Principles of Human Physiology - The Endocrine System

Principles of Human Physiology: The Endocrine System

Chapter Outline

• 21.6 Thermoregulation

Learning Outcomes

• Describe how the body regulates body temperature.

21.6 Thermoregulation

• Homeothermic:
  • Definition: Organisms that maintain a relatively constant internal temperature.
  • Advantages:
  • Stabilized enzyme activity.
• Endothermic:
  • Definition: Organisms that generate heat from within.

Temperature Balance

• Equation: Heat gain = heat loss.
  • Negative Balance:
  • Definition: Heat gain < heat loss.
  • Positive Balance:
  • Definition: Heat gain > heat loss.

Regulation of Body Temperature

• Effectors involved in temperature regulation:
  • Sweat glands:
  • Function: Activate to cool the body by secreting sweat.
  • Muscles:
  • Skeletal muscles:
    • Function: Generate heat through shivering if cold.
  • Smooth muscle of cutaneous blood vessels:
    • Function:
    • If hot - vessels dilate to promote heat loss through increased blood flow (sweating).
    • If cold - vessels constrict to preserve heat.

Thermoregulation Process

• Events occurring in the body during thermoregulation:
  • Process overview:
  • Changes in external temperature detected by thermoreceptors.
  • Information sent to the hypothalamus, which integrates this data and initiates a physiological response.
  • Result: Adjustments made to body temperature to maintain homeostasis.

Key Terms and Information

• Thermoreceptors: Specialized sensors that detect changes in temperature.
• Hypothalamus: A brain region involved in thermoregulation, overseeing the maintenance of body temperature.
• Physiological Response: Actions taken by the body to return to a set temperature range, such as sweating or shivering.