Kidneys Flashcards
what do kidneys make
urine
what does urine contain
water, urea, salts
what happens when someone has kidney failure
their blood will contain a higher concentration of water, ions and urea than it should
describe kidney diyalysis
- if a person has kidney failure, their blood will contain a higher concentration of water, ions and urea than it should
- in kidney dialysis, the patients blood passes over a semi permeable membrane; which allows urea, ions and water through, but not large molecules like proteins/blood cells
- on the other side of the membrane we have dialysis fluid
- there is a concentration gradient for urea
- do the urea diffuses from the blood into the dialysis fluid
what does the other side of the membrane contain
- dialysis fluid
what does dialysis fluid contain
normal conc of water, ions, glucose and contains NO UREA
how does urea get from the body to the dialysis fluid
it diffuses from the blood into the dialysis fluid
why is the dialysis fluid constantly refreshed
so that there is always a large concentration gradient for urea
disadvantages of kidney dialysis
- not a pleasant experience
- patients have to have dialysis sessions 3 times a week, 3-4 hrs
- may cause blood clots
- expensive for NHS to run
- controlled diet
advantages of kidney dialysis
greatly reduced levels of urea – it is ‘cleaned blood’
- no overall change in blood glucose levels
the correct water and ion balance maintained or restored (with only excess ions removed)
- no shortage of dialysis machines
advantages of kidney transplants
- patient can live a normal life, no controlled diet
- overall cheaper for the NHS
disadvantages of kidney transplants
- there is a shortage of donors
- need to regularly take immunosuppresant drugs to stop your body rejecting the organ
- there is a risk that patients immune system may reject the donor kidney
how does the digestion of proteins help the body
allows amino acids (which are deaminated to form ammonia) to be excreted safely
what is osmosis
the movement of water molecules from a dilute to concentrated area through a partially permeable membrane
what happens if blood becomes to dilute
water moves into cells via osmosis
what happens if the blood becomes too concentrated
water moves out of the body cells via osmosis
what happens if body cells lose or gain too much water by osmosis
they dont work efficiently
what do the kidneys do if the blood is too dilute
they remove the excess water and produce a greater volume of urine
what else other than water is removed in urine
urea and excess ions
describe how the kidney removes stuff
- blood enters the kidney through an artery and this blood contains the waste product urea
- the kidney removes all this urea as well as excess ions and excess water
- these leave the kidney as urine and this is stored in the bladder
- blood then leaves the kidney through a vein
- blood now contains no urea
how do the kidneys adjust the level of molecules in the blood
- blood passes through the capillaries, here, small molecules are filtered out of the blood (including urea, ions, glucose)
- these pass through a tube
- now all of the glucose, some of the ions and some of the water is re absorbed back into the blood (SELECTIVE REABSORPTION)
- urea, excess ions and excess water are released as urine
what are proteins
long chains of amino acids
what happens when we digest proteins
amino acids pass into the blood
how are proteins broken down
- amino acids pass through the blood
- liver breaks down the excess amino acids and produces the chemical ammonia
- this process is called deamination
- ammonia is a very toxic chemical so the liver immediately converts it to urea which can be safely excreted by the kidneys
why, when using kidney dialysis, will the concentration of ions and water return to normal
because some of the persons ions and water will also diffuse into the dialysis fluid
