Chapter 40: Physiology, Homeostasis, and Temperature Regulation CHAPTER 40 Physiology, Homeostasis, and Temperature Regulation

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

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

Chapter 40: Physiology, Homeostasis, and Temperature Regulation 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.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. Larger, more complex animals must do so by maintaining a constant internal environment.4

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Homeostasis: Maintaining the Internal Environment The internal environment consists of the extracellular fluids.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 40.1Organs and organ systems have specialized functions to keep certain aspects of the internal environment in a constant state. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Homeostasis: Maintaining the Internal Environment Homeostasis is the maintenance of constancy in the internal environmentHomeostasis is the maintenance of constancy in the internal environment It depends on the ability to control and regulate organ and organ system function.It depends on the ability to control and regulate organ and organ system function.7

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Tissues, Organs and Organ Systems Cells with a similar structure and function make up a tissue.Cells with a similar structure and function make up a tissue. There are four general types:There are four general types:  Epithelial  Connective  Muscle  Nervous. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Tissues, Organs, and Organ Systems Epithelial tissues are sheets of tightly connected cells that cover body surfaces and line hollow organs.Epithelial tissues are sheets of tightly connected cells that cover body surfaces and line hollow organs.10

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Tissues, Organs, and Organ Systems Connective tissues support and reinforce other tissues.Connective tissues support and reinforce other tissues. They generally consist of dispersed cells in an extracellular matrix.They generally consist of dispersed cells in an extracellular matrix.11

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Tissues, Organs, and Organ Systems Muscle tissues contract.Muscle tissues contract. There are three types:There are three types:  Skeletal  Cardiac  Smooth. 12

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Tissues, Organs, and Organ Systems There are two types of nerve cells:There are two types of nerve cells: Neurons generate and transmit electrochemical signalsNeurons generate and transmit electrochemical signals Glial cells provide supporting functions for neurons.Glial cells provide supporting functions for neurons.13

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Tissues, Organs, and Organ Systems Organs consist of multiple tissue types, and organs make up organ systems. Review Table 40.1Organs consist of multiple tissue types, and organs make up organ systems. Review Table

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Physiological Regulation and Homeostasis Regulatory systems have set points and respond to feedback information.Regulatory systems have set points and respond to feedback information. Negative feedback corrects deviations from the set pointNegative feedback corrects deviations from the set point Positive feedback amplifies responsesPositive feedback amplifies responses Feedforward information changes the set point. Review Figure 40.5Feedforward information changes the set point. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Temperature and Life Living systems require a range of temperatures between the freezing point of water and the temperatures that denature proteins.Living systems require a range of temperatures between the freezing point of water and the temperatures that denature proteins.19

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Temperature and Life Most biological processes and reactions are temperature-sensitive.Most biological processes and reactions are temperature-sensitive. Q 10 is a measure of temperature sensitivity. Review Figure 40.6Q 10 is a measure of temperature sensitivity. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Temperature and Life Animals that cannot avoid seasonal changes in body temperature have biochemical adaptations to compensate.Animals that cannot avoid seasonal changes in body temperature have biochemical adaptations to compensate. These enable animals to acclimatize to seasonal changes. Review Figure 40.7These enable animals to acclimatize to seasonal changes. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Maintaining Optimal Body Temperature Homeotherms maintain a fairly constant body temperature most of the time; poikilotherms do not.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 40.8Endotherms produce metabolic heat; ectotherms depend mostly on environmental sources of heat. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Maintaining Optimal Body Temperature Ectotherms and endotherms can regulate body temperature through behavior. Review Figure 40.9Ectotherms and endotherms can regulate body temperature through behavior. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Maintaining Optimal Body Temperature Heat exchange between a body and the environment is via:Heat exchange between a body and the environment is via:  radiation  conduction  convection  Evaporation Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Maintaining Optimal Body Temperature Ectotherms and endotherms can control heat exchange with the environment by altering blood flow to the skin. Review Figure 40.12Ectotherms and endotherms can control heat exchange with the environment by altering blood flow to the skin. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Maintaining Optimal Body Temperature Some ectotherms can produce metabolic heat to raise their body temperatures. Review Figure 40.13Some ectotherms can produce metabolic heat to raise their body temperatures. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Maintaining Optimal Body Temperature Some fish have circulatory systems that function as countercurrent heat exchangers to conserve heat produced by muscle metabolism. Review Figure 40.14Some fish have circulatory systems that function as countercurrent heat exchangers to conserve heat produced by muscle metabolism. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Thermoregulation in Endotherms Endotherms have high basal metabolic rates.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 40.15Over a range of environmental temperatures, the thermoneutral zone, their resting metabolic rates remain at basal levels. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation Thermoregulation in Endotherms When environmental temperature falls below a lower critical temperature, endotherms maintain their body temperatures through shivering and nonshivering metabolic heat production.When environmental temperature falls below a lower critical temperature, endotherms maintain their body temperatures through shivering and nonshivering metabolic heat production.39

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Thermoregulation in Endotherms When environmental temperature rises above an upper critical temperature, metabolic rate increases as a consequence of evaporative water loss.When environmental temperature rises above an upper critical temperature, metabolic rate increases as a consequence of evaporative water loss.40

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Thermoregulation in Endotherms Endotherms in cold climates have adaptations that minimize heat loss:Endotherms in cold climates have adaptations that minimize heat loss:  a reduced surface area-to-volume ratio  increased insulation. 41

Chapter 40: Physiology, Homeostasis, and Temperature Regulation Thermoregulation in Endotherms Endotherms may dissipate excess heat generated by exercise or the environment via evaporation.Endotherms may dissipate excess heat generated by exercise or the environment via evaporation. However, water loss can be dangerous to endotherms in dry environments.However, water loss can be dangerous to endotherms in dry environments.42

Chapter 40: Physiology, Homeostasis, and Temperature Regulation The Vertebrate Thermostat The vertebrate thermostat is in the hypothalamus.The vertebrate thermostat is in the hypothalamus. It has set points for activating thermoregulatory responses.It has set points for activating thermoregulatory responses. Hypothalamic temperature provides negative feedback information.Hypothalamic temperature provides negative feedback information.43

Chapter 40: Physiology, Homeostasis, and Temperature Regulation The Vertebrate Thermostat Cooling the hypothalamus induces blood vessel constriction and increased metabolic heat productionCooling the hypothalamus induces blood vessel constriction and increased metabolic heat production Heating it induces blood vessel dilation and active evaporative water loss.Heating it induces blood vessel dilation and active evaporative water loss. Thermoregulatory behaviors are induced by changes in hypothalamic temperature. Review Figure 40.18Thermoregulatory behaviors are induced by changes in hypothalamic temperature. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation The Vertebrate Thermostat Changes in set point reflect the integration of information that is relevant to the regulation of body temperature. Review Figure 40.19Changes in set point reflect the integration of information that is relevant to the regulation of body temperature. Review Figure

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Chapter 40: Physiology, Homeostasis, and Temperature Regulation The Vertebrate Thermostat Fever, which results from a rise in set point, helps the body fight infections.Fever, which results from a rise in set point, helps the body fight infections.48

Chapter 40: Physiology, Homeostasis, and Temperature Regulation The Vertebrate Thermostat Adaptations in which set points are reduced to conserve energy include daily torpor and hibernation. Review Figure 40.20Adaptations in which set points are reduced to conserve energy include daily torpor and hibernation. Review Figure

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