Osmoregulation Flashcards
What is negative feedback?
mechanisms to restore any deviations from normal in a system back to its original state
Why is osmoregulation important?
-HYPERTONIC: too much water leaves cells, crenation, chemical reactions etc, cant occur
- HYPOTONIC: water moves into cells, so cells burst, lysis.
What is hypertonic?
blood has too low water potential (less water more ions)
What is hypotonic?
blood has too high water potential (more water less ions)
What might cause blood to be hypertonic?
- lots of ions in food
- not enough water
- sweating
What might cause blood to be hypotonic?
- too much water
- not enough ions
What detects change in water potential?
osmoreceptors in the hypothalamus
Where is ADH produced?
osmoreceptors in the hypothalamus
What stimulates MORE ADH to be produced?
water leaves osmoreceptor cells, stimulating ADH to be produced
Where is ADH released?
posterior pituitary gland
What effect does ADH have?
- increases the permeability of the walls of the distal convoluted tubule and collecting ducts
- so more water is reabsorbed
What happens when ADH reaches the kidneys?
- ADH binds to complementary receptors on the cell membranes of epithelial cells of the collecting duct
What happens when ADH binds to receptors?
activates phosphorylase enzyme in the cells
What does phosphorylase cause to happen?
- vesicles containing aquaporins
- fuse to cell membranes, integrating more aquaporins into the membrane
What are aquaporins?
channel proteins that allow water to pass through
