B5__Homeostasis-and-Response
If too much water moves into cells by osmosis then the cell could burst. If too much moves out the cell could shrink. Either way they do not function properly.
The Kidneys
The kidneys role is to filter out waste products of the blood and selectively reabsorb useful substances. Products that are processed in the kidneys include water, ions and urea.
ADH
Anti-diuretic hormone (ADH) is a hormone involved in the control of the loss of water as urine. It is released into the pancreas by the pituitary gland when a receptor in the brain detects that the blood is too concentrated.
- It travels in the bloodstream to the kidney tubules
- An increased amount of ADH reaching the tubules increases their permeability to water, so more moves out of the tubule and back into the bloodstream
- This results in a smaller volume of more concentrated (yellow) urine and the blood becoming less concentrated as more water moves into it.
This is an example of a negative feedback loop, because if the concentration of the blood increases/decreases, more/less ADH is secreted to reverse this change