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Osmoregulation

Osmoregulation. Spec. (d) the control of the water potential of the blood To include the role of osmoreceptors in the hypothalamus, the posterior pituitary gland, ADH and its effect on the walls of the collecting ducts. Learning Objective Success Criteria.

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Osmoregulation

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  1. Osmoregulation

  2. Spec • (d) the control of the water potential of the blood • To include the role of osmoreceptors in the hypothalamus, the posterior pituitary gland, ADH and its effect on the walls of the collecting ducts.

  3. Learning ObjectiveSuccess Criteria Explain the control of water potential of the blood • Explain how the water potential of the blood is controlled, including the role of osmoreceptors in the hypothalamus, the posterior pituitary gland, ADH and its effect on the wall of the collecting duct

  4. State whether water is gained or lost from each item

  5. Osmoregulation • Osmoregulation is the control of water levels and salt levels in the body. • Correct balance must be maintained to prevent problems with osmosis

  6. Permeability of the Collecting Duct • In the absence of ADH the collecting duct wall is impermeable to water • The walls of the collecting duct respond to the level of antidiuretic hormone (ADH) in blood.

  7. The effect of ADH on the collecting duct wall

  8. TASK: Turn the Following points into a storyboard • 1. ADH is detected by cell surface receptors • 2. Enzyme controlled reactions • 3. Vesicles containing water permeable channels (aquaporins) fuse to membrane • 4. More water can be reabsorbed

  9. Osmoreceptors • The water potential of the blood is monitored by osmoreceptors in the hypothalamus of the brain • Negative water potential causes the OR to lose water and shrink which stimulates the NS cells Neurosecretory cells Osmoreceptor - Ψ H20 H20 Osmoreceptor ADH

  10. Hypothalamus Posterior Pituitary Gland Neurosecretory cells When neurosecretory cells are stimulated they send action potentials down their axons that cause the release of ADH ADH ADH ADH ADH

  11. ADH • ADH then enters the blood capillaries near the PPG and acts on the cells of the collecting ducts

  12. Negative Feedback • Once the water potential rises less ADH is released • ADH is slowly broken down therefore there will be less in the blood so collecting ducts receive less stimulation

  13. TASK • Complete the flow diagram

  14. Extension Activity • Biofactsheet

  15. Plenary: PPQs

  16. PPQ – ADH 2013 • See Print out

  17. Markscheme

  18. Markscheme continued

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