11.3.3 Homeostasis

• What is homeostasis?

  Maintenance of a constant internal environment
• What systems are responsible for homeostasis?

  The nervous system and hormones
• What does the internal environment refer to?

  Blood or tissue fluid surrounding cells
• What internal conditions need to be controlled for homeostasis?

  • Temperature
  • Glucose concentration
  • Water potential
• Why is temperature control important in homeostasis?

  To prevent enzyme denaturation and ensure reactions
• What happens if blood temperature is too high?

  Enzymes would denature
• What happens if blood temperature is too low?

  Particles lack kinetic energy for collisions
• Why is glucose concentration important in homeostasis?

  It provides energy for respiration
• What happens if glucose concentration is too high?

  Water leaves cells via osmosis
• What happens if glucose concentration is too low?

  Not enough glucose for respiration
• Why is water potential important in homeostasis?

  It affects cell hydration and function
• What happens if water potential is too high?

  Water enters cells and may cause bursting
• What happens if water potential is too low?

  Water leaves cells via osmosis
• How is homeostatic control achieved?

  • Through negative feedback mechanisms
  • Levels are adjusted back to the set point

  
• What is the role of the brain in thermoregulation?

  It contains receptors sensitive to blood temperature
• How do skin receptors contribute to thermoregulation?

  They send impulses to the brain about temperature
• What is the optimum body temperature for humans?

  37°C
• What happens when body temperature increases?

  Sweat glands release more sweat
• What is vasodilation?

  Widening of blood vessels to increase blood flow
• What occurs during vasodilation?

  More blood flows to the skin surface
• What happens when body temperature decreases?

  Muscles contract rapidly to shiver
• What is vasoconstriction?

  Narrowing of blood vessels to conserve heat

  
• What happens during vasoconstriction?

  Less blood flows to the skin surface

  
• What is the negative feedback cycle of thermoregulation?

  1. Body temperature increases or decreases
  2. Receptors detect changes
  3. Brain sends signals to effectors
  4. Effectors adjust temperature back to set point

  
• How is blood glucose concentration detected?

  By the pancreas
• What hormones are involved in blood glucose regulation?

  Insulin and glucagon

  
• What is a hormone?

  A chemical substance produced by a gland
• What happens when blood glucose concentration increases?

  The pancreas secretes insulin

  
• What does insulin do in the body?

  It helps cells take up glucose

  
• What is glycogen?

  A stored form of glucose in the liver
• What happens when blood glucose concentration decreases?

  The pancreas secretes glucagon

  
• What does glucagon do in the body?

  It stimulates the liver to release glucose

  
• What role does adrenaline play in blood glucose concentration?

  It increases blood glucose levels
• How does adrenaline affect glycogen?

  It causes glycogen to break down into glucose
• What are the treatments for Type 1 diabetes?

  • Monitoring blood glucose levels
  • Regular insulin injections
  • Controlling diet
  • Monitoring exercise levels
• What is Type 1 diabetes?

  A condition where the body does not produce insulin
• What happens to blood glucose levels in Type 1 diabetes?

  They cannot be controlled effectively
• What is the role of enzymes in blood glucose regulation?

  They convert glucose to glycogen in the liver
• What happens to respiration rates when blood glucose levels increase?

  Respiration rates of glucose decrease
• What is the summary of blood glucose regulation?

  1. Increase in blood glucose → Insulin released
  2. Decrease in blood glucose → Glucagon released
  3. Insulin promotes glucose uptake and storage
  4. Glucagon promotes glucose release into blood