Download Animal Structure and FUNction

A.P. BIOLOGY:
Animal Structure and FUNction
Basic Principles of Animal Form and Function: Chapter 40
Cells→ Tissues (epithelial, connective-bone, blood, cartilage, nervous, and muscle) → Organs→ Organ
Systems→ Body
Organ Systems: See Table 40.1, page 827
A. Respiratory System: (Chapter 42) Animals require O2 for aerobic respiration, so they need gas exchange.
They must also remove CO2 (which is a poison) from their body. They do this through RESPIRATION.
Respiration occurs in four forms:
1. Directly through the environment, where gases diffuse through cells (Platyhelminthes, Protists,
sponges, annelids, etc)
2. Gills: flaps of tissue (fish, mollusks, echinoderms, etc.). Countercurrent exchange between the
opposing movement of water and blood helps gases diffuse (Figures 42.20, page 885-886).
3. Tracheae: chitin lined tubes that have diffusion occur on their moist endings (insects) (page 887)
4. Lungs: cavities where gas exchange occurs.
Human Respiration (Figure 42.23, page 888):
Nose→ pharynx→ larynx→ trachea→ (flap of the epiglottis) → bronchi→ bronchioles→
alveoli→ GAS EXCHANGE
Oxygen comes in and Carbon Dioxide is expelled. CO2 is transported as bicarbonate ions in the
blood. High CO2 levels cause the blood to become acidic. This results in chemoreceptors sending
signals to the diaphragm to increase respiration.
The diaphragm and intercostal muscles control the movement of air into and out of the lungs.
Negative Pressure causes breathing: Diaphragm relaxes = exhale, Diaphragm contracts = inhale.
B. Circulatory System: (Chapter 42) The circulatory system distributes nutrients, oxygen, and wastes
throughout the body. There are two kinds of systems (Fig. 42.3, page 869):
1. Open Circulatory system: the internal cavity called a hemocoel bathes the tissues with a fluid
called hemolymph. The hemolymph returns to a pumping system (heart) through holes called
ostia (insects and mollusks).
2. Closed Circulatory system: The blood (nutrient, oxygen, and waste-carrying fluid) is confined to
vessels (annelids, and vertebrates)
Vessels: Arteries carry oxygenated blood away from the heart, arterioles
(smaller vessels) carry blood to capillaries where gas is exchanged. Venules return the blood to
the veins, which return the de-oxygenated blood to the heart.
Blood: Blood contains four key items:
1. Red blood cells (erythrocytes): transport oxygen
2. White blood cells (leukocytes): disease-fighting cells that defend body against infection
3. Platelets: cell fragments involved in blood clotting, release fibrin to stop blood flow
4. Plasma: liquid portion of blood
Heart Diagram:
Blood Flow through the Heart:
Inferior and Superior vena cava→ right atrium→ right atrioventricular valve (AV
valve or tricuspid valve)→ right ventricle→ pulmonary semilunar valve→ pulmonary artery→
lungs→ pulmonary veins→ left atrium → left AV valve→ left ventricle→ aortic semilunar
valve→ aorta→ body
Heart Control:
The SA (sinoatrial) node, the heart’s pacemaker, causes the heart to contract.
When ventricles contract (thy systole phase) blood is forced through the pulmonary arteries.
Then the ventricles relax (the diastole phase) the valves close. The closing of the AV valves
followed by the closing of the semilunar valves creates the “lub-dup” sounds of the heart.
The Heart beats approximately 70-100 beats per minute
Blood Pressure = pressure of blood against the vessels. The average blood pressure is 120/80.
AP Lab #10. See Page 877.
Comparative Circulatory Systems:
1. Sponges: Ameobocytes in the mesohyl carry nutrients from cell to cell
2. Gastrovascular Cavities: The fluid inside the cavity is continuous with the water outside, so the
tissues are bathed in fluid for gas and nutrient exchange.
3. Open and Closed Circulatory Systems:
4. Vertebrates (Fig. 42.4, page 879): Fish have a two-chambered hear, Amphibians have a threechambered heart, reptiles have a three and a half (four) chambered heart, crocodiles, birds and
mammals have a four-chambered heart.
C. Osmoregulation and The Excretory System: (Chapter 44) Regulates water balance and removes harmful
substances, such as nitrogen waste (fish-ammonia, mammals-urea, reptiles and birds-uric acid).
Osmoregulation is the absorption and excretion of water and dissolved substances that maintain water
balance (think fish). This is a delicate balancing act. Occurs in five ways.
1. Contractile Vacuoles: spaces in the cytoplasm that accumulate water and release it when needed
(protists like the paramecia and amoebas).
2. Flame cells: a branched tube system that permeates the body (Platyhelminthes). Fluids are
filtered across the flame cells whose cilia move it through the tube system (page 929)
3. Nephridia: in annelids, fluids enter the nephridia, pass through a collecting tubule, and are
excreted through pores (page 930).
4. Malpighian tubules: in arthropods, tubes attached to the midsection of the digestive tract collect
fluids. The fluids are deposited into the midgut where wastes are removed through the anus and
retained materials diffuse back into the body (page 930)
5. Kidneys: these organs contain about a million filtering tubes called nephrons. The kidneys
produce wasted fluids (urine) which pass to the ureters and enter into the bladder where they are
stored. The urine is excreted through the urethra (page 932)
The nephron:
There are three main parts to a nephron: Bowman’s capsule, convoluted tubule, and collecting
duct.
Three phases of the nephron:
1. Filtration: Blood enters the glomerulus, water and solutes get forced into the Bowman’s
capsule. This fluid is called filtrate and will travel to the convoluted tubule. Larger substances
(like blood cells) remain in the capillaries.
2. Secretion: The filtrate receives added fluid from the capillaries surrounding the nephron.
3. Reabsorption: The filtrate flows down the loop of Henle, where it becomes more concentrated
to do to flow of water out of the tubes. As it moves up the loop of Henle, the filtrate becomes
more dilute as salts move out of the tubule. The filtrate goes through the collecting duct and to
the renal pelvis. When it leaves the renal pelvis, it is concentrated urine.
Hormones: Two key hormones influence osmoregulation.
1. Antidiuretic hormone (ADH): increases the reabsorption of water, which makes urine more
salty.
2. Aldosterone: increases the reabsorption of water and sodium ions.
D. Digestive System: Chapter 41. Digestion is the chemical breakdown of food into smaller molecules.
The main stages of food processing are ingestion, digestion, absorption, and elimination
Four different groups of molecules are digested:
1. Starches: broken down into glucose
2. Proteins: broken down into amino acids
3. Fats: broken down into glycerol and fatty acid
4. Nucleic acids: broken down into nucleotides
The digestive process (Figure 41.15, page 855):
1. Mouth: Differentiated teeth chew food. Salivary amylase begins to breakdown starch into maltose.
Food is shaped into a ball (bolus) and then swallowed.
2. Pharynx: a.k.a. the throat. The epiglottis blocks the trachea so that food does not go down the
wrong pipe.
3. Esophagus: the tube that leads to the stomach. Contractions called peristalsis move the food down.
4. Stomach: Organ that secretes gastric juice (enzymes and hydrochloric acid). It has many functions:
a. Storage: holds excess amounts of food because it can expand.
b. Mixing: mixes food with water and gastric juice to produce a medium called chyme.
c. Physical breakdown: muscles churn the food, which physically breaks it down. Bacteria are
killed and proteins are weakened.
d. Chemical breakdown: Pepsin breaks down proteins. Stomach cells secrete a mucus layer to
protect their internal lining. Occasionally an ulcer will form when the lining is damaged.
e. Controlled release: Controls how much chime can enter into the small intestine. This is
controlled by a valve (pyloric sphincter).
5. Small Intestine: The first 25 inches of the small intestine (duodenum) continues the digestion of
starches and proteins. It begins the breakdown of fats and nucleotides as well. In the small intestine,
proteases digest proteins, maltase and lactase break down disaccharides, and phosphatases break
down nucleotides. The rest of the small intestine (six meters) absorbs the products of food. This
occurs through villi and microvilli which increase the surface area of absorption.
In the small intestine, other secretions are needed:
A. The pancreas: produces trypsin and other enzymes which enter the duodenum
through the pancreatic duct.
B. The liver: produces bile which emulsifies fats.
6. Large Intestine (colon): The main function is to reabsorb water to form solid waste, called feces.
Feces are stored in the rectum and secreted through the anus.
Comparative Digestion (page 854):
1. Intracellular Digestion: Food vacuoles fuse with lysosomes to digest food. (Sponges
2. Gastrovascular Cavity: Digests and distributes nutrients throughout the body. There is only one
entrance to the cavity (cnidarians, flatworms, etc)
3. Complete digestive tract (alimentary canal): Food moves in a single direction. Organisms have very
specific digestive tracts, depending on their dietary needs (crops and gizzards in earth worms; crops,
gastric ceca, midgut and hindgut in grasshoppers; crops, gizzards, and intestine in birds, etc)
E. Nervous System: (Chapter 48) The basic structural unit of the nervous system is a nerve cell, or
neuron. It consists of the following parts:
1. The cell body contains the nucleus and other cellular organelles.
2. The dendrite is typically a short, abundantly branched, slender extension of the cell body that
receives stimuli.
3. The axon is typically a long, slender extension of the cell body that sends nerve impulses.
Neurons can be classified into three general groups by their functions:
1. Sensory neurons (or afferent neurons) receive the initial stimulus.
2. Motor neurons (or efferent neurons) stimulate effectors, which are target cells that produce some
kind of response (like muscles, sweat glands, etc)
3. Association neurons (or interneurons neurons) are located in the spinal cord or brain and receive
impulses from sensory neurons or send impulses to motor neurons.
Neural transmission: depends on NA+ to reach action potential and K+ to restore itself.
Some of the common neurotransmitters and the kind of activity they generate are summarized below:
1. Acetylcholine is commonly secreted at neuromuscular junctions, the gaps between motor neurons
and muscle cells, where it stimulates muscles to contract. At other kinds of junctions, it typically
produces an inhibitory postsynaptic potential.
2. Epinephrine, norepinephrine, dopamine, and serotonin are derived from amino acids and are
mostly secreted between neurons of the central nervous system.
3. Gamma aminobutyric acid (GABA) is usually an inhibitory neurotransmitter among neurons in the
brain.
The nervous systems of humans and other vertebrates consist of two parts, as follows:
1. The central nervous system (CNS) consists of the brain and spinal cord.
2. The peripheral nervous system consists of sensory neurons that transmit impulses to the CNS and
motor neurons that transmit impulses from the CNS to effectors. The motor neuron system can be
divided into two groups, as follows:
--The somatic nervous system directs the contraction of skeletal muscles.
--The autonomic nervous system controls the activities of organs and various involuntary
muscles, such as cardiac and smooth muscles.
There are two divisions of the autonomic nervous system:
1. The sympathetic nervous system is involved in the stimulation of activities that prepare the body
for action, such as increasing the heart rate, increasing the release of sugar from the liver into the
blood, and other activities generally considered as fight-or-flight responses (responses that serve to
fight off or retreat from danger).
2. The parasympathetic nervous system activates tranquil functions, such as stimulating the secretion
of saliva or digestive enzymes into the stomach.
Comparative Nervous Systems (Page 1012)
F. The Muscular System: (Chapter 49) A skeletal muscle consists of numerous muscle cells called muscle
fibers. Muscle fibers have special terminology and distinguishing characteristics, as follows:
1. The sarcolemma, or plasma membrane of the muscle cell, is highly invaginated by transverse
tubules (or T tubules) that permeate the cell.
2. The sarcoplasm, or cytoplasm of the muscle cell, contains calcium-storing sarcoplasmic
reticulum, the specialized endoplasmic reticulum of a muscle cell.
3. Skeletal muscle cells are multinucleate. The nuclei lie along the periphery of the cell, forming
swellings visible through the sarcolemma.
4. Nearly the entire volume of the muscle cell is filled with numerous, long myofibrils. Myofibrils
consist of two types of filaments, as follows:
--Thin filaments consist of two strands of the globular protein actin arranged in a double helix.
--Thick filaments consist of groups of the filamentous protein myosin. Each myosin filament
forms a protruding head at one end.
Humans and other vertebrates have three kinds of muscles:
1. Skeletal muscle is attached to bones and causes movements of the body.
2. Smooth muscle lines the walls of blood vessels and the digestive tract where it serves to advance the
movement of substances.
3. Cardiac muscle is responsible for the rhythmic contractions of the heart.
Muscle Contraction Diagram:
Muscle contraction is described by the sliding-filament model which includes ATP and Ca2+.
G. The Immune System: (Chapter 43)
-The animal body must defend itself against the viruses, bacteria, and pathogens that are
found almost everywhere in our world.
-The body has three lines of defense: The first two are non-specific (innate immunity) and
the last line is specific (acquired immunity). SEE FIG. 43.1, pg. 899)
NON-SPECIFIC (Innate Immunity) RESPONSES:
1. The first line: The skin and mucus membranes provide both physical and chemical
defenses. Secretions like sweat, saliva, and tears contain antimicrobial proteins, like lysozyme, which is
an enzyme that digests the cell walls of many kinds of bacterial and thus destroys many bacteria entering
the upper respiratory tract and the openings around the eyes. Mucus traps microbes and the acidic pH of
the stomach kills most microbes before they enter the rest of the digestive tract.
2. The second line:
A. Phagocytic and Natural Killer Cells: Internal, nonspecific defense which depends on
phagocytosis (the ingestion of invading organisms by certain types of white cells).
 The phagocytic cells called neutrophils make up 60%-70% of all white blood cells (leukocytes)
 The neutrophils are summoned to infected cells by chemical signals (chemotoxis).
 Monocytes (make up 5% of leukocytes) are cells that begin in the blood and then enter into tissues
where they will develop into macrophages (big eaters). These macrophages are very effective and live
long lives. Some migrate and some are permanent parts of tissues (fixed).
 About 1.5% of leukocytes are eosinophils, which defend against large parasitic invaders.
 Natural Killer Cells destroy virus-infected body cells and abnormal cells rather than the pathogens.
They attack the cell’s membrane and cause it to burst.
B. The inflammation Response: FIG.43.6, pg. 902. Inflammatory responses occur when tissue is damaged by
physical injury or by the entry of microorganisms. At the injured area, precapillary arteries dilate and
postcapillary venules constrict, which increases the local blood supply.
 Chemical signals trigger the I.R. Histamine (made in white blood cells called basophils and also in mast
cells) is released by injured body cells and increases permeability of nearby capillaries. Prostaglandins
are substances that promote blood flow to the site of the injury. These chemical signals allow for the
arrival of blood clotting elements.
 With severe tissue damage, the body may mount a full scale attack, including an increase in leukocyte
production and sometimes a fever caused by pyrogens to inhibit growth of microorganisms.
C. Antimicrobial Proteins: Proteins that either attach microbes or stop the microbe reproduction.
 20 serum proteins, known as the complement system, carry out a cascade of steps leading to the lysis of
microbes.
 Interferons-secreted by virus-infected cells, these proteins diffuse to other cells and induce them to
produce other chemicals that will inhibit viral reproduction.
SPECIFIC RESPONSES:
-The third line: Lymphocytes respond to microorganism assault by creating selective and efficient immune
responses (See Figure 43.14, page 909)
 There are two main types of lymphocytes: B-lymphocytes (B cells) and T-lymphocytes (T cells).
 These lymphocytes display specificity and circulate throughout the blood.
 An antigen is a foreign molecule that brings about a specific lymphatic response.
 The B cells can release proteins called antibodies to respond to the antigen.
 B and T cells recognize different antigens by their antigen receptors. Each T or B lymphocyte has about
100,000 receptors for a specific antigen. There is a diversity of lymphocytes because of genetic
recombination during cell specialization.
 When a lymphocyte is activated, it produces two clones of cells: One clone (Effector Cells) include
short-lived cells that combat the antigen. The other clone cells (Memory Cells) are long-lived cells that
bear the same antigen receptors and can be used in future defensive actions. This cloning of
lymphocytes is called clonal selection. FIG 43.12, pg. 907.
 The first time the body is exposed to an antigen is called the primary immune response. It takes
between10-17 days from the initial exposure to an antigen for the lymphocytes to generate the best
effector cell response.
 During the primary immune response, some B and T cells make antibody-producing effector B cells
(called plasma cells) and T cells. While they are developing, the sick individual may feel ill, but
eventually the illness will get better as antibodies and effector T cells clear the antigen from the body.
 The secondary immune response occurs when the same individual is exposed to the same antigen. This
time the defense response is only about 2-7 days. This ability to generate secondary immune responses
is called immunological memory. Think chickenpox FIG. 43.7, pg. 846.
-Lymphocyte development (distinguishing self from non-self).
 Lymphocytes form from stem cells in bone marrow or in the liver of a fetus
 L’s that migrate from the marrow to the thymus develop into T cells
 L’s that remain in the bone marrow and mature there are called B cells
 L’s that bear receptors for molecules already present in the body are either rendered nonfunctional or
destroyed by programmed cell death. This leaves only L’s that will react to foreign molecules, and the
body has no remaining L’s that will react against itself. This is called self tolerance.
 Without self tolerance, autoimmune diseases, like multiple sclerosis, may develop.
**The major histocompatibility complex (MHC) is the protein fingerprint to each individual**
IMMUNE RESPONSES:
-There are two types of responses to antigens: A humoral response (B cell activation resulting from the
production and circulation of antibodies-defend against bacteria, toxins, and viruses in body fluid) and a
cell-mediated response (T cells become active against bacteria and viruses within infected body cells
and defend against fungi, protozoa, parasitic worms, and cancer). Helper T cells function in both
humoral and cell-mediated immunity.
IMMUNITY IN HEALTH AND DISEASE:
-Active Immunity: Immunity conferred by recovering from an infectious disease, such as chickenpox, caused by
the response of the infected person’s own immune system. This immunity is both naturally acquired and
can also be acquired by immunization (vaccination).
 Vaccines include inactivated bacterial toxins, killed microbes, parts of microbes, and weakened
microbes. These agents cannot cause disease, but they can act as antigens, stimulating an
immune response and immunological memory.
 Vaccinations have reduced the incidents of measles and whooping cough in children, and they
have led to the end of smallpox. Hopefully they will soon develop a vaccination for the HIV
virus.
-Passive Immunity: Antibodies are transferred from one individual to another. This occurs naturally, like when
a mother’s antibodies are passed to an infant through the placenta or breast milk. Passive immunity only
lasts for a few weeks to a few months, but it can still be helpful.
 Can be passed on artificially by injecting antibodies from an immune animal to another animal. For
example, a person bitten by a rabid animal may be injected with antibodies from other people who
have been vaccinated against rabies.
-Transfusions and Tissue Transplants:
 The immune system can distinguish between the body’s own cells and pathogens, but it can also
fight off the cells of other individuals.
 The ABO blood group: Flashback. Individuals with A blood have the A antigen. They will reject B
blood.
 Blood antibodies are preexisting and only cells of the type of blood that a person actually has will
not be destroyed.
 The Rh factor is a red blood cell antigen, Rh negative does not have the factor and Rh positive does
have the factor. May cause problems during pregnancy.
 The MHC is responsible for rejecting tissue and organ transplants. Matching the MHC of donators
and receivers is critical for success. Identical twins are very close and siblings may also have a
similar match.
 Often, suppressing medicines are prescribed in transplants to keep the body from rejecting the new
tissue or organs. This can leave the body susceptible to infection and cancer.
 In bone marrow transplants, the MHC must be matched because the graft itself, rather than the host,
is the cause of rejection. This is a graft versus host reaction.
-Abnormal immune functions can cause disease
 Allergies are hypersensitive responses to certain environmental antigens, called allergens. The most
serious consequences of an acute allergic response is anaphylactic shock, a life-threatening reaction
to injected or ingested allergens. Blood pressure drops and death can occur within a few minutes,
epinephrine can counteract this reaction.
 Autoimmune diseases occur when the immune system loses tolerance for itself. Lupus, rheumatoid
arthritis, and multiple sclerosis are examples of this. Much research is being done on this now.


Immunodeficiency diseases occur when the humoral or cell-mediated immune defenses become
deficient. In severe combined immunodeficiency (SCID), both systems fail to function. People may
be born with these diseases or they may develop later in life, like Hodgkin’s disease or AIDS. Some
scientists believe that physical and emotional stress can harm immunity.
AIDS: acquired immunodeficiency syndrome. People with AIDS are highly susceptible to
opportunistic diseases (infections and cancers that take advantage of a weak immune system).
G. The Endocrine System: (Chapter 45) The endocrine system produces hormones that help maintain
homeostasis and regulate reproduction and development. A hormone is a chemical messenger produced
in one part of the body that affects target cells in another part of the body. Hormones have the following
general characteristics:
1. Hormones are transported throughout the body in the blood.
2. Minute amounts of hormones can have significant influence on target cells.
3. Hormones may be steroids, peptides, or modified amino acids.
The two key endocrine glands are the hypothalamus (makes hormones and releasing factors) and
pituitary (“master gland, the size of a kidney bean)
There are two halves, or lobes, of the pituitary. Their special associations with the hypothalamus are
described below (pages 950-951):
1. Posterior pituitary-Two hormones, ADH (antidiuretic hormone) and oxytocin, are produced
by neurosecretory cells in the hypothalamus and are stored in the posterior pituitary and released
as needed.
2. Anterior pituitary-Releasing hormones are produced by neurosecretory cells in the
hypothalamus and secreted into the blood. This blood flows directly to the anterior pituitary
where the releasing hormones stimulate the release of tropic hormones produced in the anterior
pituitary. Tropic hormones are hormones whose target cells are other endocrine glands. Thus,
they regulate hormone production by other glands.
There are two methods by which hormones are known to trigger activities in target cells, as follows (pg.
946):
1. The hormone (usually a steroid) diffuses through the plasma membrane, through the cytoplasm,
and into the nucleus. The hormone binds to a receptor protein in the nucleus. The receptor
protein, in turn, activates a portion of the DNA that turns on specific genes.
2. The hormone (usually a peptide) binds to a receptor protein on the plasma membrane of the cell
(receptor-mediated endocytosis). The receptor protein, in turn, stimulates the production of
one of the following second messengers.
--Cyclic AMP (cAMP) is produced from ATP. Cyclic AMP, in turn, triggers an enzyme that
generates specific cellular changes.
--Inositol triphosphate (IP3) is produced from membrane phospholipids. IP3, in turn, triggers
the release of Ca2+ from the endoplasmic reticulum, which, in turn, activates enzymes that
generate cellular changes.
Key Hormone Table: Page 949
H. Reproductive System: (Chapter 46) Reproduction is the production of eggs and sperm along with the
processes leading to fertilization. Without Reproduction, there is no life!
There are two types of reproduction:
1. Asexual: The creation of new individuals whose genes all come from one parent without the
fusion of egg and sperm (by budding, fragmentation, regeneration, etc)
2. Sexual: The creation of offspring by fusion of haploid gametes to form a zygote.
i. Females can form two types of eggs: one is fertilized, the other develops without being
fertilized (parthenogenesis)
ii. Hermaphrodites have both male and female reproductive parts
iii. Internal fertilization occurs within the female reproductive tract, External fertilization
occurs when eggs are fertilized outside the body (in a moist environment)
Primary sex characteristics: structures directly involved in reproduction
 Males: Testes (Seminiferous tubules, scrotum), Epididymis, vas deferens, seminal
vesicles, prostate gland, Bulbourethral glands, and penis (page 971).
 Females: Ovary, fallopian tube, uterus, vagina (page 970)
Secondary sex characteristics: structures used to indicate sexual maturity. Body hair, breasts, voice,
fat deposits, etc.