Removing waste

Question 1

Water maintenance system

Answer 1

If the blood has too much water/ diluted = water moves into cells by osmosis
If the blood has too little water/ concentrated = water moves out of cells into blood by osmosis

Question 2

How is water lost in the body?

Answer 2

Water vapour lost when exhaled
Sweating through the skin
Urine

Question 3

What do the kidneys remove?

Answer 3

Urea
Excess ions
Water

Question 4

How do kidneys work?

Answer 4

Blood containing urea enters kidney through artery
Kidney removes urea, excess ions and water in the blood
Cleaner blood leaves kidney
This leaves kidney as urine and stored in bladder then released
So blood has no urea

Question 5

How do kidneys adjust small molecule level in blood?

Answer 5

Enter into kidney through artery
Blood through capillaries
Kidneys filter small molecules out (urea, ions, water, glucose)
Passes into a tube
Where ALL glucose, some ions and some water reabsorbed into blood
What isn’t absorbed eg some ions and water leave as urine

Question 6

What happens if we have excess amino acids in blood?

Answer 6

This happens if we eat too much protein
So it’s been digested and in our blood
So broken down by liver to create ammonia
But this is toxic so liver convert it to urea which is excreted by kidneys

Question 7

Deamination

Answer 7

Breaking down excess amino acids into ammonia then converted to urea

Question 8

What happens if water levels in blood falls?

Answer 8

Pituitary gland releases hormone ADH into blood stream
Which travels to kidneys
And causes the tubes in kidneys to become more permeable to water
Therefore more passes from the kidney into the blood
So less urine produced

Question 9

What happens if water levels in blood become too low (=concentration blood)?

Answer 9

Pituitary gland release ADH in blood to the kidneys
So kidney tubes become more permeable to water
So more water absorbed into tubules
So more water reabsorbed back into blood = less urine as more concentration

Question 10

Kidney failure

Answer 10

Blood contains higher concentration of water, ions and urea than it should
Because the kidneys aren’t reabsorbing this

Question 11

Dialysis

Answer 11

Patient hooked up to a machine
Blood passes over a semi permeable membrane
So ions and water to pass through into dialysis fluid but NOT UREA as proteins can’t fit through

Question 12

What does dialysis fluid contain?

Answer 12

Normal concentration of water and ions
To remain a small concentration gradient so not all water and ions leave
But has NO UREA so ALL urea in patient diffuses through = high concentration gradient

Question 13

Why is dialysis fluid always replaced?

Answer 13

So large concentration gradient for urea = will diffuse through
So some water and ions will pass through from blood into machine = return normal

Question 14

Kidney transplant

Answer 14

Adding a healthy kidney to the patient

Question 15

Cons of kidney transplant

Answer 15

Shortage of kidney donors
Expensive initially
Anti rejection drugs for rest of life to avoid rejection

Question 16

Pros of kidney transplant

Answer 16

Allows patient to lead normal life
Only expensive initially, an investment

Question 17

Cons of dialysis

Answer 17

Requires frequent treatments and controlled diets
Expensive in the long run

Question 18

Pros of dialysis

Answer 18

No shortage of dialysis machines

Question 19

What happens if blood becomes too dilute (too much water)?

Answer 19

Stops producing ADH so less water absorbed into blood by kidney and more urine produced = more urine