Body temperature: Homeostasis and response: Biology: GCSE (9:1)

• Homeostasis


  The regulation of conditions in a cell or organism in order to optimally respond to internal and external changes

  
• Body temperature

  The amount of heat in the body which is controlled by homeostasis to ensure cells and enzymes function properly
• Enzymes and colder temperatures

  Enzymes work best at their optimum temperature, if it becomes too cold the enzymes will not have enough energy for successful reactions

  
• Enzymes and hotter temperatures

  Enzymes work best at their optimum temperature, if it becomes too hot the enzymes will denature and be unable to function

  
• Blood temperature


  Temperature of the blood is normally around 37 degrees celsius, which is the optimal temperature for human enzyme activity
• Thermoregulatory centre


  The area of the brain that is sensitive to the temperature of the blood

  
• Temperature receptors


  Cells which respond to temperature changes in the skin and body

  
• Nervous impulses

  Electrical signals that are sent from temperature receptors to the thermoregulatory centre during a response to temperature change
• Vasodilation


  The widening of blood vessels which increases the amount of blood near the skin's surface, allowing more heat to be transferred to the surroundings

  
• Sweat


  The liquid produced by the sweat glands which reduces heat energy from the skin as it evaporates

  
• Sweat glands


  Glands located in the skin that are responsible for the production of sweat

  
• Vasoconstriction

  The narrowing of blood vessels that reduces the amount of blood near the skin's surface, allowing less heat to be transferred to the surroundings

  
• Shivering

  The rapid involuntary contraction of skeletal muscle which leads to increased respiration rates and energy released as heat

  
• If body temperature is too high

  Blood vessels vasodilate and skin releases sweat
• If body temperature is too low

  Blood vessels vasoconstrict and shivering starts