front 308

What are two physiological advantages of separate repiratory (pulmocutaneous or pulmonary) and systematic circuits over a single circuit as seen in fishes, which combines gill and systemic circulation?

Back 308

Two main adv. of separate respi. and syst. circuits are higher blood press. in the syst. circuit and a higher rate of blood circulation

Front 309

Mammalian Circulation: The pathway - pg. 872

Back 309

1.) The right ventricle pumps blood to the lungs via
2.) the pulmonary arteries. As the blood flows through
3.) the capillary beds in the left and right lungs, it loads O2 and unloads CO2. Oxygen-rich blood returns from the lungs via the pulmonary veins to
4.) the left atrium of the heart. Next, the oxygen-rich blood flows into
5.) the left ventricle as the ventricle opens and the atrium contracts. The left ventricle pumps the oxygen-rich blood out to body tissues through the systemic circuit. Blood leaves the left ventricle via
6.) the aorta, which conveys blood to arteries leading throughout the body. The first branches from the aorta are the coronary arteries (not shown), which supply blood to the heart muscle itself. Then come branches leading to capillary beds
7.) in the head and arms (forelimbs). The aorta continues in a posterior direciton, supplying oxygen-rich blood to arteries leading to
8.) arterioles and capillary beds in the abdominal organs and legs. Within the capillaries, O2 and CO2 diffuse along their concentration gradients, with O2 moving form the blood to the tissues and CO2 produced by cellular respiration diffusing into the bloodstream. Capillaries rejoin, forming venules, which convey blood to veins. Oxygen-poor blood from the head, neck and forelimbs is channeled into a large vein called
9.) the anterior vena cava. Another large vein called
10.) the posterior vena cava drains blood from the trunk and hind limbs. The two vena cavae empty their blood into
11.) the right atrium, from which the oxygen poor blood flows into the right ventricle

Front 310

Refers to one complete sequence of pumping and filling.

Back 310

Cardiac cycle

Front 311

The contraction phase of the cycle

Back 311

Systole

Front 312

The relaxation phase

Back 312

Diastole

Front 313

The volume of blood per minute that the left ventricle pumps into the sys. circuit

Back 313

Cardiac output

Front 314

Cardiac output depends on two factors: the rate of contraction, or ______, and stroke volume, the amount of blood pumped by the left ventricle in each contraction

Back 314

Heart rate