Table of Contents

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
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6
Figure 40.1
figure 40-01.jpg

• Figure 40.1

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.
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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
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Figure 40.2
figure 40-02.jpg

• Figure 40.2

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Tissues, Organs, and Organ Systems

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

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

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

• Organs consist of multiple tissue types, and
  organs make up organ systems. Review Table 40.1
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Table 40.1 Part 1
table 40-01a.jpg

• Table 40.1 Part 1

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

• 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
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Figure 40.5
figure 40-05.jpg

• Figure 40.5

19
Temperature and Life

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

• Most biological processes and reactions are
  temperature-sensitive.
• Q10 is a measure of temperature sensitivity.
  Review Figure 40.6
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Figure 40.6
figure 40-06.jpg

• Figure 40.6

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
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Figure 40.7
figure 40-07.jpg

• Figure 40.7

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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
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Figure 40.8
figure 40-08.jpg

• Figure 40.8

26
Maintaining Optimal Body Temperature

• Ectotherms and endotherms can regulate body
  temperature through behavior. Review Figure
  40.9
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Figure 40.9
figure 40-09.jpg

• Figure 40.9

28
Maintaining Optimal Body Temperature

• Heat exchange between a body and the environment
  is via
• radiation
• conduction
• convection
• Evaporation Review
  Figure 40.11
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Figure 40.11
figure 40-11.jpg

• Figure 40.11

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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
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Figure 40.12
figure 40-12.jpg

• Figure 40.12

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Maintaining Optimal Body Temperature

• Some ectotherms can produce metabolic heat to
  raise their body temperatures. Review Figure
  40.13
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Figure 40.13
figure 40-13.jpg

• Figure 40.13

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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
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Figure 40.14 Part 1
figure 40-14a.jpg

• Figure 40.14 Part 1

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Figure 40.14 Part 2
figure 40-14b.jpg

• 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
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Figure 40.15
figure 40-15.jpg

• Figure 40.15

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

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Thermoregulation in Endotherms

• Endotherms in cold climates have adaptations that
  minimize heat loss
• a reduced surface area-to-volume ratio
• increased insulation.
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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.
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The Vertebrate Thermostat

• The vertebrate thermostat is in the hypothalamus.
  
• It has set points for activating thermoregulatory
  responses.
• Hypothalamic temperature provides negative
  feedback information.
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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
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Figure 40.18
figure 40-18.jpg

• Figure 40.18

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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Figure 40.19
figure 40-19.jpg

• Figure 40.19

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The Vertebrate Thermostat

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

• Adaptations in which set points are reduced to
  conserve energy include daily torpor and
  hibernation.
  Review Figure 40.20
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Figure 40.20 Part 1
figure 40-20a.jpg

• Figure 40.20 Part 1

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Figure 40.20 Part 2
figure 40-20b.jpg

• Figure 40.20 Part 2