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Thermoregulation

Thermoregulation. GROUP STARTER: WHAT’S THE LINK???. How would your body change in these environments?. When we feel hot…. When we are cold…. We need to lose heat faster as our core body temperature is in danger of rising and becoming too hot (>37 °C) .

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Thermoregulation

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  1. Thermoregulation

  2. GROUP STARTER: WHAT’S THE LINK???

  3. How would your body change in these environments?

  4. When we feel hot… When we are cold… We need to lose heat faster as our core body temperature is in danger of rising and becoming too hot (>37°C). We need to warm up faster as our core body temperature is in danger of becoming too cold (<37°C).

  5. DEATH from HYPERTHERMIA 420C 390C 370C 350C 330C 280C 250C Dehydration and heat stroke Unusual sweating, fever NORMAL Shivering Difficulty in staying awake Breathing stops DEATH from HYPOTHERMIA

  6. As we got through the next few slides…. • Try and fill in your worksheet!

  7. Role of Hypothalamus • Acts as a thermostat • Sensitive to nerve impulses • Received from hot and cold thermoreceptors in the skin • Hypothalamus also possesses central thermoreceptors -sensitive to changes in temperature of blood -these reflect changes in temperature of body core

  8. Thermo-regulatory centre in the brain • Responds to information • Sends appropriate nerve impulses to effectors • These trigger corrective feedback mechanisms • Return body temperature to normal level (set point)

  9. Role of skin • Leading role in temperature regulation • Responds to nerve impulses from the hypothalamus • Skin acts as an effector

  10. Involuntary responses • Mechanisms of temperature regulation are involuntary • Controlled at a subconscious level by the hypothalamus

  11. Vasodilation • Skin becomes dilated • Large volume of blood flows through capillaries near skin surface • Blood able to lose heat by radiation

  12. Increase in rate of sweating • Heart energy from body • Convert sweat into water vapour • Lowers body temperature

  13. Vasoconstriction • Arterioles leading to skin become constricted • Small volume of blood flow to surface capillaries • Little heat lost by radiation

  14. This means less heat is lost from the surface of the skin If the temperature falls, the blood vessel constricts (gets shut off).

  15. Decreased rate of sweating • Sweating reduced to a minimum • Heat conserved

  16. Contraction of erector muscles • Wide layer of air trapped between body and external environment • Air poor conductor of heat • Layer of insulation reduces heat loss

  17. Voluntary responses • Body temperature drops below normal • Nerve impulses transmit this information to cerebrum • Person ‘feels cold’ • Takes appropriate action to correct problem -puts on a jacket -has a cup of tea etc.

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