Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

185 Cards in this Set

  • Front
  • Back
What is the advantage of a closed circulatory system over an open one?
It can move blood more efficiently.
Which heart chamber supplies oxygenated blood to the heart muscle
left ventricle
A three-chambered heart
) has two atria and one ventricle
Which heart chamber is the most muscular?
the left ventricle
In humans, the tricuspid valve is found
between the right atrium and the right ventricle
Why is it important that the atrioventricular (AV) node produce a delay between the contraction of the atria and the contraction of the ventricles?
It allows the ventricles to fill to capacity
Ventricles force blood directly into
The cardiac cycle is
the alternating relaxation and contraction of heart chambers.
Which blood constituent makes up more of the volume of blood?
) plasma
Erythrocytes are produced in the
) bone marrow.
) protect body from microbes.
Which of the following does NOT play a role in blood clotting?
All hormones are
delivered to their target tissue by the bloodstream
) You go to the doctor and are given a shot of hormone as treatment for your condition. The doctor tells you that the shot won't start to work for about 18-24 hours. Based on the amount of time that it takes for the hormone to work, which of the following categories is the hormone most likely to belong to?
) steroid hormones
Hormones that react with protein receptors on the surface of the target cell are
peptide and amino acid
Proteins which identify a cell as a target cell for a hormone are called
Water-soluble hormones bind to molecules in the ________ of the target cell
plasma membrane
Most of the steroid hormones are synthesized from
) cholesterol.
Which of the following is an example of a positive feedback control system?
During birth, the baby's head presses against the cervix and stretches it; stretch of the cervix stimulates the release of oxytocin; oxytocin causes contractions of muscles in the uterus; this pushes the baby against the cervix harder, increasing the stretch of the cervix.
The ________ pituitary releases hormones produced from cells in the hypothalamus.
Which of the following secretes releasing and inhibiting hormones?
The cells that control the secretion of all of the hormones produced by the pituitary are in the
) Which is NOT an effect of thyroxine
) increasing body temperature
B) stimulating metabolic rate
C) stimulating growth of the nervous system
D) triggering the metamorphosis of tadpoles
Which hormone decreases blood glucose concentrations
) insulin
Glucagon increases blood glucose by activating an enzyme which breaks down glycogen which has been stored primarily in the
) liver.
Which of the following stimulates the storage of glucose
) insulin
Which portion of the neuron typically receives information
Which portion of the neuron contains receptor proteins
Which of the following is an important similarity between the endocrine system and the nervous system
The transmitters from both cause a change in target cells throughout the body.
B) Both involve both electrical and chemical aspects.
C) The speed of response is the same.
D) Both transmit their compounds into the bloodstream.
Which of the following represents the direction a nerve impulse travels within a single neuron?
dendrite  cell body  axon  synaptic terminal
An excitatory postsynaptic potential will stimulate
) the opening of sodium channels.
The negative resting potential of a neuron is due to
the action of the sodium-potassium pump.
B) the trapping of large negative organic molecules inside the cell.
C) diffusion of potassium ions out of the cell.
) Neurons (and most other animal cells) have a negative inside potential because
) they leak potassium through open channels in the plasma membrane.
) In neurons, ________ ions are at higher concentration inside the cell and ________ ions are at higher concentration in the extracellular fluid.
K; Na
In a nerve cell at its resting potential ________ are closed
sodium channels
The resting potential of neurons is between ________ millivolts.
-40 and -90
) The sodium-potassium pump pumps
potassium in and sodium out of the cell
) Axons
carry an action potential in the direction of a synapse.
The intensity of the stimulus is indicated by the ________ of action potentials
) frequency
Which of the following most accurately describes why your brain can distinguish lights from sounds.
Because the brain monitors which action potentials come from the eye and which action potentials come from the ear.
The kinds of peripheral neurons that are responsible for involuntary responses to extreme danger or stress are the
) sympathetic.
Which of the following are found in the human central nervous system?
) spinal cord
B) forebrain (cerebrum)
C) hypothalamus
D) all of these
In a goldfish, information from the eyes is processed by the
) midbrain.
Most brain cells are ________ neurons
) association
What type of neuron will activate the biceps muscle in your arm?
) motor
The cell bodies of motor neurons are located
) in the gray matter of the spinal cord.
) The autonomic nervous system controls
contraction of involuntary muscles
If an animal is especially coordinated in its movements, it will probably have a larger than normal
) cerebellum.
The part of the brain that controls involuntary actions, such as breathing is the
The structure responsible for transferring short-term memories into long-term memories is the
) hippocampus.
Which of the following is a mechanoreceptor
) hair cell
) The fovea of the human eye is
the part of the retina that produces the sharpest image.
The hormones produced by the pituitary that are primarily responsible for the onset of puberty are
luteinizing hormone (LH) and follicle stimulating hormone (FSH).
What is the function of Sertoli Cells?
regulate sperm production
) nourish the developing sperm
What is the function of an acrosome
) It contains enzymes used to dissolve the protective layers around the egg.
Which hormone stimulates the production of testosterone
) luteinizing hormone
Sperm are stored in the
The epididymis connects
testis and vas deferens.
In humans, oogenesis is halted in the ________ until pituitary hormones stimulate a continuation of division.
) first meiotic division
) The egg that is released from the ovary during ovulation is known as a(n)
secondary oocyte.
In humans, fertilization normally occurs in the
) oviduct.
Ovulation occurs due to a surge in
LH concentrations.
) In which structure would a corpus luteum be located?
Gonadotropin releasing hormone (GnRH)
stimulates the release of FSH and LH.
Which of the following reproductive events occurs only in females?
) Gamete production results in both gamete and polar body formation
Erection of the penis occurs by
increased blood flow into it.
Vasectomy and tubal ligation result in
an interruption of the path taken by egg or sperm
) If each of the vas deferens of a male human were cut, his semen would not contain
A fertilized oyster egg develops into a free-swimming larval stage called a veliger. The veliger later settles and grows a shell. This is an example of
) indirect development.
Which of the following statements regarding extraembryonic membranes is TRUE?
The amnion encloses the embryo in a watery environment
Which extra-embryonic membrane lies immediately beneath the shell of a reptile embryo?
) Which is the BEST definition of cleavage (as applied to embryos!)?
) early rapid division of the zygote
At the blastula stage, the embryo consists of
a hollow ball of cells.
If an animal is missing its outer layer of skin upon birth, which of the following might cause it?
) loss of ectoderm
The nervous system forms from the
The result of gastrulation is
) a three-layered embryo.
Humans are not born with webs between their fingers due to the process of
) programmed cell death.
If a cell divides by mitosis so that one cell eventually becomes part of the brain and the other cell becomes part of a salivary gland, the cells have
Which of the following is TRUE of stem cells?
They can become other, specialized kinds of cells.
) Induction refers to
) substances from one embryonic cell influencing the development of other cells.
A human embryo is known as a fetus after
) 8 weeks.
) At what stage does a human embryo implant in the uterus?
) blastocyst
Which portion of the blastula becomes the embryonic placenta
Which of the following cannot cross the placenta?
) alcohol
B) cocaine
C) AIDS virus
D) nicotine
E) All of these cross the placenta.
Most fetuses can first survive outside the womb after a minimum of
seven months.
Vena Cava
R. Atrium
R. Ratrioventricular Valve
R. Ventrical
R. Semiluar Vavle
Pulmonary Artery
Pulmoniary Veins
L Atrium
L Ratroventricular Valve
L. Ventrical
L. Semilunar Valve
maintaines eternal balances by telling the body what to do. It maintains through the nervous system and the endocrine system.
Endocrine System
helps regulate mood, growth and development, tissue function, metabolism, as well as sexual function and reproductive processes.
Extracellular Fluid (Outside of Cell)
the volume of body fluid excluding that in cells. ECF includes the fluid in blood vessels (plasma) and fluid between cells (interstitial fluid).
Interstitial fluid
Fatty fluid between cells, too much fluid will cause swelling.
Used to Treat Clotting

Major portion of blood.

contains albumin
A protein manufactured by the liver
Mechanisms of Homeostasis
Sensory receptors
Detect stimulus (ie., nerve ending)

Selects response (such as the brain)

Carry out response (a muscle or gland)

Note: If a neg feedback the system cancels or conteracts the effect.
Negative Feedback
NOte: You have more neg feedback than pos.

Analogy for your body is like a furnance thermostat. (Maintain the body temp)

Helps maintain normal body ranges.
small structure at the base of the brain that regulates many body functions, including appetite and body temperature.
Positive Feedback
Intensifies the changes. (i.e, childbirth, sexual intercourse)
Cells construct tissues and there are only 4 types of tissues
Epithelia - Membranes that cover the outside of a body and line its cavities (2 types, external is a barrier, no water can get into your body. Internal allows for movement of gases) continual replacement., they form glands (Exocrine glands like sweat glands and Endocrine glands those that produce hormones. Very thin, one cell thick.

Connective - provides strength and connectivity. Loose - holds tissue to make organs., fibrous - tendons, ligaments, specialized, cartlage, bone.

Muscle - specialized for contraction., specalized cells are called muscle fibers, 3 types, skeletal, cardiac, smooth.

Nervous - cells called neurons, transmits info
Tissues make organs (2 tissues that function together)
skin, heart, kidney
Organs make organ systems
2 or more organs that work to perform a common function. (ie., digestive system, stomach, intestines, liver, pancreas)
Organ system helps us
respiring (lungs)

circulating blood (heart, arteries)




Epithelial Tissues
Cuboidal: Cube-shaped with nuclei centrally located
Found in thyroid, pancreas, salivary glands & line kidneys
Function: secretion & absorption

A. Squamous (simple): (lung) membranes, blood vessels
Function: diffusion

Squamous (stratified): on the outer surface of skin
Function: protection (especially from dessication

Columnar: long, column-like cells with nuclei usually located at the base of cells
Function: absorption (found in the intestines)
Specialized Connective Tissue
Adipose Tissue: loose, irregular arrangement of fibers. Fat cells, stores energy and cushions delicate organs
Cartilage: extensive, rigid extracellular matrix. Chondrocytes are cartilage producing cells.
Function: flexible support structure, shock absorption
Bone: intercellular matrix contains numerous fibers & water, and inorganic salts.
Function: support structure & protection for vital organs
Blood: transport gases, nutrients, waste; Four elements of blood:
Erythrocytes Red cells
Leukocytes - white cells immune system
Platelets: blood clotting, produced in bone morrow
Plasma - 90% water.
Muscle Tissue
Fibrous proteins gives the muscle stripes.

Skeletal - voluntary (looks like slits)attached to the bone, closely connected. Indvidual cells are called muscle fibers, very, very thin and long, they contain myofibrils

Cardiac - one nucleous per cell, involuntary connected end to end (only in the heart)Sinoatrial Node the pacemaker, give it spontanoeus activity (rate that your heart will beat. not closely attached cells., gaps in between cell for communication. has a nucleious, depends on calcium

Smooth muscle - no strips. looks smooth. located in intestines, blood vessels, involuntary. closely attached, slow contractions by Autonomic Nervous Sytem. (bladder is the exception)
4 major parts, specalized for reception.

Dendrites - Rec Signal

Axon - carries signal to synaptic terminals.

cell body - maintains intgrety

Synaptic - carries signal to other cells
The outer most of the three primary germ layers of the embryo, from which the skin, nerve tissue and sensory organs develop.
Organ systems, Organs, & Tissues make up the Digestive System
The animal body contains organ systems, each composed of several organs, which are in turn composed of several types of tissue.
Organ systems consist of 2 or more interacting organs.
Organ systems: Digestive, urinary, immune, respiratory, circulatory, nervous, muscular, skeletal, endocrine, reproductive
External epithelia: your skin is really an organ
Mammalian skin, a representative organ, in cross section
Dermis permeated by arterioles. Arterioles feed blood pumped from the heart into a dense network of capillaries that nourish both derma & epidermal tissue..
exert a force by coordinated contraction (made up of fibers, different amt of fibers used based on what you are trying to do.
provides a support framework (light and rigid)
Contractile cylinders that extend the length of the fiber
Each myofibril is surrounded by a sarcoplasmic reticulum containing lots of Calcium ions (Ca2+)
plasma membrane of each muscle fiber
is periodically indented close to the sarcoplasmic reticulum of the myofibrils and the indentations are called T tubules
Skeletal Muscle Structure
A muscle is surrounded by connective tissue and attached to bones by tendons. It contains from a few to thousands of muscle cells called muscle fibers, often packaged into bundles within the muscle. Each fiber is packed with cylindrical subunits called myofibrils, which contain thick and thin filaments of protein.
Myofibril Structure and function
The myofibril is organized into a series of subunits called sarcomeres that show precise arrangements of two special protein filaments that interact to cause a contraction.

Thin filaments are made of actin and some accessory proteins

Thick filaments made of myosin; lie in between thin filaments

Myosin is capable of making temporary connection to actin with structures called cross-bridges

This interaction starts the contraction process which shortens the sarcomere
Myofibril Structure and function
The myofibril is organized into a series of subunits called sarcomeres that show precise arrangements of two special protein filaments that interact to cause a contraction.

Thin filaments are made of actin and some accessory proteins

Thick filaments made of myosin; lie in between thin filaments

Myosin is capable of making temporary connection to actin with structures called cross-bridges

This interaction starts the contraction process which shortens the sarcomere
Myofibril Structure and function (cont)
The myofibril is organized into a series of subunits called sarcomeres that show precise arrangements of two special protein filaments that interact to cause a contraction.

Thin filaments are attached to Z lines that separate each sarcomere subunit

The regular arrangement of thick and thin filaments and Z lines in each myofibril gives the striped appearance to each muscle fiber
Muscle fiber, myofibril, sarcomeres and filaments
(a) Each muscle fiber is surrounded by plasma membrane that burrows inside, forming T tubules. The sarcoplasmic reticulum surrounds each myofibril within the muscle cell. (b) Each myofibril consists of a series of subunits called sarcomeres, attached end to end by proteins called Z lines.
myofibril, sarcomeres
(b) Each myofibril consists of a series of subunits called sarcomeres, attached end to end by proteins called Z lines. (c) Within each sarcomere are alternating thick and thin filaments, which can be connected by cross-bridges (projections of the myosin molecules that make up the thick filaments).

(a) Repeated cycles of cross-bridge attachment, bending, release, and reattachment result in muscle contraction
The Neuromuscular Junction
Motor neurons connect the brain to a muscle or parts of a muscle.

The brain determines the frequency and number of fibers stimulated, this determines the degree of contraction of the muscle.

The action potential is the signal from the brain to the muscle

(a) Diagram of a neuromuscular junction in cross section. Action potentials in the motor neuron stimulate the muscle fiber membrane, which lies in folds beneath the terminal.
The Neuromuscular Junction cont.
The action potential is transferred into the muscle fiber and passes down the T tubules:

Causes sarcoplasmic reticulum to release Calcium ions (Ca2+)

The Ca2+ unlocks the binding sites on actin

Myosin cross-bridge initiates contraction using ATP for energy

(a) Diagram of a neuromuscular junction in cross section. Action potentials in the motor neuron stimulate the muscle fiber membrane, which lies in folds beneath the terminal.
The Human Skeleton
Vertebrate skeleton functions
Supports the body and protects internal organs (rib cage)

Attachment site for muscles

Produces blood cells

Storage site for calcium and phosphorus

Assists sensory transduction—middle ear bones, jaw bone

The human skeleton, showing the axial skeleton (tinged in blue-gray) and the appendicular skeleton (bone color).
The Human Skeleton cont
Vertebrate skeleton functions
Skeleton made up of two components
A. Cartilage
B. Bone
Both types are living cells embedded in a matrix of collagen

The human skeleton, showing the axial skeleton (tinged in blue-gray) and the appendicular skeleton (bone color).
Cartilage Structure and Function
Cells are called chondrocytes and secrete a flexible elastic matrix of extra-cellular collagen that binds the cells together.
Provides flexible support—ears, nose, trachea, larynx, bronchi
Connects bones but provides flexibility — ribs joined to sternum
Provides shock absorbency
Covers the ends of bones at joints
Pads in the knees, inter-vertebral discs
Bone Structure and function
Bones are organized into two parts:

Outer shell of compact bone that is hard, strong and dense, attaches to muscle tendons

Inner spongy bone that is porous, light and filled with blood vessels and bone marrow

There are three bone cell types:
Osteoblasts – new bone cells, by secreting calcium phosphate into collagen
Osteocytes – old bone cells trapped with hardened bone but alive and interconnected
Osteoclasts – bone dissolving cells, work to re-model bones in response to demands. 5-10% of bone mass re-modeled per year . Work with osteoblasts to form osteons, a basic unit structure of compact bones, and to repair fractures
Bone Structure and function cont.
2. Bone marrow
makes red & white blood cells, platelets
Storage and regulation of calcium and phosphorus levels via blood stream
Some fat storage
The Structure of Bone
Osteoblasts and osteoclasts routinely build osteons

They also repair bone fractures

(a) A typical bone, such as those in the arms and legs, is made of an outer layer of compact bone and spongy bone inside. For simplicity, blood vessels are not shown. (b) Osteons are clearly visible in this micrograph. Each includes a central canal containing a capillary. The capillary nourishes the osteocytes, embedded in the concentric rings of bone material.
Hinge Joint
Ligaments and cartilage provide stability for the joint so the muscles can work smoothly

Muscles and tendons move the bones.

Tendons are elastic and store energy to balance muscle effort

Muscles work in opposition at joints for balance and control

The human knee—a hinge joint—showing antagonistic muscles (here, the biceps femoris and the quadriceps of the thigh), tendons, and ligaments. (The tendon of the biceps femoris has been cut for viewing purposes.) The complexity of this joint, coupled with the extreme stresses placed on it during activities such as jumping, running, or skiing, make it very susceptible to injury.
The Steps in Bone Repair
Temporary callus forms at fracture
Osteoclasts and osteoblasts form new bone
Osteoclasts dissolved fragments and broken areas
Osteoblasts and osteoclasts reconstruct new osteons
Osteoclasts then sculpt new bone into original shape
A sarcomere is made up of
Thick and thin filaments
A muscle fiber contracts because
a receptor potential causes release of Ca++
B. interaction of thick and thin filaments
C. ATP energy is released
The degree of a muscle’s contraction is dependent on
The number of muscle fibers stimulated
Which body structure is responsible for regulating calcium and phosphorus levels in the blood?
bone marrow
Osteoclasts are responsible for:
bone dissolution
Muscles cause appendages to move because the muscles are
in opposition.
Gas Exchange
Gases move in and out by bulk flow.

co2 and 02 exchange in lungs by diffusion

gases dissovled in blood are transported by bulk flow.

02 & co2 exchange in tussues by diffusion.
Features Facilitating Diffusion
Gas exchange depends on diffusion
Exchange surface must be moist, as gases have to be dissolved in water in order to diffuse

Very thin cells line respiratory surfaces

Large surface area in contact with the environment

Relatively easy for aquatic organisms; big challenge for terrestrial animals.
Evolution of Respiratory System
Evolutionary changes in respiratory system
Smaller organisms rely on diffusion through epidermis (flatworms)
Circulatory systems move gases around (annelids, molluscs)
Large animals evolved respiratory systems with very large surface areas for diffusion
Internalizing the respiratory systems kept the surfaces moist
Respiratory epithelia surface cells are very thin to facilitate diffusion
Gas Exchange cont
Aquatic environments
gills – increased surface area

Terrestrial environments
Integumentary exchange – Diffusion across body surface (worms)
Book lungs – Air enters air pockets that extend into blood
filled chambers (spiders)
Tracheae/Spiracles – internal tubes (insects)
Lungs – chambers (vertebrates)

The gill reaches its greatest complexity in the fish, where it is made of thin folds of tissue called filaments and is protected under the operculum, a bony flap. A one-way flow of water is maintained over the gill by the pumping of water through the mouth and out the opercular opening.
Exchanging Gases
Gills elaborately branched or folded

Lungs – chambers containing moist surfaces

The gill reaches its greatest complexity in the fish, where it is made of thin folds of tissue called filaments and is protected under the operculum, a bony flap. A one-way flow of water is maintained over the gill by the pumping of water through the mouth and out the opercular opening.
Mechanics of Breathing
Mechanics of breathing: bulk flow of gases into animal
Inspiration — active inhalation of air
Frogs gulp; reptiles move guts
Mammals breathe with chest muscles that create negative pressure
Diaphragm and rib muscles contract, making the chest cavity larger
Chest expansion causes the lungs to expand; vacuum draws in air

Expiration — occurs when muscles relax
Flexible cartilage that connects the ribs to the sternum returns to normal position and this compresses lungs to help expel air

(a) During inhalation, rhythmic nerve impulses from the brain stimulate the diaphragm to contract (pulling it downward) and the muscles surrounding the ribs to contract (moving them up and outward). The result is an increase in the size of the chest cavity, causing air to rush in. (b) Relaxation of these muscles (exhalation) allows the diaphragm to dome upward and the rib cage to collapse, forcing air out of the lungs.
Control of respiration
Regulation of breathing by carbon dioxide CO2 levels in the blood.

Respiration center in brain: medulla generates nerve impulses that stimulates contraction of diaphragm and chest muscles

Respiration center tries to maintain a constant level of CO2 in the blood
Control of respiration cont.
CO2 level in the blood monitored by CO2 receptors in medulla

Elevated CO2 levels in blood signals need for more O2, causing receptors in increase breathing rate.

Increase in activity levels initiates higher breathing before CO2 rise occurs in blood; anticipates demand
The Human Respiratory System
The conducting portion
Carries air to the lungs
Warms and moistens air moving through it
Structural parts:
nose and mouth, pharynx
Larynx and epiglottis (flap that closes when swallowing); vocal cords
Trachea; bronchi lead to lungs
In lungs, smaller bronchioles lead to alveoli where diffusion occurs

Ciliated epithelia (surface cells):
Lines the trachea, bronchi, and bronchioles
Filter dust particles & bacteria, passed up through trachea and expelled as mucus (phlegm) or swallowed
Smoke paralyzes cilia and so they cannot remove smoke residue
The Human Respiratory System cont.
(a) Air enters mainly through the nasal cavity and mouth and passes through the pharynx and the larynx into the trachea. The epiglottis prevents food from going down the trachea. The trachea splits into two large branches, the bronchi, which lead into the two lungs. The smaller branches of the bronchi, the bronchioles, lead to the microscopic alveoli, which are enmeshed in capillaries, where gas exchange occurs. The pulmonary artery carries deoxygenated blood (in blue) to the lungs; the pulmonary vein carries oxygenated blood (in red) back to the heart. (b) Close-up of alveoli (their interiors are shown in this cut-away section) and their surrounding capillaries.
The Human Respiratory System cont.
Gas exchange portion
Alveoli - site of gas exchange in the lungs
Alveoli have an enormous surface area (75 sq. m. or 800 sq. ft)
Small grape-like structures on the end of each bronchiole
Thin layer of moisture on the inside surface of each alveolus
Capillaries surround the alveoli, each are only one cell thick
Gas exchange occurs in alveoli, because gases dissolve in a thin layer of moisture on the lung side of the alveoli
Dissolved gases diffuse across alveoli membrane into adjacent capillary membrane
Pulmonary arteries deliver deoxygenated blood from heart
Pulmonary veins return oxygenated blood to heart
Mechanisms of gas exchange and transport
The simple story of gas exchange in alveoli:
CO2 diffuses out of blood where [CO2] is high, into the air in alveoli, where [CO2] is low.
O2 diffuses from air where [O2] is high into the blood, where [O2] is low.

The real story:
Absorption of oxygen from plasma by hemoglobin in the RBC maintains a low concentration of oxygen dissolved in blood plasma, forcing diffusion of oxygen into blood plasma.
Carbon dioxide is actually transported in blood to lungs in three forms:
attached to hemoglobin (20%)
dissolved in blood plasma as a gas (10%)
dissolved as bicarbonate ions (70%)
The diffusion of carbon dioxide out of the blood plasma and RBC into alveoli changes the shape of hemoglobin molecules allowing it to absorb the maximum amount of oxygen
Gas Exchange between Alveoli and Capillaries
The alveoli and capillary walls are only one cell thick, very close to one another, and the cells are coated in a thin layer of fluid. This allows gases to dissolve and diffuse easily between the lungs and circulatory system.
Gas Exchange: Transport of Oxygen from lungs
O2 diffuses through lung capillary wall

O2 carried to tissues bound to hemoglobin

O2 diffuses through tissue capillary wall
Gas exchange in the body tissue capillaries
What happens at the body tissue capillaries to force oxygen into tissues and carbon dioxide out?
The simple story:
High concentration of CO2 in tissues is forced into blood by diffusion
High concentration of O2 in blood forces it into tissues by diffusion
The real story:
Enzymes in red blood cells convert dissolved carbon dioxide in plasma to bicarbonate, lowers dissolved plasma CO2 levels creating a concentration gradient, enhances diffusion of CO2 into blood
The rising CO2 level in blood force it to bind with hemoglobin, changing the molecules shape and forcing it to dump O2 which raises dissolved levels, enhancing diffusion out of blood to tissues
Gas Exchange: Transport of Carbon Dioxide
1a Dissolves in plasma,
due to low concentration

1b Converted to bicarbonate in RBC

1c Bound to hemoglobin.

CO2 diffuses through tissue capillary wall

CO2 is carried to the lungs

3.CO2 diffuses through lung capillary wall, bicarbonate is converted back to CO2
Respiration problems
Smoking: results in lung cancer and emphysema

Asbestos: causes lung cancer

Carbon Monoxide: colorless and odorless gas that binds to
hemoglobin and prevents oxygen absorption at very low
concentrations. A silent killer….

Allergens and asthma: many triggers in the environment
Respiration Diseases


Alveoli breakdown
Cigarettes, marijuana
Second-hand smoke

Lung cancer

Cystic fibrosis
Vertebrate Circulatory System: Functions
Transport O2 and CO2 - gases from the respiratory system
Distributes nutrients - from digestive system to body
Transports waste - cells to excretory system (kidney and liver)
Distributes hormones - from endocrine glands & other organs
Regulates body temperature – adjust blood flow
Protection against disease and blood loss - delivery of white blood cells to fight infections; clotting agents to wounds
Circulatory System Basics
Circulatory systems have three majors parts:
1. Fluid — blood
oxygen, wastes and other components
2. System of channels — blood vessels
arteries, veins, capillaries
Conduct blood throughout the body

3. A pump — the heart
Circulates blood through the vessels and throughout the body
Types of Circulatory Systems
Open systems
Open space within the body cavity—hemocoel
Arthropods (insects, spiders, and crustaceans)
Most mollusks (snails and clams)
Heart & vessels
Closed Systems
Confined blood in continuous vascular network
Pumping heart & vessels
Some invertebrates (earthworm, cephalopod molluscs)
All vertebrates

In hemocoel, tissues & organs directly bathed in blood.
Open: heart valves shut, forces blood into hemocoel, relaxes and blood drawn back into vessels/heart
Closed: more rapid flow more efficient transport of wastes & nutrients and higher blood pressure than in open CS
Vertebrate Circulatory System
The Heart
Muscular organ capable of strong contractions to force blood to flow

Works continuously

About 2 billion beats in an animals life time

Heart pumping sustains blood pressure throughout animal body
Vertebrate Circulatory System cont.
Heart Structure
Atria –collect blood from venous system
sends blood to ventricles

Ventricles- send blood to lungs and body

Greater complexity in heart structure among vertebrates due to challenges of life on land (larger heavier bodies)
Evolution of heart structures
Fish circulatory system
Heart (atrium & ventricle)
Low level of oxygen delivery

Amphibian and reptile circulatory system
Start of double circulation system that increased pressure to body capillaries
Two atria, one ventricle
Inefficient mixing of venous and arterial blood, reduced oxygen levels sent to body
Reptiles have partial septum dividing ventricle

Mammal and Bird circulatory system (+ crocodiles)
Complete separation of arterial and venous blood (double circulation)
Separate loop from heart to body capillaries allows for higher pressure
keeps oxygen levels at the maximum
2 atria, 2 ventricles
The Evolution of the Vertebrate Heart
(a) The earliest vertebrate heart is represented by the two-chambered heart of fishes. (b) Amphibians and most reptiles have a heart with two atria, from which blood empties into a single ventricle. Many reptiles have a partial wall down the middle of the ventricle. (c) The hearts of birds and mammals are actually two separate pumps that prevent mixing of oxygenated and deoxygenated blood. Note that in this and in subsequent illustrations, oxygenated blood is depicted as bright red, while deoxygenated blood is colored blue.
Human Heart
The heart is drawn as if it were in a body facing you, so that right and left appear reversed. Note the thickened walls of the left ventricle, which must pump blood much farther through the body than does the right ventricle, which propels blood to the lungs. One-way valves, called semilunar valves, are located between the aorta and the left ventricle, and between the pulmonary artery and the right ventricle. Atrioventricular valves separate the atria and ventricles.

Vena Cava
R. Atrium
R. Ratrioventricular Valve
R. Ventrical
R. Smiluar Valve
Pulmonary Artery

Pulmonary Veins
L. Atrium
L. Ratrooventricular Valve
L Ventrical
L Semiluar Valve
The heart and its functions
The heart beats about 100, 000 times a day.

The cardiac cycle
Both atria contract at the same time
A fraction of a second later the ventricles contract at the same time
Then the atria and ventricles relax and cycle starts again
One-way valves make sure blood goes the right direction
Measuring blood pressure
Systole — period of ventricle contraction
Diastole — relaxation of all the chambers
The Cardiac Cycle
Systole: Ventricles contract

Diastole: Heart relaxes; atria fill passively
Measuring Blood Pressure
Cuff inflated until no pulse audible
Pressure released until pulse is first heard
Cuff pressure is just lower than left ventricle
Continue deflating cuff till pulse inaudible
Cuff pressure less than lowest arterial pressure
Report pressures as: Systolic : Diastolic, 140:80

Blood pressure is measured with an inflatable blood pressure cuff and a stethoscope. The cuff is inflated until its pressure closes off the arm’s main artery, blood ceases to flow, and no pulse can be detected below the cuff. Then the pressure is gradually reduced. When the pulse is first audible in the artery, the pressure pulses created by the contracting left ventricle are just overcoming the pressure in the cuff and blood is flowing. This is the upper reading: the systolic pressure. Cuff pressure is then further reduced until no pulse is audible, indicating that blood is flowing continuously through the artery and that the pressure between ventricular contractions is just overcoming the cuff pressure. This is the lower reading: the diastolic pressure. The numbers are in millimeters of mercury, a standard measure of pressure also used in barometers.
Coordination of heart muscle cells
Heart composed of cardiac muscle tissue cells
Smooth coordinated contraction of heart muscle cells controlled by electrical signals (impulses) between muscle cells
Impulses cross between cells through gap junctions

Cardiac muscle cells are branched. Adjacent plasma membranes meet in folded areas that are densely packed with gap junctions (pores), which connect the interiors of adjacent cells. This arrangement allows direct transmission of electrical signals between the cells, coordinating their contractions.
Coordination of Heart Activity
Atrioventricular and semilunar valves
Sinoatrial node (SA node): pacemaker
Atrioventricular node (AV node)
Influences on heart rate
Parasympathetic nervous system - decreases heart rate
Sympathetic nervous system - increases heart rate
Coordination of Heart activity cont.
Sinoatrial node (SA node or pacemaker)
Sends electrical impulse that starts contraction of left and right atria
Impulse travels to atrioventricular node (AV node)
Signal from SA to AV is delayed by about 1/10 th of a sec.
Enough time for blood to leave atria and fill ventricles
Impulse continues along excitable fibers (i.e., bundle of His to Purkinje fibers) to ventricles, which contract together

Influences on heart rate –SA beat is about 100 per minute
Parasympathetic nervous system - decreases resting heart rate (70)
Sympathetic nervous system - increases heart rate during exercise (120). Caused by hormones - epinephrine or adrenalin
The Heart’s Pacemaker and Its Connections
The sinoatrial (SA) node, a spontaneously active mass of modified muscle fibers in the right atrium, serves as the heart’s pacemaker. The signal to contract spreads from the SA node through the muscle fibers of both atria, finally exciting the atrioventricular (AV) node in the lower right atrium. The AV node then transmits the signal to contract through bundles of excitable fibers that stimulate the ventricular muscle.

One impulse from the SA node starts the cycle

AV Node triggers the fibers to contract the ventricles

Heart attacks disrupt the cycle and fibrillation occurs

Defibrillators reset pacemaker
Composition of Blood
Plasma—55% to 60% of blood volume
90% water, yellowish
Three important proteins
Albumins maintain osmotic pressure in arteries, veins
Globulins transport nutrients, help immune system
Fibrinogen helps form blood clots
Blood Cells
Blood cells
Make up about 40-45% of blood volume, three types of cells:

Red blood cells (RBCs) — erythrocytes, 99% of the total cellular component in the blood
Carry O2 bound to hemoglobin molecules in cell
Each hemoglobin can carry 4 oxygen molecules, greatly enhancing capacity of blood
Hemoglobin binds O2 in lung capillaries [O2] high
CO2 Hemoglobin releases O2 in tissues [O2] low
A molecule of hemoglobin is composed of four polypeptide chains (two pairs of similar chains), each surrounding a heme group. The heme group contains an iron atom and is the site of oxygen binding. When saturated, each hemoglobin molecule can carry four oxygen molecules (eight oxygen atoms).
Blood cells cont
Red blood cells are made in bone marrow
Mammalian RBC’s lose their nuclei and live only about 120 days
Dead cells are recycled in the liver and spleen, especially to retrieve the iron

Body has a negative feedback system to ensure that enough red blood cells are present
The system initiates RBC production in the bone marrow and then shuts it off
Started when not enough oxygen is present (blood loss, high altitude)
Kidney produces a hormone called erythropoietin
Hormone production is stopped when adequate oxygen is available
RBC Regulation by Negative Feedback
Red blood cell regulation by negative feedback (change initiates series of events that counteract changes and restores original state)
The other blood cells
White blood cells—leukocytes (WBCs) and lymphocytes
Made in bone marrow
Five white blood cell types - attack bacteria and viruses as part of the immune system
WBC can operate outside of capillaries to attack bacteria and viruses
Act like amoeba and engulf foreign particles, then die & turn to pus.
Lymphocytes make antibodies for immune system

Cellular fragments from megakaryocyte
Produces n bone marrow
Function in blood clotting
Live only 10-12 days
Blood clotting mechanism
Platelets respond to irregularities in blood vessel walls, such as a tear or cut etc.

Platelets adhere to tear and starts a sequence of events

An enzyme , thrombin, converts the dissolved protein fibrinogen in blood plasma to stringy insoluble fibrin

The mesh of fibrin traps RBCS and more platelets

Platelets contract pulling web of cells and fibrin tighter and starts pulling injured tissues together so that they can heal.

Fibrin mesh and RBCs form the hard scab on top of wound
Blood Clotting cont
(a) Injured tissue and adhering platelets cause a complex series of biochemical reactions among blood proteins. These reactions produce thrombin, which catalyzes the conversion of fibrinogen to insoluble fibrin strands.
Blood Clotting (b)
(b) Threadlike fibrin proteins produce a tangled sticky mass that traps red blood cells and eventually forms a clot.
Blood Vessels
Arteries and arterioles
Thick walled, elastic to withstand high pressure
Carry blood away from the heart
Tiniest vessels; thin, single-cell wall for easy diffusion
Exchange of materials between blood & body cells
Venules and veins
Thin-walled vessels surrounded smooth muscle
Low resistance to blood flow
Return blood to the heart

Blood flow regulated by muscular walls of arterioles Influenced by:
Autonomic nerves: usually in response to heat, cold, exercise
Other chemicals released from nearby tissues
Distribution of Blood Flow
Regulated by muscular walls of arterioles
Aterioles determine blood pressure
Influenced by:
Autonomic nerves
Other chemicals released from nearby tissues
The Human Circulatory System
Most veins (right) carry deoxygenated blood to the heart, and most arteries (left) conduct oxygenated blood away from the heart. The pulmonary veins (carrying oxygenated blood) and arteries (carrying deoxygenated blood) are exceptions. All organs receive blood from arteries, send it back via veins, and are nourished by capillaries (only lung capillaries are illustrated and these are greatly enlarged, since capillaries are microscopic).
Muscles and connective tissues allow for regulation of blood pressure and flow
sphincters control blood flow into capillaries

Arteries and arterioles are more muscular than are veins and venules. Capillaries have walls only one cell thick. Oxygenated blood moves from arteries to arterioles to capillaries. Capillaries empty deoxygenated blood into venules, which empty into veins. The movement of blood from arterioles into capillaries is regulated by muscular rings called precapillary sphincters.
Distribution of Blood Flow
Tiniest vessels; thin, single-cell wall for easy diffusion
Blood flow very slow to help diffusion
RBC’s pass through capillary in single file.

Three forces at work to move gases and nutrients in and out of capillary via interstitial fluid and then to body cells
Concentration gradient: gas exchange with oxygen and carbon dioxide switching places by diffusion from high to low. Same for nutrients
High hydrostatic pressure on arterial side forces out plasma fluid containing small ions, nutrients.
Leaves behind large proteins, blood cells; lowers osmotic pressure
Osmosis brings waste products & water in on venous side
Exchanges in capillary
High hydrostatic pressure on arterial side forces out plasma fluid containing small ions, nutrients

Concentration gradients:
High O2 and nutrients in blood
Low O2 and nutrients in blood
High CO2 and wastes in tissues
Lymphatic System
(a) Lymph vessels, lymph nodes, and two auxiliary lymph organs, the thymus and spleen. Lymph is returned to the circulatory system by way of the thoracic duct, which empties into the vena cava, a large vein. (b) A cross section of a lymph node. The node is filled with channels lined with white blood cells (lymphocytes) that attack foreign matter in the lymph.
Lymph Capillary Structure
Lymph capillaries end blindly in the body tissues, where pressure from the accumulation of interstitial fluid forces the fluid into the lymph capillaries.
Plaques Clog Arteries
Diagrammatic cross section of an artery with a plaque. If the fibrous cap ruptures, a clot will form that can completely obstruct the artery, or the clot can break loose and clog a narrower artery “downstream.”