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Thermoregulation Objective: * Identify the different structures on the diagram of a skin

Thermoregulation Objective: * Identify the different structures on the diagram of a skin ** Describe how body temperature is kept constant *** Explain thermoregulation in terms ofvasodilation and vasoconstriction. Name the largest organ of the body. What are its functions?.

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Thermoregulation Objective: * Identify the different structures on the diagram of a skin

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  1. Thermoregulation Objective: * Identify the different structures on the diagram of a skin ** Describe how body temperature is kept constant *** Explain thermoregulation in terms ofvasodilation and vasoconstriction

  2. Name the largest organ of the body. What are its functions? Protects body from damage Stops pathogen from entering Prevents too much water loss Detects changes in temperature Detects pressure (touch) and pain Loses heat by conduction, convection and radiation

  3. the hypothalamus acts like the programmer in the central heating system. messages from the brain go to parts of the body that can have an effect - the effectors. temperature sensors in the skin are like the thermostats in the heating system. a ‘message’ from temperature sensors in the skin

  4. Keepingconstant temperature To keep warm: • Shivering – uses energy • Releasing energy from food • Vasoconstriction • Exercising • To keep cool: • Sweating reduces temperature • Removing energy from body • Vasodilation • Sit or lay down Controlled by the hypothalamus

  5. body temperature normal body temperature falls hair stands up and a goose bump appears hair lies flat on the skin the muscle is relaxed the muscle contracts

  6. Sweating • Sweat is produced in sweat glands • Sweat on your skin evaporates and it takes heat energy from your body to turn the liquid to a gas. This cools you down.

  7. Hypothalamus (of a sheep)

  8. Skin based effectors

  9. Skin based effectors

  10. Skin based effectors – responding to heat gain

  11. Skin based effectors – responding to heat loss

  12. Skin based effectors

  13. Effectors

  14. Shivering

  15. Responding to vigorous exercise • ·stimulus is the increase in blood temperature • ·this is caused by exercise/increased respiration/muscle contraction • ·the increase blood temperature is detected by receptors in the hypothalamus • ·the hypothalamus also acts as the co-ordinator • ·the effectors are muscles of arterioles • ·and sweat glands • ·response to arteriole muscles stimulation is vasodilation • ·which causes increased blood flow to the skin capillaries • ·which causes increased heat loss by radiation • ·response to sweat gland stimulation is increased sweating • ·which causes increased heat loss by the latent heat of evaporation

  16. Exam questions 1. All living organisms exist in changing external environments and many are able to control their internal environments. (a) Explain how the body of a mammal may respond to a rise in the environmental temperature. (8marks)

  17. Exam answers • Thermoreceptors in skin; nervous impulse;to hypothalamus; blood temperature monitored;heat loss centre involved; vasodilation / dilation of arterioles;more blood to skin surface; more heat lost by radiation;piloerector muscles relax; hairs flatten on skin surface;less insulation; sweating initiated / increased;panting / licking; evaporation removes latent heat; • thinner fur; migration; drop in metabolic rate / use less brown fat;accept long term changes such as less fat deposition;accept one behavioural process; • max. 8

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