1. C H A P T E R 4 0
Animal Form and Function

2. Size and Shape
o Anatomy – the biological form
of the animal
o Physiology – the biological
function of an animal
o Convergent Evolution – similar
forms for animals in the
same environment,
o Ex. Seals, penguins, tunas

3. Exchange with the Environment
o The ears of a jackrabbit are extremely
thin and large
o Provides the rabbit with a
efficient way to dissipate heat
from the blood vessels in the
ear to the air
o Surface Area to
Volume, higher is
more efficient

4. Organization of Body Plans
o Tissues – groups of cells with a similar
appearance and common function
o Organs – made up of tissues, a
functional unit
o Organ System – made up of
o ex: Skin is an organ of the
integumentary system, which
helps regulate body temperature
organs that work together

5. Tissues
o Epithelial Tissue – covers the outside of the
body, lines organs and cavities within the body
o Closely Packed, allowing them to function as a barrier
against mechanical injury, pathogens, and fluid loss
o Connective Tissue – holds other tissues and
organs in place
o Collagenous fibers – strong and flexible
o Reticular fibers – join connective tissue to other tissues
o Elastic fibers – provide elasticity, allowing something to
return to its original state

6. Signaling via Hormones
o A stimulus causes a cell to release a
hormone into the blood stream
o The signal travels everywhere through
the bloodstream
o Cells that have a receptor for that
hormone with generate a response
o Ex: When thyroid cells detect TSH, they
release another hormone, with prompts
cells to increase oxygen consumption and
heat production
o Relatively slow, takes time to move
throughout the body

7. Signaling via Neurons
o Nerve impulses go to a specific target
cell, rather than throughout the entire
body
o Travel along a path consisting of Axons
o Four types of cells can receive nerve
impulses: other neurons, muscle
cells, endocrine cells, and exocrine
cells
o Extremely fast effect compared to
hormones

8. Regulators and Conformers
o Regulator – for a particular environmental
variable, it uses internal mechanisms to control
internal change if that variable fluctuates
 Ex: a river otter, which keeps its temperature constant
o Conformer – allows its internal condition to
change in accordance with external changes
 Ex: large-mouthed bass, as the water warms or cools, so
does the temperature of the large mouthed bass
o Animals may regulate some conditions and let
others conform to the enviorment

9. Homeostasis
o Used to maintain a
“steady state” or internal
balance regardless of
external environment
o In humans, body
temperature, blood
pH, and glucose
concentration are each
maintained at a constant
level
o A buffer is a weak acid or
base used to maintain the
acidity (pH) of
a solution near a chosen
value

10. Homeostasis (cont.)
o Set point – a
particular value, seen
as a target
o A stimulus detected
by a sensor will trigger
a response
o This response is aimed
to return the variable
to the set point

11. Feedback Control
o Negative feedback – dampens a stimulus
shutting off the response
o Positive feedback – amplifies a stimulus
increasing the response
o ex:

12. The Circadian Rhythm
o circadian rhythm – governs physiological changes
that occur roughly every 24 hours
o Acclimatization – the set point changes gradually
 Ex, can offset the circadian rhythm slightly

13. Thermoregulation
o Endothermic animals generate heat by
metabolism
 Includes many birds and mammals
o Ectothermic animals gain heat from external
sources
 Includes most invertebrates, fishes, and amphibians
o This means that endotherms are regulators for
temperature, whereas ectotherms are
conformers for termperature
o Humans can dilate vessels to allow more blood
in and let heat radiate to the skin

14. Circulatory Adaptations
o Vasodilation – widening of superficial blood
vessels
o Used to cool down the animal
o Vasoconstriction – reduces width to slow blood
flow
o Used to keep the animal warm
o Countercurrent exchange – the transfer of heat
or solutes between fluids flowing in opposite
directions
o Ex. As warm blood flows from the body‟s core and cold
blood flows to the body‟s core, it maximizes heat
exchange

15. Countercurrent Exchange

16. Quantifying Energy Use
o Metabolic Rate – the sum of all the energy an
animal uses in a given unit of time
o kcalorie = 1000 calories or 4184 joules
o Fats: 9 Calories per gram
o Carbohydrates and Proteins: 4.5 – 5 Calories per gram

17. Metabolic Rate
o Smaller animals have higher metabolic rates per
gram than larger animals
o A mouse will use more
energy per gram than
an elephant would

18. Energy Conservation
 Torpor – a physiological state of decreased
activity and metabolism
 An adaptation that enables animals to save energy while
avoiding dangerous conditions
 Hibernation is a long term form of this that lets animals
„skip‟ over winter
 Metabolic rates during torpor can be 20 times
lower than they would be otherwise

19. Works Cited
o Pearson Education
o McGraw Hill Companies Inc.