Dat Biology- Animal Form And Function

Front 1

Animal tissues

Back 1

Epithelial, connective, muscle, nervous

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Ectotherms

Back 2

Animals that obtain body heat from their environment (body temp varies- poikilotherms). Includes most invertebrates, amphibians, reptiles and fish.

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Endotherms

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Animals that generate their own heat (also referred to as homeotherms because they maintain a constant internal temperature).

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How animals regulate their body temperature

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1. Cooling by evaporation- sweating and panting
2. Warming by metabolism- muscle contractions like shivering
3. Adjusting surface area to regulate temperature- extremeties (like ears in elephants) can have increased blood flow

Front 5

Gas exchange with the environment

Back 5

Seen in flatworms; animals are small enough to allow gas exchange directly with the outside environment. These animals typically have a large surface areaand every cell is exposed to either the outside environment or close enough that gas is available through diffusion.

Front 6

Gas exchange with gills

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Gills are evaginated structures that create a large surface area over which gas exchange can occur. A circulatory system inside removes the oxygen and delivers CO2. Countercurrent exchange also occurs.

Front 7

Gas exchange with tracheae

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Found in insects, tracheae are chitin-lined tubes that permeate their bodies. Oxygen enters through spiracles and diffusion occurs across moistened tracheal endings.

Front 8

Gas exchange with lungs

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Lungs are invaginated structures (cavities within the body). Book lungs occur in spiders.

Front 9

Gas exchange in humans

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1. Air enters the nose and passes through the nasal cavity, pharynx, and larynx.
2. Air enters the trachea (has the epiglottis, which covers the trachea and prevents food from entering)
3. The trachea branches into two bronchi which enter the lungs and the branch repeatedly to form bronchioles.
4. Each bronchiole branch ends in a alveolus, a sac densely surrounded by capillaries.
5. Gas exchange occurs by diffusion across the moist membrane of the alveoli. Oxygen eventually ends up in the red blood cells.
6. The circulatory system transports O2 through the body within RBC (O2 binds to hemoglobin)
7. Blood capillaries permeate the body and oxygen diffuses out of the red blood cells, across the walls, into interstitial fluid and across the cell membrane.
8. CO2 is transported in the plasma.

Front 10

Control of air flow in lungs

Back 10

Air is moved into and out of the lungs by changing their volume. This is controlled by the contraction of the diaphragm and intercostal muscles.

Front 11

Control of respiration

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Chemoreceptors are involved. Increased CO2 production causes a decrease in pH as CO2 is converted into HCO2 in the blood. In response to the acid, chemoreceptors send nerve impulses to the diaphragm and intercostal muscles to increase respiratory rate.

Front 12

Open circulatory system

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Pump blood into an internal cavity called a hemocoel which bathe tissues with hemolymph (oxygen and nutrient rich). The hemolymph returns to the heart through holes called ostia. *Occurs in insects and mollusks

Front 13

Closed circulatory system

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Blood is confined to vessels. Found in members of the phylum Annelida (earthworms), certain mollusks, and vertebrates.

Front 14

Path of blood in the body

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Deoxygenated blood enters the RIGHT ATRIUM and goes through the TRICUSPID VALVE to enter the RIGHT VENTRICLE. From here it is pumped to the lungs and oxygenated. Then it enters the LEFT ATRIUM and passes through the BICUSPID VALVE to the LEFT VENTRICLE to enter the AORTA as it goes to the body.

Front 15

Heart cycle

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1. SA node (pacemaker) initiates the cycle by contracting both atria and sending a delayed impulse to the AV node. Located in the upper wall of the right atrium.
2. The AV node sends an impulse through the Bundle of His and then through the Purkinje fibers. This results in the contraction of the ventricles (systole). Located in the lower wall of the right atrium.

Front 16

Blood composition

Back 16

Red blood cells- transport oxygen and catalyze the conversion of CO2 and H20 to H2CO3. Mature cells lack a nucleus to maximize hemoglobin content.
White blood cells- leukocytes, consist of five major groups of disease fighting cells that defend the body against infection
Platelets- cell fragments involved in blood clotting. Release the factors involved in converting fibrinogen to fibrin.
Plasma- the liquid portion that contains various dissolved substances.

Front 17

Osmoregulation

Back 17

The absorption and excretion of water and dissolved solutes so that proper water balance is maintained.

Marine fish- hypoosmotic to its environment and thus water is constantly lost by osmosis. Marine fish must constantly drink water.
Fresh water fish- hyperosmotic to their environment. Water constantly diffuses into the environment.

Front 18

Important excretory mechanisms

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1. Contractile vacuoles- found in the cytoplasm of protists; they fill with water and merge with the PM to release water into the environment
2. Flame cells- found in planaria, they are distributed along a branched tube system. Body fluids are filtered across the flame cells whose internal cilia move the fluids through the tube system. Wastes are excreted through pores.
3. Nephridia- occur in pairs within each segment of most annelids. Interstitial fluids enter and are concentrated before excreted.
4. Malpighian tubules- occur in many arthropods. Tubes attached to the midsection of the digestive tract and collect body fluids from the hemolymph that bathes the cells. These wastes are deposited into the midgut and wastes continue to be excreted through the anus.
5. Kidney- consists of millions of filtering tubes called nephrons. Two kidneys produce waste which passes to the bladder for temporary storage.

Front 19

Nephron

Back 19

Begins with Bowman's capsule, a bulb shaped body at one end. A branch of the renal artery enters, branches to form a dense ball of capillaries, and then exits.

Then the convoluted tubule is a winding tube that is shaped like a hair pin in the middle. Surrounding it is a dense network of capillaries that merge into the renal vein.

Finally, the convoluted tube empties into a collecting duct which descends toward the center of the kidney.

Front 20

Hormones involved in the excretory system

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1. ADH- increase reabsorption of water by the body and increase the concentration of salts in urine. Increases the permeability of the collecting duct to water.
2. Aldosterone- increases both the reabsorption of water and the reabsorption of Na+ by increasing permeability.

Front 21

Breakdown of macromolecules

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Starch- glucose
Proteins- amino acids
Fats- glycerol and fatty acids
Nucleic acids- nucleotides

Front 22

Digestion

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1. Begins in the mouth with salivary amylase which begins the breakdown of starch into maltose. Chewing reduces the size of food particles. Food is shaped into a bolus and swallowed.

2. When food is swallowed it passes through the pharynx and does not enter the trachea because of the epiglottis.

3. Food moves through the esophagus, the tube leading to the stomach. Move by muscular contractions (peristalsis)

4. The food enters the stomach, which secretes gastric juices (mix of digestive enzymes and HCl).

5. Small intestine- continues digestion of proteins and starches as well beginning the digestion of fats and nucleotides.

6. Large intestine- reabsorbs water to form solid waste.

Front 23

Functions of the stomach

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Storage, mixing to yield chyme, physical breakdown, chemical breakdown. Proteins are broken down by pepsin.

Front 24

Enzymes associated with the small intestine

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Small intestine: produces proteolytic enzyme (digests proteins), maltase and lactase, and phosphatase.
Pancreas: Produces trypsin and chymotrypsin (proteases), lipase, and pancreatic amylase (starch).
Liver: Bile (emulsifies fats)

Front 25

Hormones involved in the gastric process

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Gastrin: produced by the cells of the stomach lining either when food reaches the stomach or when the nervous system senses the availability of food. Stimulates other cells to produce gastric juices.
Secretin- produced by the cells of the duodenum. Stimulates the pancreas to produce bicarbonate.
Cholecystokinin-produced by the small intestine in response to the presence of fats. Stimulates the gall bladder to release bile and the pancreas to release its enzymes.

Front 26

Neuron constituents

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Cell body (Contains nucleus and other organelles), dendrite (short, branched, extension that receives stimuli), axon (sends nerve impulses)

Front 27

Three groups of neurons

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Sensory: (afferent) receive the initial stimulus
Motor: (efferent) stimulate effectors (the target cells that produce the response)
Association: (interneuron) Located in the spinal cord or brain and receive impulses from sensory neurons or send impulses to motor neurons.

Front 28

Resting potential

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The unstimulated, polarized state of a neuron (about -70 mV)

Front 29

Action potential

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In response to stimulus, gated ion channels in the membrane suddenly open and permit the Na+ on the outside of the cell to rush in. The charge on the cell becomes depolarized (more positive on the inside). The action potential travels down the length of the neuron as opened Na+ gates stimulate neighboring Na+ gates to open.

Front 30

Repolarization

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In response to the inflow of Na+ the K+ ion channels open as well, allowing K+ on the inside of the cell to rush out of the cell.

Front 31

Hyperpolarization

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By the time the K+ gated channels close, more K+ have moved out of the cell than is actually necessary to establish the original polarized potential. The membrane is at -80 mV

Front 32

Refractory period

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The membrane is polarized but the Na+ and K+ are on the wrong sides and thus the neuron will not respond to new stimulus. To reestablish the original distribution, Na+/K+ pumps are used.

Front 33

Chemical synapse

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-When an action potential reaches the end of an axon, the depolarization of the membrane causes gated channels to open and allow Ca2+ to enter.
-The influx causes synaptic vesicles to merge with membrane, releasing neurotransmitters into the cleft.
-Neurotransmitter binds with proteins on the postsynaptic membrane.
-The membrane is excited (Na+ gates open) or inhibited (K+ gates open)
-The neurotransmitter is broken down by enzymes and recycled

Front 34

Common neurotransmitters

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Acetylcholine- secreted at neuromuscular junctions (gaps between motor neurons and muscle cells) where it stimulates the muscle to contract.
Epinephrine, norepinephrine, dopamine, seratonin- derived from amino acids and secreted between the neurons of the CNS
GABA- inhibitory neurotransmitter among neurons in the brain

Front 35

Divisions of the nervous system

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1. Central nervous system (Brain and spinal cord)
2. Peripheral nervous system
-Somatic
-Autonomic
-Sympathetic
-Parasympathetic

Front 36

Sympathetic nervous system

Back 36

Involved in the stimulation of activities that prepare the body for action. This includes increasing heart rate, increasing the release of sugar from the liver into the blood.

Front 37

Parasympathetic nervous system

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Activates tranquil functions like digestion.

Front 38

Characteristics of muscle fibers

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1. Sarcolemma- PM of muscle cell
2. Sarcoplasm- cytoplasm of muscle cell
3. Multinucleate
4. Myofibrils (thin actin and thick myosin)

Front 39

Muscle contraction

Back 39

1. ATP binds to myosin and is converted to ADP + Pi
2. Ca2+ bind and exposes the binding site.
3. Cross bridges form between myosin and actin filaments
4. ADP + Pi are released and the two Z lines are pulled together, contracting the muscle.
5. When a new ATP molecule attaches to myosin, the cross bridge breaks

Front 40

Stimulation of muscle contraction

Back 40

-Action potential reaches the neuromuscular junction and acetylcholine is released.
-Receptors in the sarcolemma initiate a depolarization event and an action potential that travels through the transverse system of tubules
-Sarcoplasmic reticulum releases Ca2+
-The Ca2+ binds to troponin on the actin helix, and muscle contraction begins

Front 41

Kinds of muscle

Back 41

Skeletal- attached to bone, associated with body movement
Smooth muscle- lines walls of blood vessels and the digestive tract where it serves to advance movement of substances. Does not have the striated appearance of skeletal muscle. Contraction is controlled and relatively slow.
Cardiac- responsible for the rhythmic contractions of the heart. Although striated, cardiac muscle is highly branched and has gap junctions. Generates its own action potential which spreads by electric synapses.

Front 42

Skin

Back 42

First line of defense against invaders.
-Physical barrier (acidic and oily)
-Antimicrobial proteins are contained in saliva, tears, and other secretions
-Cilia line the lungs and serve to keep invaders out of the lungs
-Gastric juice kills most microbes
-Symbiotic bacteria found in the digestive tract outcompete any other organisms

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Second line of defense

Back 43

Involves:
Phagocytes- WBC that kill pathogens by phagocytosis.
Complement- a group of twenty proteins that complement defense reactions; attract phagocytes to foreign cells and destroy foreign cells by promoting lysis.
Interferons- substances secreted by cells invaded by viruses that stimulate neighboring cells to produce defense proteins.
-Inflammatory response

Front 44

Inflammatory response

Back 44

A series of events that occur in response to a pathogen.

-Histamine is secreted by basophils (WBC found in connective tissue)
-Vasodilation increases blood supply to the damaged area. This also causes redness, increase in temp, and swelling.
-Phagocytes are attracted by chemical gradients engulf pathogens and damaged cells.
-Complement helps phagocytes engulf proteins

Front 45

Third line of defense

Back 45

The immune response and it differs from the inflammatory response in that it targets specific antigens.

Front 46

MHC

Back 46

Major histocompatibility complex, the mechanism by which the immune system is able to differentiate between self and nonself cells. The MHC is a collection of glycoproteins that exists on the membranes of all body cells.

Front 47

Lymphocytes

Back 47

Primary agents of immune response; are WBC that originate in the bone marrow but concentrate in lymphatic tissues.

Includes:
B cells- originate and mature in bone marrow and respond to antigens. The PM surface has antibodies.
T Cells- originate in the bone marrow but mature in the thymus gland. Have antigen receptors (not antibodies) that are recognition sites for molecules displayed by nonself cells.

Front 48

Properties of antibodies

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Proteins, each antibody is specific for a particular antigen, there are five classes of antibodies (or immunoglobulins), each antibody is a variation of a basic Y shaped protein, and antibodies inactivate antigens by binding to them

Front 49

Daughter B Cells

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Plasma cells- release specific antibodies which then circulate through the body, binding to antigens
Memory cells- long lived B cells that do not release their antibodies in response to the immediate antigen invasion. Instead, they circulate the body and respond quickly to any subsequent invasion by the same antigen. Provides immunity.

Front 50

Two kinds of immune system responses

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1. Cell mediated- uses mostly T cells and responds to any nonself cell, including cells invaded by pathogens.
2. Humoral response- involves most cells and responds to antigens or pathogens that are circulating the lymph or blood

Front 51

Characteristics of hormones

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They are transported throughout the body in the blood and minute amount of hormones can have a significant influence on target cells. Also, hormones may be steroids, peptides, or modified amino acids.

Front 52

Posterior pituitary

Back 52

Stores ADH and oxytocin (produced by the hypothalamus)

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Anterior pituitary

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Produces tropic hormones whose release is stimulated by the secretion of releasing hormones in the hypothalamus.

Front 54

Beta cells vs. alpha cells

Back 54

Found in the islets of Langerhans.

Beta cells secrete insulin
Alpha cells secrete glucagon