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

2. Overview: Diverse Forms, Common Challenges
Animals inhabit almost every part of the biosphere
Despite their amazing diversity
All animals face a similar set of problems, including how to nourish themselves

3. The comparative study of animals
Reveals that form and function are closely correlated
Figure 40.1

4. Natural selection can fit structure, anatomy, to function, physiology
By selecting, over many generations, what works best among the available variations in a population

5. Physical laws and the need to exchange materials with the environment
Concept 40.1: Physical laws and the environment constrain animal size and shape
Physical laws and the need to exchange materials with the environment
Place certain limits on the range of animal forms

6. Physical Laws and Animal Form
The ability to perform certain actions
Depends on an animal’s shape and size

7. Evolutionary convergence
Reflects different species’ independent adaptation to a similar environmental challenge
(a) Tuna
(b) Shark
(c) Penguin
(d) Dolphin
Figure 40.2a–e
(e) Seal

8. Exchange with the Environment
An animal’s size and shape
Have a direct effect on how the animal exchanges energy and materials with its surroundings
Exchange with the environment occurs as substances dissolved in the aqueous medium
Diffuse and are transported across the cells’ plasma membranes

9. A single-celled protist living in water
Has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm
Diffusion
(a) Single cell
Figure 40.3a

10. Multicellular organisms with a sac body plan
Have body walls that are only two cells thick, facilitating diffusion of materials
Mouth
Gastrovascular
cavity
Diffusion
Diffusion
Figure 40.3b
(b) Two cell layers

11. Organisms with more complex body plans
Have highly folded internal surfaces specialized for exchanging materials

12. Figure 40.4 External environment Mouth Food CO2 O2 Animal body
Respiratory
system
Blood
50 µm
0.5 cm
Cells
A microscopic view of the lung reveals
that it is much more spongelike than
balloonlike. This construction provides
an expansive wet surface for gas
exchange with the environment (SEM).
Heart
Nutrients
Circulatory
system
10 µm
Interstitial
fluid
Digestive
system
The lining of the small intestine, a diges-
tive organ, is elaborated with fingerlike
projections that expand the surface area
for nutrient absorption (cross-section, SEM).
Excretory
system
Anus
Inside a kidney is a mass of microscopic
tubules that exhange chemicals with
blood flowing through a web of tiny
vessels called capillaries (SEM).
Unabsorbed
matter (feces)
Metabolic waste
products (urine)
Figure 40.4

13. Animals are composed of cells
Concept 40.2: Animal form and function are correlated at all levels of organization
Animals are composed of cells
Groups of cells with a common structure and function
Make up tissues
Different tissues make up organs
Which together make up organ systems

14. Tissue Structure and Function
Different types of tissues
Have different structures that are suited to their functions
Tissues are classified into four main categories
Epithelial, connective, muscle, and nervous

15. Epithelial Tissue Epithelial tissue
Covers the outside of the body and lines organs and cavities within the body
Contains cells that are closely joined

16. Stratified squamous epithelia Simple squamous epithelia
Epithelial tissue
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.
A simple
columnar
epithelium
A stratified columnar
epithelium
A pseudostratified
ciliated columnar
epithelium
Stratified squamous epithelia
Cuboidal epithelia
Simple squamous epithelia
Basement membrane
Figure 40.5
40 µm

17. Connective Tissue Connective tissue
Functions mainly to bind and support other tissues
Contains sparsely packed cells scattered throughout an extracellular matrix

18. Fibrous connective tissue
100 µm
Chondrocytes
Collagenous
fiber
Chondroitin
sulfate
Elastic
fiber
100 µm
Cartilage
Loose connective tissue
Adipose tissue
Fibrous connective tissue
Fat droplets
Nuclei
150 µm
30 µm
Bone
Blood
Central
canal
Red blood cells
White blood cell
Osteon
Plasma
Figure 40.5
700 µm
55 µm

19. Muscle Tissue Muscle tissue
Is composed of long cells called muscle fibers capable of contracting in response to nerve signals
Is divided in the vertebrate body into three types: skeletal, cardiac, and smooth

20. Nervous Tissue Nervous tissue
Senses stimuli and transmits signals throughout the animal

21. Muscle and nervous tissue
MUSCLE TISSUE
100 µm
Skeletal muscle
Multiple
nuclei
Muscle fiber
Sarcomere
Cardiac muscle
Nucleus
Intercalated
disk
50 µm
Smooth muscle
Nucleus
Muscle
fibers
25 µm
NERVOUS TISSUE
Neurons
Process
Cell body
Nucleus
Figure 40.5
50 µm

22. Organs and Organ Systems
In all but the simplest animals
Different tissues are organized into organs

23. In some organs The tissues are arranged in layers Figure 40.6 Lumen of
stomach
Mucosa. The mucosa is an
epithelial layer that lines
the lumen.
Submucosa. The submucosa is
a matrix of connective tissue
that contains blood vessels
and nerves.
Muscularis. The muscularis consists mainly of smooth muscle tissue.
0.2 mm
Serosa. External to the muscularis is the serosa, a thin layer of connective and epithelial tissue.
Figure 40.6

24. Representing a level of organization higher than organs
Organ systems carry out the major body functions of most animals

25. Organ systems in mammals
Table 40.1

26. All organisms require chemical energy for
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, and reproduction

27. The flow of energy through an animal, its bioenergetics
Ultimately limits the animal’s behavior, growth, and reproduction
Determines how much food it needs
Studying an animal’s bioenergetics
Tells us a great deal about the animal’s adaptations

28. Energy Sources and Allocation
Animals harvest chemical energy
From the food they eat
Once food has been digested, the energy-containing molecules
Are usually used to make ATP, which powers cellular work

29. After the energetic needs of staying alive are met
Any remaining molecules from food can be used in biosynthesis
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
Figure 40.7
Heat

30. Quantifying Energy Use
An animal’s metabolic rate
Is the amount of energy an animal uses in a unit of time
Can be measured in a variety of ways

31. One way to measure metabolic rate
Is to determine the amount of oxygen consumed or carbon dioxide produced by an organism
Figure 40.8a, b
This photograph shows a ghost crab in a respirometer. Temperature is held constant in the chamber, with air of known O2 concentration flow- ing 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.
(a)
(b) Similarly, the metabolic rate of a man fitted with a breathing apparatus is being monitored while he works out on a stationary bike.

32. Bioenergetic Strategies
An animal’s metabolic rate
Is closely related to its bioenergetic strategy

33. Birds and mammals are mainly endothermic, meaning that
Their bodies are warmed mostly by heat generated by metabolism
They typically have higher metabolic rates

34. Amphibians and reptiles other than birds are ectothermic, meaning that
Stem Elongation
Amphibians and reptiles other than birds are ectothermic, meaning that
They gain their heat mostly from external sources
They have lower metabolic rates

35. Influences on Metabolic Rate
The metabolic rates of animals
Are affected by many factors

36. Size and Metabolic Rate
Metabolic rate per gram
Is inversely related to body size among similar animals

37. 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
For both endotherms and ectotherms
Activity has a large effect on metabolic rate

38. In general, an animal’s maximum possible metabolic rate
Is inversely related to the duration of the activity
Maximum metabolic rate
(kcal/min; log scale)
500
100 50 10 5 1
0.5
0.1 A H
A = 60-kg alligator
H = 60-kg human
second
minute
hour
Time interval
day
week
Key
Existing intracellular ATP
ATP from glycolysis
ATP from aerobic respiration
Figure 40.9

39. Different species of animals
Energy Budgets
Different species of animals
Use the energy and materials in food in different ways, depending on their environment

40. Energy expenditures per unit mass (kcal/kg•day)
An animal’s use of energy
Is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction
Endotherms
Ectotherm
Annual energy expenditure (kcal/yr)
800,000
Basal
metabolic
rate
Reproduction
Temperature
regulation costs
Growth
Activity
costs
60-kg female human
from temperate climate
Total annual energy expenditures
(a)
340,000
4-kg male Adélie penguin
from Antarctica (brooding)
4,000
0.025-kg female deer mouse
from temperate
North America
8,000
4-kg female python
from Australia
Energy expenditure per unit mass
(kcal/kg•day)
438
Deer mouse
233
Adélie penguin
36.5
Human
5.5
Python
Energy expenditures per unit mass (kcal/kg•day)
(b)
Figure 40.10a, b

41. The internal environment of vertebrates
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

42. Regulating and Conforming
Are two extremes in how animals cope with environmental fluctuations

43. An animal is said to be a regulator
If it uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation
An animal is said to be a conformer
If it allows its internal condition to vary with certain external changes

44. Mechanisms of Homeostasis
Moderate changes in the internal environment

45. A homeostatic control system has three functional components
A receptor, a control center, and an effector
Response
No heat
produced
Room
temperature
decreases
Heater
turned
off
Set point
Too
hot
Set
point
Control center:
thermostat
increases on
cold
Heat
Figure 40.11

46. Most homeostatic control systems function by negative feedback
Where buildup of the end product of the system shuts the system off

47. A second type of homeostatic control system is positive feedback
Which involves a change in some variable that triggers mechanisms that amplify the change

48. 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

49. Ectotherms and Endotherms
Include most invertebrates, fishes, amphibians, and non-bird reptiles
Endotherms
Include birds and mammals

50. In general, ectotherms
Tolerate greater variation in internal temperature than endotherms
River otter (endotherm)
Largemouth bass (ectotherm)
Ambient (environmental) temperature (°C)
Body temperature (°C) 40 30 20 10
Figure 40.12

51. Endothermy is more energetically expensive than ectothermy
But buffers animals’ internal temperatures against external fluctuations
And enables the animals to maintain a high level of aerobic metabolism

52. Organisms exchange heat by four physical processes
Modes of Heat Exchange
Organisms exchange heat by four physical processes
Radiation is the emission of electromagnetic
waves by all objects warmer than absolute
zero. Radiation can transfer heat between
objects that are not in direct contact, as when
a lizard absorbs heat radiating from the sun.
Evaporation is the removal of heat from the surface of a
liquid that is losing some of its molecules as gas.
Evaporation of water from a lizard’s moist surfaces that
are exposed to the environment has a strong cooling effect.
Convection is the transfer of heat by the
movement of air or liquid past a surface,
as when a breeze contributes to heat loss
from a lizard’s dry skin, or blood moves
heat from the body core to the extremities.
Conduction is the direct transfer of thermal motion (heat)
between molecules of objects in direct contact with each
other, as when a lizard sits on a hot rock.
Figure 40.13

53. Balancing Heat Loss and Gain
Thermoregulation involves physiological and behavioral adjustments
That balance heat gain and loss

54. Insulation
Insulation, which is a major thermoregulatory adaptation in mammals and birds
Reduces the flow of heat between an animal and its environment
May include feathers, fur, or blubber

55. In mammals, the integumentary system
Acts as insulating material
Hair
Epidermis
Sweat
pore
Muscle
Dermis
Nerve
Sweat
gland
Hypodermis
Adipose tissue
Blood vessels
Oil gland
Figure 40.14
Hair follicle

56. Circulatory Adaptations
Many endotherms and some ectotherms
Can alter the amount of blood flowing between the body core and the skin

57. In vasodilation In vasoconstriction
Blood flow in the skin increases, facilitating heat loss
In vasoconstriction
Blood flow in the skin decreases, lowering heat loss

58. Many marine mammals and birds
Have arrangements of blood vessels called countercurrent heat exchangers that are important for reducing heat loss
In the flippers of a dolphin, each artery is
surrounded by several veins in a
countercurrent arrangement, allowing
efficient heat exchange between arterial
and venous blood.
Canada
goose
Artery
Vein
35°C
Blood flow
30º
20º
10º
33°
27º
18º 9º
Pacific
bottlenose
dolphin 2 1 3
Arteries carrying warm blood down the
legs of a goose or the flippers of a dolphin
are in close contact with veins conveying
cool blood in the opposite direction, back
toward the trunk of the body. This
arrangement facilitates heat transfer
from arteries to veins (black
arrows) along the entire length
of the blood vessels.
Near the end of the leg or flipper, where
arterial blood has been cooled to far below
the animal’s core temperature, the artery
can still transfer heat to the even colder
blood of an adjacent vein. The venous blood
continues to absorb heat as it passes warmer
and warmer arterial blood traveling in the
opposite direction.
As the venous blood approaches the
center of the body, it is almost as warm
as the body core, minimizing the heat lost
as a result of supplying blood to body parts
immersed in cold water. 1 3
Figure 40.15

59. Some specialized bony fishes and sharks
Also possess countercurrent heat exchangers
21º
25º
23º
27º
29º
31º
Body cavity
Skin
Artery
Vein
Capillary
network within
muscle
Dorsal aorta
Artery and
vein under
the skin
Heart
Blood
vessels
in gills
(a) Bluefin tuna. Unlike most fishes, the bluefin tuna maintains
temperatures in its main swimming muscles that are much higher
than the surrounding water (colors indicate swimming muscles cut
in transverse section). These temperatures were recorded for a tuna
in 19°C water.
(b) Great white shark. Like the bluefin tuna, the great white shark
has a countercurrent heat exchanger in its swimming muscles that
reduces the loss of metabolic heat. All bony fishes and sharks lose
heat to the surrounding water when their blood passes through the
gills. However, endothermic sharks have a small dorsal aorta,
and as a result, relatively little cold blood from the gills goes directly
to the core of the body. Instead, most of the blood leaving the gills
is conveyed via large arteries just under the skin, keeping cool blood
away from the body core. As shown in the enlargement, small
arteries carrying cool blood inward from the large arteries under the
skin are paralleled by small veins carrying warm blood outward from
the inner body. This countercurrent flow retains heat in the muscles.
Figure 40.16a, b

60. Many endothermic insects
Have countercurrent heat exchangers that help maintain a high temperature in the thorax
Figure 40.17

61. Cooling by Evaporative Heat Loss
Many types of animals
Lose heat through the evaporation of water in sweat
Use panting to cool their bodies

62. Bathing moistens the skin
Which helps to cool an animal down
Figure 40.18

63. Both endotherms and ectotherms
Behavioral Responses
Both endotherms and ectotherms
Use a variety of behavioral responses to control body temperature

64. Some terrestrial invertebrates
Have certain postures that enable them to minimize or maximize their absorption of heat from the sun
Figure 40.19

65. Adjusting Metabolic Heat Production
Some animals can regulate body temperature
By adjusting their rate of metabolic heat production

66. Time from onset of warmup (min)
Many species of flying insects
Use shivering to warm up before taking flight
PREFLIGHT
WARMUP
FLIGHT
Thorax
Abdomen
Temperature (°C)
Time from onset of warmup (min) 40 35 30 25 2 4
Figure 40.20

67. Feedback Mechanisms in Thermoregulation
Mammals regulate their body temperature
By a complex negative feedback system that involves several organ systems

68. Internal body temperature
In humans, a specific part of the brain, the hypothalamus
Contains a group of nerve cells that function as a thermostat
Thermostat in
hypothalamus
activates cooling
mechanisms.
Sweat glands secrete
sweat that evaporates,
cooling the body.
Blood vessels
in skin dilate:
capillaries fill
with warm blood;
heat radiates from
skin surface.
Body temperature
decreases;
thermostat
shuts off cooling
Increased body
temperature (such
as when exercising
or in hot
surroundings)
Homeostasis:
Internal body temperature
of approximately 36–38C
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
Figure 40.21

69. Adjustment to Changing Temperatures
In a process known as acclimatization
Many animals can adjust to a new range of environmental temperatures over a period of days or weeks

70. Acclimatization may involve cellular adjustments
Or in the case of birds and mammals, adjustments of insulation and metabolic heat production

71. Torpor and Energy Conservation
Is an adaptation that enables animals to save energy while avoiding difficult and dangerous conditions
Is a physiological state in which activity is low and metabolism decreases

72. Hibernation is long-term torpor
That is an adaptation to winter cold and food scarcity during which the animal’s body temperature declines
Additional metabolism that would be
necessary to stay active in winter
200
Actual
metabolism
100
Figure 40.22
Metabolic rate
(kcal per day)
Arousals 35
Body
temperature 30 25 20
Temperature (°C) 15 10 5
Outside
temperature -5
Burrow
temperature
-10
-15
June
August
October
December
February
April

73. 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 to be adapted to their feeding patterns