Animal Structure and Function Notes
Mrs. Laux
AP Biology
I. Unifying themes in study of animal anatomy (structure) and physiology
(function):
A. Form fits function
1. epidermal cells
2. small intestine length
B. Comparative Approach
1. how species of diverse evolutionary history adapted to own
environment
2. ex: frogsÆswimming sperm-human, as land mammals, how
deposit sperm?
3. ex: digestive tracts of herbivores as opposed to carnivores
C. Animals have ability to respond and adjust to environment
II. Animal Tissues
A. Functions of animal tissues and organs are a direct result of their
structure
1. atomsÆmoleculesÆmacromoleculesÆorganellesÆcells
(lowest level of organization that is considered alive
2. multicellular organisms:
cellsÆtissuesÆorgansÆorgan systemsÆorganism
3. TissuesÆgroups of cells with common structure and
function
a. classification of tissue is based on origin and
structure
b. categoriesÆepithelial, connective, muscular, nervous
B. Epithelial Tissue
1. sheets of tightly packed cells that cover outside of body and
line organs and body cavities
2. purposes: protect against injury, invading microbes
(infection), and fluid loss
3. other purposes include: absorption, secretion, and
sensation
4. one side of epithelium is always exposed
a. all materials must cross epithelium before being
considered “inside body”
b. ex: inhale air-must cross over respiratory membranealveoli-into blood before inside body
c. ex: eatÆfood enters body after absorbing through villi
of small intestine
5. some are specialized for additional roles:
a. some ciliatedÆex: lining of respiratory systemÆto
catch particles in air
b. mucous membranes
i. line oral, anal, and nasal cavities-open to
outside of body
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Animal Structure and Function Notes
Mrs. Laux
AP Biology
ii. secretes mucus (goblet cells) to lubricate
surfaces-traps
c. glandsÆsecrete hormones, enzymes, sweat, milk,
mucus, cerumen (wax), saliva, tears, sebum (oil)
d. sensory receptorsÆtaste buds
e. serous membranes
i. line a body cavity that does not open to the
outside of the body
6. attached to underlying tissue by a basement membrane
C. Connective Tissue
1. characterized by: a sparse cell population scattered through
an extensive intercellular substanceÆconsists of web of fibers
scattered throughout a matrix, a thin gel
a. 3 types of fibers-produced by fibroblasts
i. collagen-most numerous, most abundant
protein in body; great tensile strength-can be
stretched without tearing; changes to gelatin in
hot water
ii. elastin-structure that must stretch; branched,
fused to form networks
iii. reticular fibers-small, branched, form fine
networks; composed of collagen and
glycoproteins
2. function: support, connection, transport, storage,
cushioning
3. major types:
a. cartilage
i. protein matrix with cartilage cells
suspendedÆchondrocytes-lie in small cavities
called lacunae
ii. firm, yet elastic
iii. comprises skeleton of all vertebrate embryos
a. some vertebrates retain cartilaginous
skeleton (ex: shark)
b. most eventually replace cartilage with
bone
c. retain cartilage in areas such as nose,
ears, trachea, discs, and ends of some
bones
b. bone
i. matrix of collagen and calcium phosphate
ii. many cells interspersedÆex: osteocytesarranged in concentric layers called lamellae
iii. much harder than cartilage
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Animal Structure and Function Notes
Mrs. Laux
AP Biology
iv. long bonesÆonly outside is hard and compact,
inner area is filled with marrowÆspongy material
that manufactures blood cells
v. highly vascular-blood and nerves pass through
Haversian canals
vi. large, central marrow cavity with yellow
marrow-fat; red marrow-where blood cells are
produced
c. adipose tissue
i. found in subcutaneous layerÆfat layer beneath
skin that provides warmth and protection
ii. fat storing cells
iii. function: energy storage for later use
d. blood
i. matrixÆliquidÆplasma, which contains water,
salts, and proteins
ii. cellular components:
a. leukocytes (WBCs)
Æimmune defense
b. erythrocytes (RBCs)
Ætransport oxygen
c. platelets (parts of cells)
Æblood clotting
e. lymphi. picks up interstitial fluid; gets it back into
bloodstream
4. minor types
a. mast cells
i. release histamines during allergic reactions
b. plasma cells
i. secrete antibodies
D. Muscle Tissue
1. consists of long, excitable cells (=fibers); capable of
contraction
2. most abundant tissue in animals
3. 3 types of vertebrate muscle tissue:
a. skeletal muscle
i. voluntary movements
ii. attached to bones by tendons (connective
tissue)
iii. striated
b. cardiac muscle
i. involuntary muscle
ii. walls of heart
iii. striated and branched
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Animal Structure and Function Notes
Mrs. Laux
AP Biology
iv. intercalated discs, specialized junctions where
the fibers form
c. visceral (smooth) muscle
i. involuntary
ii. unstriated
iii. lines walls of internal organs
E. Nervous Tissue
1. senses stimuli and transmits signals from one point of an
animal to another
2. neuron=nerve cell
a. specialized to conduct an impulse or a bioelectrical
signal
b. consists of:
i. cell body
ii. dendrites (to)
iii. axons (away)
Æend in terminal branches
3. glial cells support and nourish the neurons
4. synapses-junctions between neurons where communication
occurs
F. Organ and Organ Systems
1. tissuesÆorgans in all but simplest animals
2. organsÆorgan systems
a. several organs with different functions that act in a
coordinated manner
b. organ systems of an organism are interdependent;
“whole is greater than the sum of its parts” (emergent
properties vs. reductionism)
G. Mechanisms that regulate an animal’s internal environment
1. all systems work together to maintain homeostasis
Æstate of equilibrium in which internal conditions
remain relatively stable
a. always being challenged by stressorsÆchanges in
internal or external environment
b. stresses are handled by:
i. receptorÆdetects change
ex: medulla, increasing H2CO3
ii. control centerÆprocesses information from
receptor and directs effector to respond
iii. effectorÆinitiates response
c. as control system operates, the effector’s response
feeds back and influences the magnitude of stimulus by
either:
i. depressing stimulusÆnegative feedback
a. stops or reduces intensity of original
stimulus
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Animal Structure and Function Notes
Mrs. Laux
AP Biology
b. ex: regulation of body temperature, blood
glucose levels
ii. enhancing stimulus (positive feedback)
a. enhances initial change
b. rarer
c. ex: blood clotting
childbirth/nursing
iii. desired condition referred to as set point
III. Body Temperature maintenance in animals
A. Thermoregulation
1. ability to maintain body temperature within certain limits
2. most animals cannot
B. Endotherms-“warm-blooded”
1. can thermoregulate
2. animals that generate their own heat metabolically
-ex: birds, mammals
3. requires more energy to sustain life
4. many are homeothermicÆbody temperature must be
maintained within narrow limits
5. many ways animals regulate temperature:
a. heatÆby-product of activity
b. hair, fat, feathersÆinsulation
c. shivering (muscle contractions)
d. sweat: change is endergonic; therefore, removes heat
when evaporates
e. blood vessels in skin: dilation (release heat) or
constriction (retain heat)
C. Ectotherms-“cold-blooded”
1. ex: fish, reptiles, amphibians, and invertebrates
2. acquire most body heat from environment; therefore, body
temperature is dependent on environment
3. body temperature and metabolic rate (amount of energy
used per unit of time) changes with environmental temperature
4. also called poikilotherms-“changing temperature”
D. Adjusting surface area to regulate body temperature
1. extremities of bodies (hands, feet, ears) add surface area to
body
2. by changing volume of blood that goes to these areas, heat
can be lost or conserved
a. vasodilationÆincreased diameter of blood vessels
b. vasoconstrictionÆdecreased diameter of blood
vessels
3. ex: Jack rabbits/elephants/fennec fox
a. in hot environments, increase blood flow to
extremities (ears) to lower body temperature
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Animal Structure and Function Notes
Mrs. Laux
AP Biology
b. in cold environment, reduce blood flow to conserve
heat
E. Other behavioral, physiological, or anatomical adaptations
1. ex: cold temperaturesÆhibernation, hair, feathers, blubber
2. ex: hot temperaturesÆsun to shade, activity only at night
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