B3.11 Thermoregulation

• What is thermoregulation?

  Control of internal body temperature
• Why do we need to regulate our body temperature?

  To allow our cells to function properly
• Which part of the brain controls thermoregulation?

  The hypothalamus
• What does homeostasis refer to?

  Maintaining a stable internal environment
• What is the ideal body temperature for enzyme function?

  37 degrees Celsius
• What happens to enzymes below 37 degrees Celsius?

  Their activity slows down
• What happens to enzymes above 37 degrees Celsius?

  They start to denature
• What is the thermoregulatory sensor?

  A part of the hypothalamus acting as a thermostat
• Where are temperature receptors mostly found in the body?

  In the skin and blood vessels
• How does the brain respond if it detects the body is too hot?

  It sends signals to cool the body down
• How does the brain respond if it detects the body is too cold?

  It brings about changes to warm the body up
• What mechanisms does the body use to warm up?

  • Vasoconstriction of blood vessels
  • Contraction of erector muscles
  • Shivering to generate heat
• What is vasoconstriction?

  Constriction of blood vessels near the skin
• What is the purpose of contracting erector muscles?

  To trap insulating air and retain heat
• How does shivering help warm the body?

  It generates heat through muscle contraction
• What happens to the erector muscles when cooling down?

  They relax, allowing hairs to fall flat
• What mechanisms does the body use to cool down?

  • Relaxation of erector muscles
  • Vasodilation of blood vessels
  • Sweating to evaporate heat
• What is vasodilation?

  Expansion of blood vessels near the skin
• How does sweating cool the body?

  Evaporation of sweat takes away heat
• Which word refers to the control of our internal body temperature?

  Thermoregulation 
• What is sweat composed of?

  A mixture of water and salts
• Why does evaporation of water require energy?

  To change water from liquid to gas
• What is the result of sweat evaporation on body temperature?

  It leaves the body cooler
• The human body has to be kept around which temperature? 

  37°C
• What type of feedback is involved in thermoregulation?

  Negative feedback
• Why do we have to maintain our body temperature at 37°C?

  It's the optimum temperature for enzymes to function
• Where in the body is the thermoregulatory centre located?

  Brain
• What is the role of receptors in the body? 

  To detect changes in conditions 
• Temperature receptors are found throughout the body. 

  Where are the two main places they're found?

  • Skin
  • Blood vessels
• Which of the methods below serve to warm the body up?

  • Constrict blood vessels near the skin
  • Contract erector muscles and raise body hairs
  • Shivering
• Is information about skin temperature sent to the brain by the nervous system, or endocrine system?

  Nervous
• Explain how shivering warms the body.

  Shivering involves muscles contracting and relaxing automatically. This requires a lot of energy from respiration, which in the process releases a lot of heat energy as waste. 
• To minimise heat loss we contract erector muscles in the skin, which raises our hairs. This traps a layer of insulating air and so means that less heat energy is lost.
• Which of the methods below help cool us down?

  • Dilate blood vessels near the skin
  • Sweating
  • Relax erector muscles and lower body hairs
• What is vasodilation?

  Blood vessels near the skin become wider, increasing the flow of blood in the skin capillaries
• How does sweat keep us cool?

  As sweat evaporates it removes heat energy from the skin