1. Basic Principles of Animal Form and Function
Chapter 40
Basic Principles of Animal Form and Function

2. Anatomy is the study of the structure of an organism
Physiology is the study of the functions an organism performs

3. Concept 40.2: Animal form and function are correlated at all levels of organization
Most animals are composed of specialized cells organized into tissues that have different functions
Tissues are classified into four main categories: epithelial, connective, muscle, and nervous

4. LE 40-5_1 Simple Stratified columnar columnar epithelium epithelium
EPITHELIAL TISSUE
Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often located where secretion or active absorption of substances is an important function.
Simple
columnar
epithelium
Stratified
columnar
epithelium
Pseudostratified
ciliated columnar
epithelium
Cuboidal
epithelia
Stratified
squamous
epithelia
Simple squamous
epithelia
Basement membrane
40 µm

5. LE 40-5_2 Chondrocytes Collagenous fiber Loose connective tissue
120 µm
Chondrocytes
Collagenous
fiber
Loose
connective
tissue
Chondroitin
sulfate
Elastic
fiber
100 µm
Cartilage
Fibrous
connective tissue
Adipose tissue
Fat droplets
Nuclei
150 µm
30 µm
Blood
Central
canal
Red blood cells
Bone
White blood cell
Osteon
Plasma
700 µm
55 µm

6. LE 40-5_3 Multiple nuclei Skeletal muscle Muscle fiber Sarcomere
MUSCLE TISSUE
100 µm
Multiple
nuclei
Skeletal muscle
Muscle fiber
Sarcomere
Cardiac muscle
Nucleus
Intercalated
disk
50 µm
Nucleus
Smooth muscle
Muscle
fibers
25 µm
NERVOUS TISSUE
Neuron
Process
Cell body
Nucleus
50 µm

7. Organs and Organ Systems
In all but the simplest animals, tissues are organized into organs
In some organs, the tissues are arranged in layers

8. LE 40-6 Lumen of stomach Mucosa: an epithelial layer that lines the
Submucosa: a matrix of
connective tissue that
contains blood vessels
and nerves
Muscularis: consists
mainly of smooth muscle
tissue
Serosa: a thin layer of
connective and epithelial
tissue external to the muscularis
0.2 mm

10. Concept 40.3: Animals use the chemical energy in food to sustain form and function
All organisms require chemical energy for
growth
repair
physiological processes
regulation
reproduction

11. LE 40-7 Organic molecules in food External environment Animal body
Digestion and
absorption
Heat
Energy
lost in
feces
Nutrient molecules
in body cells
Energy
lost in
urine
Carbon
skeletons
Cellular
respiration
Heat
ATP
Biosynthesis:
growth,
storage, and
reproduction
Cellular
work
Heat
Heat

12. Quantifying Energy Use
Metabolic rate is the amount of energy an animal uses in a unit of time
One way to measure it is to determine the amount of oxygen consumed or carbon dioxide produced

13. LE 40-8
This photograph shows a ghost crab in a respirometer. Temperature is held constant in the chamber, with air of known O2 concentration flowing through. The crab’s metabolic rate is calculated from the difference between the amount of O2 entering and the amount of O2 leaving the respirometer. This crab is on a treadmill, running at a constant speed as measurements are made.
Similarly, the metabolic rate of a man fitted with a breathing apparatus is being monitored while he exercises on a stationary bike.

14. Bioenergetic Strategies
An animal’s metabolic rate is closely related to its bioenergetic strategy
Birds and mammals are mainly endothermic: Their bodies are warmed mostly by heat generated by metabolism
Endotherms typically have higher metabolic rates

15. Amphibians and reptiles other than birds are ectothermic: They gain their heat mostly from external sources
Ectotherms generally have lower metabolic rates

16. Activity and Metabolic Rate
The basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest
The standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest
Activity greatly affects metabolic rate

17. Maximum metabolic rate
LE 40-9
500
A = 60-kg alligator A H
100 H A
A = 60-kg human 50 H
Maximum metabolic rate
(kcal/min; log scale) 10 H 5 H A 1 A
0.5 A
0.1 1
second 1
minute 1
hour 1
day 1
week
Time interval
Key
Existing intracellular ATP
ATP from glycolysis
ATP from aerobic respiration

18. Endotherms Ectotherm 800,000 340,000 8,000 4,000 438 Human 233 Python
Annual energy expenditure (kcal/yr)
Basal
(standard)
metabolism
Reproduction
Temperature
regulation
Growth
Activity
60-kg female human
from temperate climate
4-kg male Adélie penguin
from Antarctica (brooding)
4,000
0.025-kg female deer mouse
from temperate
North America
4-kg female python
from Australia
8,000
Ectotherm
Total annual energy expenditures. The slices of the pie charts indicate energy
expenditures for various functions.
Energy expenditures per unit mass (kcal/kg•day). Comparing the daily energy expenditures per kg of body weight for the four animals reinforces two important concepts of bioenergetics. First, a small animal, such as a mouse, has a much greater energy demand per kg than does a large animal of the same taxonomic class, such as a human (both mammals). Second, note again that an ectotherm, such as a python, requires much less energy per kg than does an endotherm of equivalent size, such as a penguin.
Energy expenditure per unit mass
(kcal/kg•day)
438
233
36.5
5.5
Python
Human
Deer mouse
Adélie penguin

19. Concept 40.4: Animals regulate their internal environment within relatively narrow limits
The internal environment of vertebrates is called the interstitial fluid and is very different from the external environment
Homeostasis is a balance between external changes and the animal’s internal control mechanisms that oppose the changes

20. Mechanisms of Homeostasis
A homeostatic control system has three functional components:
a receptor
a control center
an effector
Animation: Negative Feedback
Animation: Positive Feedback

21. Negative Feedback Positive Feedback LE 40-11 Response No heat produced
Room
temperature
decreases
increases
Set point
Too
hot
Set
point
Heater
turned
off
cold
Control center:
thermostat on
Heat
Negative Feedback
Positive Feedback

22. Concept 40.5: Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior
Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range

23. Ectotherms and Endotherms
Ectotherms include most invertebrates, fishes, amphibians, and non-bird reptiles
Endotherms include birds and mammals
In general, ectotherms tolerate greater variation in internal temperature than endotherms

24. River otter (endotherm)
LE 40-12 40
River otter (endotherm) 30
Body temperature (°C) 20
Largemouth bass (ectotherm) 10 10 20 30 40
Ambient (environmental) temperature (°C)

25. Endothermy is more energetically expensive than ectothermy
It buffers the animal’s internal temperatures against external fluctuations
It also enables the animal to maintain a high level of aerobic metabolism

26. LE 40-13
Radiation
Evaporation
Convection
Conduction

27. Balancing Heat Loss and Gain
In thermoregulation, physiological and behavioral adjustments balance heat loss and gain
Five general adaptations help animals thermoregulate:
Insulation
Circulatory adaptations
Cooling by evaporative heat loss
Behavioral responses
Adjusting metabolic heat production

28. Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis
Adipose tissue
Blood vessels
Oil gland
Hair follicle

29. Circulatory Adaptations
In vasodilation, blood flow in the skin increases, facilitating heat loss
In vasoconstriction, blood flow in the skin decreases, lowering heat loss

31. Canada goose Pacific bottlenose dolphin Blood flow Artery Vein Vein
33°
30°
27°
20°
18°
10° 9°

32. LE 40-16a
21°
23°
25°
27°
29°
31°
Body cavity
Bluefin tuna

33. Skin Artery Vein Blood Capillary vessels network within in gills
LE 40-16b
Skin
Artery
Vein
Blood
vessels
in gills
Capillary
network within
muscle
Heart
Artery and
vein under
the skin
Dorsal aorta
Great white shark

35. Cooling by Evaporative Heat Loss
Many types of animals lose heat through evaporation of water in sweat
Panting augments the cooling effect in birds and many mammals
Bathing moistens the skin, helping to cool an animal down

38. Adjusting Metabolic Heat Production
Many species of flying insects use shivering to warm up before taking flight
PREFLIGHT
WARMUP
FLIGHT
Abdomen
Thorax
Time from onset of warmup (min) 4 2 40 35 30 25
Temperature (°C)

39. Feedback Mechanisms in Thermoregulation
Mammals regulate body temperature by negative feedback involving several organ systems
In humans, the hypothalamus (a part of the brain) contains nerve cells that function as a thermostat

40. Internal body temperature
LE 40-21
Thermostat in
hypothalamus
activates cooling
mechanisms.
Increased body
temperature (such
as when exercising
or in hot
surroundings)
Body temperature
decreases;
thermostat
shuts off cooling
Sweat glands secrete
sweat that evaporates,
cooling the body.
Blood vessels
in skin dilate:
capillaries fill
with warm blood;
heat radiates from
skin surface.
increases;
shuts off warming
Decreased body
temperature
(such as when
in cold
Blood vessels in skin
constrict, diverting blood
from skin to deeper tissues
and reducing heat loss
from skin surface.
Skeletal muscles rapidly
contract, causing shivering,
which generates heat.
activates
warming
Homeostasis:
Internal body temperature
of approximately 36–38°C

41. Adjustment to Changing Temperatures
In acclimatization, many animals adjust to a new range of environmental temperatures over a period of days or weeks

42. Torpor and Energy Conservation
Torpor is a physiological state in which activity is low and metabolism decreases
Torpor enables animals to save energy while avoiding difficult and dangerous conditions
Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity

43. LE 40-22 Additional metabolism that would be
necessary to stay active in winter
200
Actual
metabolism
Metabolic rate
(kcal per day)
100
Arousals 35
Body
temperature 30 25 20
Temperature (°C) 15 10 5 –5
Outside
temperature
Burrow
temperature
–10
–15
June
August
October
December
February
April

44. Estivation, or summer torpor, enables animals to survive long periods of high temperatures and scarce water supplies
Daily torpor is exhibited by many small mammals and birds and seems adapted to feeding patterns