Homeostasis and temperature control

• What is homeostasis?

  Maintaining the internal environment within limits
• Which factors are maintained in homeostasis?

  Temperature, pH, glucose concentration, water content
• What is the optimum internal temperature for the human body?

  37°C
• What happens to enzymes if the temperature is too high?

  They denature
• What occurs to enzyme activity if the temperature is too low?

  Enzyme activity decreases
• What are the steps in temperature control when blood temperature rises above 37°C?

  1. Hypothalamus starts cooling mechanisms
  2. Blood temperature lowers to 37°C
• What are the steps in temperature control when blood temperature lowers below 37°C?

  1. Hypothalamus starts warming mechanisms
  2. Blood temperature rises to 37°C
• How does the body respond when it is too hot?

  • Sweat glands release more sweat
  • Blood vessels dilate (vasodilation)
  • Nerve impulses cause hair erector muscles to relax (pilorelaxation)
• How does the body respond when it is too cold?

  • Shivering (skeletal muscles contract)
  • Blood vessels constrict (vasoconstriction)
  • Nerve impulses cause hair erector muscles to contract (pilorection)
• What is the role of sweat glands in temperature control?

  They release sweat to cool the body
• What is vasodilation?

  Blood vessels dilate to lose heat
• What is pilorelaxation?

  Skin hairs lie flat to lose heat
• What is shivering and its purpose?

  Muscle contractions that generate heat
• What is vasoconstriction?

  Blood vessels constrict to conserve heat
• What is pilorection?

  Skin hairs raise to trap insulating air
• Why do small animals lose heat easily?

  They have a greater surface area to volume ratio
• How do animals adapt to temperature control challenges?

  • Behavioral adaptations (e.g., huddling)
  • Physical adaptations (e.g., fur color)
• What adaptation do penguins use to combat cold environments?

  Huddle together to retain heat
• How do long-eared jerboas adapt to hot desert environments?

  They have large ears to cool down
• What adaptations do camels have for water conservation?

  Concentrated urine and dry feces
• Why do small animals have a higher metabolic rate?

  They lose heat easily due to size
• How does the environment affect the surface area to volume ratio of organisms?

  Similar volumes may have different surface areas
• How do organisms adapt their surface area to match metabolic demands?

  By increasing or decreasing surface area