1. Animal Structure and Function: An Introduction
Chapter 38

2. KEY CONCEPTS
Structure and function are closely linked at every level of organization

3. Learning Objective 1
Compare the structure and function of the four main kinds of animal tissues: epithelial, connective, muscle, and nervous

4. Tissue A group of similarly specialized cells
Associated to perform one or more functions

5. Epithelial Tissue (Epithelium)
A continuous layer (sheet) of cells
covering a body surface
lining a body cavity
Functions in protection, absorption, secretion, or sensation

6. Connective Tissue 1
Relatively few cells separated by intercellular substance
fibers scattered throughout a matrix
Intercellular substance fibers
collagen fibers
elastic fibers
reticular fibers

7. Connective Tissue 2 Contains specialized cells Functions:
such as fibroblasts and macrophages
Functions:
joins other body tissues
supports body and organs
protects underlying organs

8. Muscle Tissue Consists of cells specialized to contract
Each cell is an elongated muscle fiber
many contractile units (myofibrils)

9. Nervous Tissue Neurons Glial cells elongated cells
specialized for transmitting impulses
Glial cells
support and nourish neurons

10. Learning Objective 2
Compare the structure and function of the main types of epithelial tissue

11. Epithelial Tissue Epithelial cell shapes Epithelial tissue structure
squamous, cuboidal, columnar
Epithelial tissue structure
simple, stratified, pseudostratified
(See Table 38-1)

12. Simple Squamous Epithelium
Lines blood vessels and air sacs in lungs
Permits exchange of materials by diffusion

13. Simple Cuboidal and Columnar Epithelia
Line passageways
Specialized for secretion and absorption

14. Stratified Squamous Epithelium
Forms outer layer of skin
Lines passageways into the body
Provides protection

15. Pseudostratified Epithelium
Lines passageways
Protects underlying tissues

16. Glands 1 Specialized epithelial tissue Goblet cells
unicellular exocrine glands that secrete mucus

17. Glands 2 Exocrine glands Endocrine glands
secrete product through a duct onto exposed epithelial surface
Endocrine glands
release hormones into interstitial fluid or blood

18. Glands

19. Unicellular glands (goblet cells) Cilia
Basement membrane
(a) Goblet cells.
Skin
Figure 38.1: Glands.
A gland consists of one or more epithelial cells.
(b) Sweat gland.
(c) Parotid salivary gland.
Fig. 38-1, p. 809

20. Membranes Epithelial membrane Mucous membrane Serous membrane
sheet of epithelial tissue
layer of underlying connective tissue
Mucous membrane
lines cavity that opens to outside of body
Serous membrane
lines cavity that does not open to the outside

21. Learning Objective 3 Compare the main types of connective tissue
Summarize their functions

22. Connective Tissues Cells embedded in intercellular substance
microscopic collagen fibers, elastic fibers, reticular fibers (thin branched fibers)
scattered through a matrix (thin gel of polysaccharides)

23. Loose Connective Tissue
Consists of fibers running in various directions through a semifluid matrix
Flexible tissue forms a covering for nerves, blood vessels, and muscles

24. Dense Connective Tissue
Stronger, less flexible than loose connective tissue
Collagen fibers arranged in definite pattern
Forms
tendons (connect muscles to bones)
ligaments (connect bones to bones)

25. Dense Connective Tissue

26. Elastic Connective Tissue
Consists of bundles of parallel elastic fibers
Found in lung tissue, walls of large arteries

27. Reticular Connective Tissue
Consists of interlacing reticular fibers
Forms support framework for many organs

28. Adipose Tissue Consists of fat cells
Found with loose connective tissue in subcutaneous tissue

29. Cartilage and Bone Form skeletons of vertebrates
Cartilage consists of chondrocytes
in lacunae (small cavities in hard matrix)
nonvascular
Osteocytes
secrete and maintain bone matrix
vascular

30. Cartilage and Bone
Cartilage
Bone

31. Bone

32. (a) The human skeleton consists mainly of bone.
Figure 38.2: Bone.
(a) The human skeleton consists mainly of bone.
(b) A bone is cut open, exposing its internal structure.
Fig. 38-2ab, p. 814

33. Blood and Lymph Circulating tissues
fluid intercellular substances
Help parts of an animal communicate with one another

34. Learning Objective 4
Contrast the three types of muscle tissue and their functions

35. Skeletal Muscle Striated and under voluntary control
Elongated, cylindrical fibers with several nuclei
Skeletal muscles contract, move parts of the body

36. Cardiac Muscle Striated, contractions are involuntary
Elongated, cylindrical fibers branch and fuse; one or two central nuclei
Muscle contracts, heart pumps blood

37. Smooth Muscle No striations, contractions involuntary
Elongated, spindle-shaped fibers with a single central nucleus
Smooth muscle moves body organs (example: pushes food through digestive tract)

38. Muscle Tissues

39. Learning Objective 5
How does the structure of the neuron relate to its function?

40. Neuron Elongated cell Receives and transmits information Synapse
a junction between neurons

41. Neuron Dendrites Axon receive signals transmit signals to cell body
transmits signals away from cell body
to other neurons, muscles, glands

42. Neuron

43. Neurons Dendrite Nuclei of glial cells Axon 100 µm Fig. 38-3, p. 817
Figure 38.3: LM of nervous tissue.
Neurons transmit impulses. Glial cells support and nourish neurons.
Axon
100 µm
Fig. 38-3, p. 817

44. KEY CONCEPTS
The main types of tissues in a complex animal are epithelial, connective, muscle, and nervous

45. Learning Objective 6 Describe the organ systems of a mammal
Summarize the homeostatic actions of each organ system

46. Organ Systems Tissues and organs working together
In mammals, 11 organ systems work together in the organism
Each organ system functions to maintain homeostasis

47. 11 Organ Systems Integumentary Respiratory Skeletal Urinary
Muscular Nervous
Digestive Endocrine
Cardiovascular Reproductive
Immune (lymphatic)

48. 11 Organ Systems

49. 11 Organ Systems

50. Insert “Human organ systems”
organ_systems_v2.swf

51. Watch body systems work together by clicking on the figure in ThomsonNOW.

52. KEY CONCEPTS
Tissues and organs form the 11 main organ systems of a complex animal

53. Learning Objective 7 Define homeostasis
Contrast negative and positive feedback systems

54. Homeostasis Balanced internal environment (steady state)
Homeostatic mechanisms
control processes that maintain conditions

55. Negative Feedback Systems 1
Maintain dynamic equilibrium (homeostasis)
1. Stressor
causes change in some steady state
2. Triggers a response
that opposes the change

56. Negative Feedback Systems 2
3. Sensor detects change
a deviation from desired condition (set point)
4. Sensor signals an integrator (control center)
5. Integrator activates effectors
organs or processes that restore steady state

57. Negative Feedback

58. Normal condition (set point) restored.
Stressor
HOMEOSTASIS 5
Normal condition (set point) restored. 1
Stressor causes deviation from set point. 4
Integrator activates effectors (homeostatic mechanisms).
Figure 38.5: Negative feedback. 2
Sensor detects change from set point. 3
Sensor signals integrator
(control center).
Fig. 38-5, p. 821

59. Positive Feedback System
Deviation from steady state causes changes that intensify (rather than reverse) the changes

60. Positive Feedback

61. Loss of blood causes blood pressure to decrease.
Stressor: hemorrhage
Homeostasis 1
Loss of blood causes blood pressure to decrease. 4
Cardiac output decreases (heart pumps less blood).
Figure 38.7: Positive feedback.
In positive feedback, the changes that occur amplify the deviation from the set point. Loss of blood causes blood pressure to decrease. Less blood reaches the heart, so heart function decreases. The resulting decrease in cardiac output further decreases blood pressure, bringing about conditions farther from homeostasis. 2
Less blood circulates
to heart. 3
Heart function declines.
Fig. 38-7, p. 822

62. KEY CONCEPTS
Homeostatic mechanisms are responsible for the body’s automatic tendency to maintain a relatively stable internal environment

63. Learning Objective 8
Compare the costs and benefits of ectothermy

64. Thermoregulation
Process of maintaining body temperature within certain limits
despite changes in surrounding temperature
Animals have different structural, behavioral, and physiological strategies

65. Ectotherms
In ectotherms, body temperature depends on temperature of environment
Use behavioral strategies to adjust body temperatures

66. Costs and Benefits Benefits of ectothermy Disadvantage of ectothermy
very little energy used to maintain the metabolic rate
ectotherms can survive on less food
Disadvantage of ectothermy
activity limited by daily and seasonal temperature conditions

67. Learning Objective 9 Compare the costs and benefits of endothermy
Describe strategies animals use to adjust to challenging temperature changes

68. Endotherms Have homeostatic mechanisms
regulate body temperature within a narrow range

69. Costs and Benefits Benefits of endothermy Disadvantage of endothermy
high metabolic rate
constant body temperature allows higher rate of enzyme activity
active even in low winter temperatures
Disadvantage of endothermy
high energy cost

70. Temperature Regulation in Humans

71. HOMEOSTASIS Decreased muscle activity Increased sweating/ panting
Nerves
Evaporation
Smooth muscle in blood vessels relaxes
Blood vessels dilate
Sensors signal temperature- regulating center in hypothalamus (integrator)
Specialized nerve cells (sensors) detect change from set point
Figure 38.9: Regulation of temperature in the human body.
Body temperature increases
Body temperature decreases (normal condition restored)
Stressors
Stressors
HOMEOSTASIS
Fig. 38-9, p. 823

72. Body temperature increases (normal condition restored)
Body temperature decreases
Specialized nerve cells (sensors) detect change from set point
Sensors signal temperature- regulating center in hypothalamus (integrator)
Increase in voluntary movement; shivering
Blood vessels constrict
Figure 38.9: Regulation of temperature in the human body.
Nerves
Smooth muscle in blood vessels contracts
Increase in metabolic rate
Anterior pituitary gland
Thyroid gland
Fig. 38-9, p. 823

73. Insert “Control of human body temperature”
hot_guy_m.swf

74. Acclimatization
Process of adjustment to seasonal changes

75. Torpor Torpor Hibernation Estivation
adaptive hypothermia (in small endotherms when surrounding temperature drops)
Hibernation
long-term torpor in response to winter cold
Estivation
torpor due to lack of food or water during summer heat

76. KEY CONCEPTS
Thermoregulation contributes to homeostasis

77. Insert “Human thermoregulation”
temp_regulation.swf

78. Explore negative feedback and temperature regulation in humans and other animals by clicking on the figures in ThomsonNOW.