controlling body temperature

• how do people lose fingers due to frostbite?

  The body responds to extreme cold by narrowing the blood vessels that supply the extremities so there is increased blood flow to vital organs. the extremities can then get so cold that tissue fluid freezes and leads to tissue death
• what is the normal body temperature?

  37°c as this is optimum temperature for your enzymes, small temperature changes can stop the body from working efficiently
• what happens due to exposure to extreme cold?

  It can reduce core body temperature and causes enzyme reactions to occur too slowly. respiration does not release enough energy and cells begin to die
• what body temperature does hypothermia come at?

  Below 35°c
• what can cause the body to overheat?

  Exposure to very high temperatures and some infections, if the core body temperature rises above 40-42°c then enzymes may denature so body reactions cannot occur and in extreme circumstances you can die
• how is body temperature controlled and what is it a type of?

  The thermoregulatory centre in the brain is responsible for regulating body temperature and it relies on signals received from receptor cells in your skin (to monitor external temperature) and from internal receptor cells (to monitor temperature of your blood). when a change in temperature is detected, the brain causes different parts of the body to respond by sending impulses to its effectors and these responses then return the body back to its normal temperature. it is an example of homeostasis
• which body system monitors and controls internal body temperature?

  Thermoregulatory centre in the brain
• what happens when you get too hot?

  Body hairs lay lower, sweat glands produce more sweat and blood vessels near skin surface widen
• how do body hairs laying low help cool the body down?

  This prevents an insulating layer of air being trapped around the body
• how does sweating reduce your temperature?

  Sweat is mainly made of water but also contains salt and urea (waste material) and as the water in sweat evaporates, energy is transferred by heating from your body to the environment which reduces your temperature
• how does blood vessels widening allow you to cool down?

  Blood vessels supplying capillaries near the surface of your skin widen, which is known as vasodilation, this increases blood flow through capillaries which increases heat loss by radiation
• what happens when you get too cold?

  Body hairs rise, sweating stops, blood vessels near skin surface narrow, shivering begins
• what do rising body hairs do?

  Trap a layer of air close to the skin which insulates the body
• how does no sweat warm the body up?

  There is no unnecessary evaporation or water loss
• how does blood vessels near skin narrowing reduce heat loss?

  Vasoconstriction reduces blood flow through capillaries which reduces heat loss and send blood to internal organs
• how does shivering warm you up?

  Shivering occurs when your muscles contract and relax quickly, which makes your cells respire more quickly which transfers extra energy by heating
• difference between vasodilation and vasoconstriction?

  Vasodilation: widening of blood vessels. Vasoconstriction: narrowing of blood vessels.
• state 3 changes in the skin when you are too hot?

  sweating, hair lies flat, skin turns red due to increased blood flow