the kidneys Flashcards
2 ways the body gains water
- eating
- drinking
3 ways the body loses water
- via the lungs when we exhale
- sweat lose water through the skin
(sweat contains water, ions, urea) - urine
explain how the kidney produces urine
- filtration
water, urea, ions, and glucose moves from the capillary into the tubule as a result of high blood pressure
large molecules like protein remain in the blood
- selective reabsorption
all glucose, some ions, and some water are reabsorbed into the blood from the tubule - urine formation
some ions, some water, and all the urea are transported to the bladder for excretion as urine
after urine has been excreted what happens to the concentration of glucose, ions and urea in the blood
- concentration of GLUCOSE in the blood doesn’t change
the kidneys filter glucose out of the blood then reabsorb it all back into the blo0d - concentration of IONS in the blood has decreased
the kidneys filter ions out of the blood then they reabsorb some back into the blood depending on the needs of the body - concentration of UREA in the blood falls virtually to zero as all of it is excreted in the urine after being filtered out
how does the body deal with excess amino acids
when we digest proteins amino acids pass into the blood we often eat more protein than needed
so the liver breaks down the excess amino acids to produce ammonia (THIS PROCESS IS CALLED DEAMINATION)
ammonia is a very toxic chemical so the liver converts it to urea which is then excreted by the kidneys
why do people have to go on kidney dialysis
their kidneys fail so cannot monitor the amount of urea, water, ions in the blood
explain how kidney dialysis works
- when a person has kidney failure their blood will contain a higher concentration of water, ions, and urea than it should
- in kidney dialysis a patient’s blood passes over a semi-permeable membrane this allows urea, ions, and water through but will not allow larger molecules like proteins to pass through (blood cells are also too large to pass through the membrane)
- on the other side of the membrane there is kidney dialysis fluid (this contains the normal concentration of water and ions but doesn’t contain any urea)
- there is a concentration gradient for urea so it diffuses from the blood into the dialysis fluid
- the dialysis fluid is constantly refreshed to maintain a large concentration gradient for the diffusion of urea
- some of the water and ions in the blood diffuse from the blood into the dialysis fluid
BECAUSE OF THIS THE CONCENTRATION OF WATER AND IONS IN THE PERSONS BLOOD WILL RETURN TO NORMAL
disadvantages of kidney dialysis
- can be inconvenient
(patients have to go to the hospital several times a week) - have to eat a controlled diet (so they don’t produce too much urea)
- expensive in the long term
POSSIBLY BETTER ALTERNATIVE IS A KIDNEY TRANSPLANT????
explain the process of a kidney transplant
- the diseased kidney is removed from the patient during an operation and is replaced with a healthy one from a donor
disadvantages of kidney transplant
- the donated kidney can be rejected
(due to the body recognizing the new kidney as foreign) - shortage of donors and the transplant list is long
- the risk of infection with surgery
- have to take anti-rejection drugs for the rest of their life
advantages of kidney dialysis
+ no shortage of dialysis machines
+ no surgery so no risk of infection from that
advantages of kidney transplant
+ patients can live a normal live
+ only expensive initially
