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

2. Anatomy is the study of the biological form of an organism
1. Distinguish between anatomy and physiology. Give some examples of how the jackrabbit’s anatomy and physiology allow it to survive in its environment.
Anatomy is the study of the biological form of an organism
Physiology is the study of the biological functions an organism performs
The comparative study of animals reveals that form and function are closely correlated
The rabbit’s big ears (anatomy) function to help the rabbit regulate its body temperature (physiology).
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3. Hierarchical Organization of Body Plans
Most animals are composed of specialized cells organized into tissues that have different functions
Tissues make up organs, which together make up organ systems
In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells
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4. 2. Know the 11 main organ systems in mammals.
Table 40-1
2. Know the 11 main organ systems in mammals.

5. 3. List and briefly describe the four main types of animal tissues
3. List and briefly describe the four main types of animal tissues. Epithelial Tissue
Epithelial tissue covers the outside of the body and lines the organs and cavities within the body
It contains cells that are closely joined
The shape of epithelial cells may be cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles)
polarized – meaning they have two different sides.
often covered with small projections, i.e. microvilli, that increase surface area
often have active interfaces with the environment, ie nasal passages
simple, stratified, or pseudostratified
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6. Epithelial Tissue Cuboidal epithelium Simple columnar epithelium
Fig. 40-5a
Epithelial Tissue
Cuboidal
epithelium
Simple
columnar
epithelium
Pseudostratified
ciliated
columnar
epithelium
Stratified
squamous
epithelium
Figure 40.5 Structure and function in animal tissues
Simple
squamous
epithelium

8. Connective tissue mainly binds and supports other tissues
It contains sparsely packed cells scattered throughout an extracellular matrix
The matrix consists of fibers in a liquid, jellylike, or solid foundation
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9. Cartilage is a strong and flexible support material
In vertebrates, the fibers and foundation combine to form six major types of connective tissue:
Loose connective tissue binds epithelia to underlying tissues and holds organs in place
Cartilage is a strong and flexible support material
Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints
Adipose tissue stores fat for insulation and fuel
Blood is composed of blood cells and cell fragments in blood plasma
Bone is mineralized and forms the skeleton
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10. Connective Tissue Loose connective tissue Cartilage Fibrous connective
Fig. 40-5c
Connective Tissue
Collagenous fiber
Loose
connective
tissue
Chondrocytes
Cartilage
120 µm
100 µm
Elastic fiber
Chondroitin
sulfate
Nuclei
Fat droplets
Fibrous
connective
tissue
Adipose
tissue
30 µm
150 µm
Figure 40.5 Structure and function in animal tissues
Osteon
White blood cells
Bone
Blood
700 µm
55 µm
Central canal
Plasma
Red blood
cells

11. It is divided in the vertebrate body into three types:
Muscle Tissue
Muscle tissue consists of long cells called muscle fibers, which contract in response to nerve signals
It is divided in the vertebrate body into three types:
Skeletal muscle, or striated muscle, is responsible for voluntary movement
Smooth muscle is responsible for involuntary body activities
Cardiac muscle is responsible for contraction of the heart
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12. Muscle Tissue Skeletal muscle Cardiac muscle Smooth muscle Multiple
Fig. 40-5j
Muscle Tissue
Multiple
nuclei
Muscle fiber
Sarcomere
Skeletal
muscle
Nucleus
100 µm
Intercalated
disk
50 µm
Cardiac muscle
Smooth
muscle
Nucleus
Figure 40.5 Structure and function in animal tissues
Muscle
fibers
25 µm

13. Nervous tissue contains:
Nervous tissue senses stimuli and transmits signals throughout the animal
Nervous tissue contains:
Neurons, or nerve cells, that transmit nerve impulses
Glial cells, or glia, that help nourish, insulate, and replenish neurons
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14. Nervous Tissue Neuron 40 µm Axons Blood vessel Dendrites Cell body
Fig. 40-5n
Nervous Tissue
40 µm
Dendrites
Cell body
Axon
Glial cells
Neuron
Figure 40.5 Structure and function in animal tissues
Axons
Blood vessel
15 µm

15. Coordination and Control
Control and coordination within a body depend on the endocrine system and the nervous system
The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood
The endocrine system causes gradual changes, i.e. growth and development;
The nervous system directs immediate and rapid responses to the environment.
Both contribute to maintaining a stable internal environment.
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16. (a) Signaling by hormones (b) Signaling by neurons
Fig. 40-6
Stimulus
Stimulus
Endocrine
cell
Neuron
Axon
Signal
Hormone
Signal travels
along axon to
a specific
location.
Signal travels
everywhere
via the
bloodstream.
Blood
vessel
Signal
Axons
Figure 40.6 Signaling in the endocrine and nervous systems
Response
Response
(a) Signaling by hormones
(b) Signaling by neurons

17. 4. What is the difference between regulating and conforming
4. What is the difference between regulating and conforming? Give an example of each.
A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation
A conformer allows its internal condition to vary with certain external changes
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18. (temperature conformer)
Fig. 40-7 40
River otter (temperature regulator) 30
Body temperature (°C) 20
Largemouth bass
(temperature conformer) 10
Figure 40.7 The relationship between body and environmental temperatures in an aquatic temperature regulator and an aquatic temperature conformer 10 20 30 40
Ambient (environmental) temperature (ºC)

19. 5. What is homeostasis? Describe the mechanisms of homeostasis.
Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment
In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level
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20. Mechanisms of Homeostasis
Mechanisms of homeostasis moderate changes in the internal environment
For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response
The response returns the variable to the set point
Animation: Negative Feedback
Animation: Positive Feedback
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21. Response: Heater turned off Room temperature decreases Stimulus:
Fig. 40-8
Response:
Heater
turned
off
Room
temperature
decreases
Stimulus:
Control center
(thermostat)
reads too hot
Set
point:
20ºC
Figure 40.8 A nonliving example of negative feedback: control of room temperature
Stimulus:
Control center
(thermostat)
reads too cold
Room
temperature
increases
Response:
Heater
turned on

22. 6. Distinguish between negative feedback and positive feedback.
The dynamic equilibrium of homeostasis is maintained by negative feedback, which helps to return a variable to either a normal range or a set point
Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off
Positive feedback loops occur in animals, but do not usually contribute to homeostasis. i.e. contractions during childbirth, lactation.
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23. 7. What is acclimatization?
Set points and normal ranges can change with age or show cyclic variation
Homeostasis can adjust to changes in external environment, a process called acclimatization
Ex: Elk moving from sea level to higher elevation.
These are temporary changes, not adaptations.
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24. Concept 40.3: Homeostatic processes for thermoregulation involve form, function, and behavior
Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range
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25. Endothermy and Ectothermy
Endothermic animals generate heat by metabolism; birds and mammals are endotherms
Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and non-avian reptiles
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26. (a) A walrus, an endotherm
Fig. 40-9
(a) A walrus, an endotherm
Figure 40.9 Endothermy and ectothermy
(b) A lizard, an ectotherm

27. Variation in Body Temperature
The body temperature of a poikilotherm varies with its environment, while that of a homeotherm is relatively constant
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28. Five general adaptations help animals thermoregulate:
Insulation
Circulatory adaptations
Cooling by evaporative heat loss
Behavioral responses
Adjusting metabolic heat production
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29. Insulation is a major thermoregulatory adaptation in mammals and birds
Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment
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30. Circulatory Adaptations
Regulation of blood flow near the body surface significantly affects thermoregulation
Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin
In vasodilation, blood flow in the skin increases, facilitating heat loss
In vasoconstriction, blood flow in the skin decreases, lowering heat loss
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31. The arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange
Countercurrent heat exchangers transfer heat between fluids flowing in opposite directions
Countercurrent heat exchangers are an important mechanism for reducing heat loss
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32. Canada goose Bottlenose dolphin Blood flow Artery Vein Vein Artery
Fig
Canada goose
Bottlenose
dolphin
Blood flow
Artery
Vein
Vein
Artery
35ºC
33º
30º
27º
Figure Countercurrent heat exchangers
20º
18º
10º 9º

33. Cooling by Evaporative Heat Loss
Many types of animals lose heat through evaporation of water in sweat
Panting increases the cooling effect in birds and many mammals
Sweating or bathing moistens the skin, helping to cool an animal down
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34. Behavioral Responses
Both endotherms and ectotherms use behavioral responses to control body temperature
Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat
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35. Fig
Figure Thermoregulatory behavior in a dragonfly

36. Acclimatization in Thermoregulation
Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes
When temperatures are subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells
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37. Physiological Thermostats and Fever
Thermoregulation is controlled by a region of the brain called the hypothalamus
The hypothalamus triggers heat loss or heat generating mechanisms
Fever is the result of a change to the set point for a biological thermostat
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38. Sweat glands secrete sweat, which evaporates, cooling the body.
Fig
Sweat glands secrete sweat, which evaporates, cooling the body.
Thermostat in hypothalamus activates cooling mechanisms.
Blood vessels in skin dilate: capillaries fill; heat radiates from skin.
Body temperature decreases; thermostat shuts off cooling mechanisms.
Increased body temperature
Homeostasis: Internal temperature of 36–38°C
Body temperature increases; thermostat shuts off warming mechanisms.
Decreased body temperature
Figure The thermostatic function of the hypothalamus in human thermoregulation
Blood vessels in skin constrict, reducing heat loss.
Thermostat in hypothalamus activates warming mechanisms.
Skeletal muscles contract; shivering generates heat.

39. 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
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40. Fig
Figure Measuring rate of oxygen consumption in a running pronghorn

41. Minimum Metabolic Rate and Thermoregulation
Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature
Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature
Both rates assume a nongrowing, fasting, and nonstressed animal
Ectotherms have much lower metabolic rates than endotherms of a comparable size
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42. Size and Metabolic Rate
Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectotherm
Two of these factors are size and activity
Metabolic rate per gram is inversely related to body size among similar animals
Researchers continue to search for the causes of this relationship
The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal
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43. Figure 40.19 The relationship of metabolic rate to body size
103
Elephant
102
Horse
Human 10
Sheep
BMR (L O2/hr) (Iog scale)
Cat
Dog 1
Rat
10–1
Ground squirrel
Shrew
Mouse
Harvest mouse
10–2
10–3
10–2
10–1 1 10
102
103
Body mass (kg) (log scale)
(a) Relationship of BMR to body size 8
Shrew 7 6
Figure The relationship of metabolic rate to body size 5
BMR (L O2/hr) (per kg) 4 3
Harvest mouse 2
Mouse
Sheep
Rat
Human
Elephant 1
Cat
Dog
Ground squirrel
Horse
10–3
10–2
10–1 1 10
102
103
Body mass (kg) (log scale)
(b) Relationship of BMR per kilogram of body mass to body size

44. 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
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45. Fig. 40-UN2

46. You should now be able to:
Distinguish among the following sets of terms: collagenous, elastic, and reticular fibers; regulator and conformer; positive and negative feedback; basal and standard metabolic rates; torpor, hibernation, estivation, and daily torpor
Relate structure with function and identify diagrams of the following animal tissues: epithelial, connective tissue (six types), muscle tissue (three types), and nervous tissue
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47. Compare and contrast the nervous and endocrine systems
Define thermoregulation and explain how endotherms and ectotherms manage their heat budgets
Describe how a countercurrent heat exchanger may function to retain heat within an animal body
Define bioenergetics and biosynthesis
Define metabolic rate and explain how it can be determined for animals
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