Homeostasis; Thermoregulation A2/A level Biology

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  • Created by: evaabarry
  • Created on: 01-03-22 18:05
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  • Homeostasis: Thermoregulation
    • Receptors that detect changes in core temperature= THERMORECEPTORS
      • Found ;  Hypothalamus in the brain
      • Thermoreceptors in skin detect changes in external environment
    • When receptors detect temperature rise
      • 1.) Impulses sent along motor neurones to arterioles in skin , causing muscle in their walls to relax.   - causes arterioles to widen (vasolidation) allowing more blood to flow to capillaries at skin surface.          - Allows more heat to be lost from blood to environment
      • 2.) Impulses sent along motor neurones to sweat glands in skin, causing more secretion of sweat.               - Water in sweat evaporates, taking heat from skin, therefore cooling the body
    • If receptors detect temperature fall
      • 1.) Impulses sent along motor neurones to arterioles in skin , causing arterioles to become narrower (Vasoconstriction) , allowing less blood flow to capillaries at skin surface.     - Allows heat loss from blood to environment
      • 2.) Impulses sent along sensory neurones to skeletal muscles , causing contraction and relaxing rapidly (shivering) , generating heat thats transferred to body
      • 3.) In non human mammals ; erector muscles stimulated to contract, raising hairs on end and trapping a layer of air between hairs on skin.            -Air is good insulator, reduces heat loss from body
    • This control mechanism is a good example of negative feedback

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