More On The Kidneys Flashcards
what is the amount of water reabsorbed into the body by the nephrons controlled by
anti-diuretic hormone (ADH)
how does ADH get released
- the brain monitors the water content of the blood
- and instructs the pituitary gland to release ADH into the bloodstream
- according to how much is needed
what does ADH actually do and what is the effect of what it does
- it makes the collecting ducts of the nephrons more permeable
- so that more water is reabsorbed back into the blood
- this stops the body from becoming dehydrated
what is the whole process of water content regulation ultimately controlled by
a negative feedback system
what is the negative feedback system look like when water from the body is lost or water content is little
- brain detects water loss and low water content
- pituitary gland releases more ADH
- more ADH increases the permeability of the collecting duct
- causing the kidneys to reabsorb more water back into the blood
what is the negative feedback system look like when water from the body is gained or water content is high
- brain detects water gain or high water content
- pituitary gland releases less ADH
- less ADH decreases the permeability of the collecting duct
- causing the kidneys to reabsorb less water back into the blood
what happens when the amount of sodium ions in the blood increases and what is the response
- the concentration of water int he blood will fall
- the brain then detects that the blood needs more water
- so it will release more ADH
- this increases the permeability of the collecting duct so more water is reabsorbed back into the blood
- so the water content of the blood will rise and the sodium ion concentration will therefore drop
what is the effect of having kidney failure
you cant filter the waste out of your blood properly
what do people with failed kidneys use to filter their blood for them
a dialysis machine
why does dialysis have to be done regularly
- to keep dissolved substances at the right concentrations
- and remove waste
why arent salts and glucose removed from the blood when attached to a dialysis machine
- because the dialysis fluid has the same concentration of salts and glucose as blood plasma
- meaning they wont be removed from the blood as there is no concentration difference or gradient
how do dialysis machines work
- blood from the person is drawn into the machine
- it goes through the selectively permeable barrier
- where waste products diffuse out into the dialysis fluid
- the dialysis fluid has a constant supply of it coming in and out to maintain a high concentration difference of the waste
- the filtered blood flows back into the person
how does the selectively permeable barrier of a dialysis machine work
- the barrier is permeable to things like ions and waste substances
- but not big molecules like proteins (how it works in the membranes of the kidneys)
- so the waste substances, excess ions and water from the blood move across the membrane into the dialysis fluid
- while the cells and proteins stay in the blood
what is currently the only cure for kidney disease
having a kidney transplant
where do healthy kidneys that are used in kidney transplants come from
- people who have died suddenly like in a car accident
- and who are on the organ donor register or carry a donor card
- provided their relatives approve
