Osmoregulation 0.0 / 5 ? BiologyCellular processesA2/A-levelOCR Created by: Steff06Created on: 03-03-16 20:27 What is the definition of osmoregulation? The control of salt and water levels in the body. 1 of 14 How is water gained and lost in the body? Gained through food, drink and metabolism. Lost through urine, faeces, sweat and water vapour in exhaled air. 2 of 14 What happens when conserving less water? The walls of the collecting duct become less permeable to water. 3 of 14 What is the effect of less permeability to water? Less water will be reabsorbed and more urine will be produced. 4 of 14 What are the walls of the collecting duct responsive to? Levels of antidiuretic hormone (ADH) in the blood. 5 of 14 What does ADH do and what does this cause? Binds to receptors in wall and causes enzyme-controlled reactions. 6 of 14 What do the reactions cause and what effect does this have on the wall? Causes insertion of vesicles containing aquaporins into cell surface membrane. Makes wall more permeable to water. 7 of 14 What is the effect of less ADH? Cell surface membrane folds inwards to create vesicles that remove aquaporins from membrane. 8 of 14 What is water potential measured by? Osmoreceptors in the hypothalamus. 9 of 14 What happens when water potential is low? Osmoreceptor cells lose water by osmosis. 10 of 14 What cells release ADH and how do they do this? Neurosecretory cells release ADH by sending action potentials down their axons. 11 of 14 What will ADH enter and do? Enters blood capillaries and act on the walls of the collecting duct. 12 of 14 What happens when water potential rises? Less ADH is released. 13 of 14 What then happens to the ADH? It is then broken down to prevent continuous stimulation of the collecting duct. 14 of 14
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