Osmo Regulation 0.0 / 5 ? BiologyHomeostasisA2/A-levelOCR Created by: Om4rCreated on: 30-05-19 16:08 What does ADH stand for? Antidiuretic hormone 1 of 25 What is ADH? A hormone that controls the permeability of the collecting duct walls 2 of 25 What is an Osmoreceptor? A sensory receptor that detects changes in water potential 3 of 25 What is Osmoregulation? The control of the water potential in the body 4 of 25 What does Osmoregulation involve? Controlling levels of both water and salt in the body 5 of 25 What must osmoregulation occur? To prevent water entering the cells and causing lysis or leaving cells and causing crenation 6 of 25 What 3 sources does the body gain water from? Food, drink and metabolism 7 of 25 How is water lost from the body? In urine, sweat, faeces and water vapour exhaled in air 8 of 25 What organ is responsible for osmoregulation? The Kidney 9 of 25 How does the Kidney alter the volume of Urine produced? By altering the permeability of collecting ducts 10 of 25 What occurs if the body needs to conserve less water? Walls of collecting duct become less permeable, less water is reabsorbed and there's a greater volume of urine 11 of 25 What occurs if the body needs to conserve more water? Walls of collecting duct become more permeable, more water is reabsorbed into blood, smaller volume of urine produced 12 of 25 What controls the permeability of the collecting duct? ADH 13 of 25 What do the cells in the walls of the collecting duct have that allow ADH bind? Cells in the walls of the collecting duct have membrane bound receptors for ADH 14 of 25 What is the First stage for ADH to increase the permeability of the collecting duct? ADH binds to the receptors causing a chain of enzyme controlled reactions 15 of 25 What effect does the binding of ADH to receptors have? Leads to vesicles containing aquaporins to fuse with the cell surface membrane making walls more permeable to water 16 of 25 What occurs when the body is hydrated ? ADH levels fall, cell surface membrane folds inwards (invaginates) creating new vesicles that remove the aquaporins from the membrane 17 of 25 Where are osmoreceptors found? In the Hypothalamus 18 of 25 What do osmoreceptors respond to? The effects of osmosis 19 of 25 What happens to osmoreceptors when the water potential of blood is low? The osmoreceptor cells lose water by osmosis and shrink 20 of 25 What occurs as a result of osmoreceptors shrinking? Stimulates neurosecretory cells in the Hypothalamus 21 of 25 Where is ADH manufactured? In the cell body of neurosecretory cells in the hypothalamus 22 of 25 What happens when ADH is produced? They release ADH, it moves down the axon to the terminal bulb in the posterior pituitary gland where it's stored in vesicles 23 of 25 What happens when neurosecretory cells are stimulated by osmorecpetors? Neurosecretory cells carry action potentials down their axons and cause the release of ADH by exocytosis 24 of 25 What happens once the water potential of the blood rises again? Less ADH is released and ADH is slowly broken down 25 of 25
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