Kidneys

Question 1

what do kidneys make

Answer 1

urine

Question 2

what does urine contain

Answer 2

water, urea, salts

Question 3

what happens when someone has kidney failure

Answer 3

their blood will contain a higher concentration of water, ions and urea than it should

Question 4

describe kidney diyalysis

Answer 4

• 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

Question 5

what does the other side of the membrane contain

Answer 5

• dialysis fluid

Question 6

what does dialysis fluid contain

Answer 6

normal conc of water, ions, glucose and contains NO UREA

Question 7

how does urea get from the body to the dialysis fluid

Answer 7

it diffuses from the blood into the dialysis fluid

Question 8

why is the dialysis fluid constantly refreshed

Answer 8

so that there is always a large concentration gradient for urea

Question 9

disadvantages of kidney dialysis

Answer 9

• 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

Question 10

advantages of kidney dialysis

Answer 10

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

Question 11

advantages of kidney transplants

Answer 11

• patient can live a normal life, no controlled diet
• overall cheaper for the NHS

Question 12

disadvantages of kidney transplants

Answer 12

• 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

Question 13

how does the digestion of proteins help the body

Answer 13

allows amino acids (which are deaminated to form ammonia) to be excreted safely

Question 14

what is osmosis

Answer 14

the movement of water molecules from a dilute to concentrated area through a partially permeable membrane

Question 15

what happens if blood becomes to dilute

Answer 15

water moves into cells via osmosis

Question 16

what happens if the blood becomes too concentrated

Answer 16

water moves out of the body cells via osmosis

Question 17

what happens if body cells lose or gain too much water by osmosis

Answer 17

they dont work efficiently

Question 18

what do the kidneys do if the blood is too dilute

Answer 18

they remove the excess water and produce a greater volume of urine

Question 19

what else other than water is removed in urine

Answer 19

urea and excess ions

Question 20

describe how the kidney removes stuff

Answer 20

• 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

Question 21

how do the kidneys adjust the level of molecules in the blood

Answer 21

1. blood passes through the capillaries, here, small molecules are filtered out of the blood (including urea, ions, glucose)
2. these pass through a tube
3. now all of the glucose, some of the ions and some of the water is re absorbed back into the blood (SELECTIVE REABSORPTION)
4. urea, excess ions and excess water are released as urine

Question 22

what are proteins

Answer 22

long chains of amino acids

Question 23

what happens when we digest proteins

Answer 23

amino acids pass into the blood

Question 24

how are proteins broken down

Answer 24

1. amino acids pass through the blood
2. 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

Question 25

why, when using kidney dialysis, will the concentration of ions and water return to normal

Answer 25

because some of the persons ions and water will also diffuse into the dialysis fluid