CHAPTER 40 Physiology, Homeostasis, and Temperature Regulation

1. CHAPTER 40Physiology, Homeostasis, and Temperature Regulation

2. Chapter 40: Physiology, Homeostasis, and Temperature Regulation Homeostasis: Maintaining the Internal Environment Tissues, Organs, and Organ Systems Physiological Regulation and Homeostasis

3. Chapter 40: Physiology, Homeostasis, and Temperature Regulation Temperature and Life Maintaining Optimal Body Temperature Thermoregulation in Endotherms The Vertebrate Thermostat

4. Homeostasis: Maintaining the Internal Environment • Single-celled organisms and some small, simple multicellular animals meet their needs by direct exchange between their cells and an aqueous environment. • Larger, more complex animals must do so by maintaining a constant internal environment. 4

5. Homeostasis: Maintaining the Internal Environment • The internal environment consists of the extracellular fluids. • Organs and organ systems have specialized functions to keep certain aspects of the internal environment in a constant state. Review Figure 40.1 5

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7. Homeostasis: Maintaining the Internal Environment • Homeostasis is the maintenance of constancy in the internal environment • It depends on the ability to control and regulate organ and organ system function. 7

8. Tissues, Organs and Organ Systems • Cells with a similar structure and function make up a tissue. • There are four general types: • Epithelial • Connective • Muscle • Nervous. Review Figure 40.2 8

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10. Tissues, Organs, and Organ Systems • Epithelial tissues are sheets of tightly connected cells that cover body surfaces and line hollow organs. 10

11. Tissues, Organs, and Organ Systems • Connective tissues support and reinforce other tissues. • They generally consist of dispersed cells in an extracellular matrix. 11

12. Tissues, Organs, and Organ Systems • Muscle tissues contract. • There are three types: • Skeletal • Cardiac • Smooth. 12

13. Tissues, Organs, and Organ Systems • There are two types of nerve cells: • Neurons generate and transmit electrochemical signals • Glial cells provide supporting functions for neurons. 13

14. Tissues, Organs, and Organ Systems • Organs consist of multiple tissue types, and organs make up organ systems. Review Table 40.1 14

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16. table 40-01b.jpg Table 40.1 – Part 2 Table 40.1 – Part 2

17. Physiological Regulation and Homeostasis • Regulatory systems have set points and respond to feedback information. • Negative feedback corrects deviations from the set point • Positive feedback amplifies responses • Feedforward information changes the set point. Review Figure 40.5 17

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19. Temperature and Life • Living systems require a range of temperatures between the freezing point of water and the temperatures that denature proteins. 19

20. Temperature and Life • Most biological processes and reactions are temperature-sensitive. • Q10 is a measure of temperature sensitivity. Review Figure 40.6 20

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22. Temperature and Life • Animals that cannot avoid seasonal changes in body temperature have biochemical adaptations to compensate. • These enable animals to acclimatize to seasonal changes. Review Figure 40.7 22

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24. Maintaining Optimal Body Temperature • Homeotherms maintain a fairly constant body temperature most of the time; poikilotherms do not. • Endotherms produce metabolic heat; ectotherms depend mostly on environmental sources of heat. Review Figure 40.8 24

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26. Maintaining Optimal Body Temperature • Ectotherms and endotherms can regulate body temperature through behavior. Review Figure 40.9 26

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28. Maintaining Optimal Body Temperature • Heat exchange between a body and the environment is via: • radiation • conduction • convection • Evaporation Review Figure 40.11 28

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30. Maintaining Optimal Body Temperature • Ectotherms and endotherms can control heat exchange with the environment by altering blood flow to the skin. Review Figure 40.12 30

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32. Maintaining Optimal Body Temperature • Some ectotherms can produce metabolic heat to raise their body temperatures. Review Figure 40.13 32

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34. Maintaining Optimal Body Temperature • Some fish have circulatory systems that function as countercurrent heat exchangers to conserve heat produced by muscle metabolism. Review Figure 40.14 34

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36. figure 40-14b.jpg Figure 40.14 – Part 2 Figure 40.14 – Part 2

37. Thermoregulation in Endotherms • Endotherms have high basal metabolic rates. • Over a range of environmental temperatures, the thermoneutral zone, their resting metabolic rates remain at basal levels. Review Figure 40.15 37

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39. Thermoregulation in Endotherms • When environmental temperature falls below a lower critical temperature, endotherms maintain their body temperatures through shivering and nonshivering metabolic heat production. 39

40. Thermoregulation in Endotherms • When environmental temperature rises above an upper critical temperature, metabolic rate increases as a consequence of evaporative water loss. 40

41. Thermoregulation in Endotherms • Endotherms in cold climates have adaptations that minimize heat loss: • a reduced surface area-to-volume ratio • increased insulation. 41

42. Thermoregulation in Endotherms • Endotherms may dissipate excess heat generated by exercise or the environment via evaporation. • However, water loss can be dangerous to endotherms in dry environments. 42

43. The Vertebrate Thermostat • The vertebrate thermostat is in the hypothalamus. • It has set points for activating thermoregulatory responses. • Hypothalamic temperature provides negative feedback information. 43

44. The Vertebrate Thermostat • Cooling the hypothalamus induces blood vessel constriction and increased metabolic heat production • Heating it induces blood vessel dilation and active evaporative water loss. • Thermoregulatory behaviors are induced by changes in hypothalamic temperature. Review Figure 40.18 44

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46. The Vertebrate Thermostat • Changes in set point reflect the integration of information that is relevant to the regulation of body temperature. Review Figure 40.19 46

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48. The Vertebrate Thermostat • Fever, which results from a rise in set point, helps the body fight infections. 48

49. The Vertebrate Thermostat • Adaptations in which set points are reduced to conserve energy include daily torpor and hibernation. Review Figure 40.20 49

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