B12

Question 1

If the kidneys don’t work properly

Answer 1

Waste substances build up in the blood and you lose your ability to control the levels of ions and water in your body.

Question 2

Deamination

Answer 2

The liver removes the amino groupfrom the amino acids

Question 3

Explain how and why urea is removed from the body

Answer 3

• proteins (and the amino acids that they are broken into) can’t be stored by the body- so anh excess amino acids are converted into fats and carbs, which can be stored.
• This occurs in the liver and involves a process called DEAMINATION
• ammonia is produced as a waste product from this
• ammonia is toxic and is converted to urea in the liver and then transported to kidneys where us us filtered out and excreted from the body in urine

Question 4

Give the several organs that are important in removing waster from body

Answer 4

• LUNGS- removes carbon dioxide, a product of respiration
• LIVER- converts excess protein (amino acids) into urea
• SKIN- provides surface for small amounts of water and salt to move out of the body.
• KIDNEYS- removes unwanted substances such as urea, excess water and salt.
• bladder and urethra

Question 5

Explain how ions are relased from the body in urine and why?

Answer 5

• ions like sodium are taken into body in food, then absorbed into the blood
• if the ion or water content of the body is wrong, this couod upset balance between ions and water, meaning too much or little water us drawn into cells by osmosis. This can damaged cells.
• some jons are lost in sweat, however, this amount is not regulated, so the right balancd of ions in the bodu must be maintained by the kidneys.
• the rught amount is reabsorbed into the blood after filtration and the rest is removed form the body in urine.

Question 6

Explain how and why water is removed from the body in urine

Answer 6

• the body has to contantly balance the water coming in against the water going out.
• we lose water from then skin in sweat and from the lungs when breathing out
• we can’t control how much we lose in these ways, so the amount of water is balanced by the amount we consume and the amount removed by the kidneys in urine.

Question 7

Explain how carbon dioxide is removed from the body in urine

Answer 7

-The carbon dioxide produced by the body cells during respiration must be removed because dissolved carbon dioxide produces an acidic
solution.
-This would affect enzymes working in cells
-The carbon dioxide diffuses out of the cells into your blood down a concentration gradient. -It diffuses from the blood into the air in the alveoli of your lungs.
- This air containing the excreted carbon dioxide is removed from your body when you exhale.
-As a side effect of exhalation, you lose
water when the moist air from inside your lungs is forced out of the body.

Question 8

The kidneys make urine by taking waste produts

Answer 8

Out of your blood.

Question 9

How are waste products got out of your blood

Answer 9

They are fiktered out as it passes through the kidneys called filtration

Question 10

Useful substances like glucose, some ions and the right amount of water are fhen absorbed back into the blood. This is called

Answer 10

Selective reabsorption

Question 11

How do your kidneys work

Answer 11

• glucose, salts, urea and water all move put of your nlood and into the kidney.
• also, blood cells and large proteins are too big go pass through the filtering process
• any useful substances like glucose, some ions and the right amount of water will be reabsorbed back into the blood theough selective reabsorption.
• anything that is not needed is removed in the urine

Question 12

The concentration of urine is controlled by a hormone called

Answer 12

ADH (anti-diuretic hormone)

Question 13

ADH is released into the bloodstream by the

Answer 13

Pituitary gland

Question 14

The whole process of eater content regulation is contorlle by a

Answer 14

Negative feedback cycle

Question 15

If water content increases-

Answer 15

• a receptor in brain detects that water is too high
• the coordination centre in brain recieves the info and coordinates a response
• the pituitary goand releases less ADH, so less water is reabsorbed from the kidney tubules

Question 16

The brain monitors the water content of the blood and instructs the pituitary gland to release

Answer 16

ADH

Question 17

If water content is too high/low, less or more ADH is released

Answer 17

If too high, less ADH is released
If too low, more ADH is released

Question 18

If water content decreases…

Answer 18

• a receptor in brain detects that the water content is too low
• the coordination centre in rhe brain recieves the infor and coordinates a response
• the pituitary gland releases more ADH, so more water is reabsorbed from the kidney tubules

Question 19

What are two problems with the kidneys

Answer 19

Kidney stones:
- high salt and minerals in your diet can lead to stones precipitating out
- extermely painful
- have to be excereted from the body in the urine
RENAL DAMAGE/failure:
- the kidney is no longer able to filter the blood effectively

Question 20

Dialysis

Answer 20

The function of the kidney is carried out artificially

Question 21

Kidney transplants: facts and figures

Answer 21

• healthy kidneys are usually transplanted from people who have died suddenly
• people who have died must be on the organ donor reguster or carry a donor card.
• kidneys can be transpoanted from peopoe who are aluve nut there is s risk to the person donating
• also the donor kidney csn be rejected by patient’s immune system. It can happen but patient is treated with drugs to try to stop it
• transplants are CHEAPER than dialysis and they can put an end to the hours patients have to spend on dialysis. However, there is a long waiting lists for kidneys

Question 22

Why does dialysis have to be done regularly

Answer 22

Because the concentrations of dissolved substances in the blood must be kept st normal levels, to remove waster subtsances.

Question 23

Explain how dialysis occurs

Answer 23

• in a dialysis machine the person’s blood flows between partially permeable membranes,
  surrounded by dialysis fluid.
• the dialysis fluid has the same conc. of dissolved ions and glucose as healthy blood.
• this means thag useful dissolved ions and glucose won’t be lost from the blood during dialysis. (Only waste substances like urea and excess ions/water diffuse accrods the barrier.

Question 24

Ads and dis of Dialysis

Answer 24

Dis:
- each session takes 3-4 hours and 3-4 sessions a week
- may cause blood clots, infections.
-not a pleasant experience and it very expensive
ADS:
- dialysis buys a patient with kidney failure valuable time unti la donor organ is found

Question 25

Explain why kidney failure is a threat to life?

Answer 25

Toxins like urea build uo in the body and balance of water and mineral ions is not maintainted, which causes cell damage.

Question 26

In what process does dialysis depend

Answer 26

Diffusion, down a concentration gradient

Question 27

Explain why people with kidney failure have to control their intake of protein and salt

Answer 27

-People with kidney failure cannot remove excess mineral ions such as
salt
-or get rid of urea produced by the breakdown of excess amino acids
from proteins,
-so they have to limit intake to keep levels in body as low as possible to
remain feeling well between dialysis sessions.