Chapter 8: Excretion in humans (dialysis and kidney)

Question 1

Why are kidneys important?

Answer 1

It excretes metabolic waste products such as urea, excess water and mineral salts.

Question 2

What happens if the kidneys fail?

Answer 2

There will be an accumulation of excretory products in the blood

Question 3

What are the features of the dialysis machine?

Answer 3

1. Dialysis fluid contains the same concentration of essential substances as healthy blood ( like glucose, amino acids and mineral salts)
2. Dialysis fluid does not contain metabolic waste products
3. Tubing in the dialysis machine is long, narrow and coiled
4. The directions of blood flow is opposite to the flow of dialysis fluid

Question 4

Why does dialysis fluid contain the same concentration of essential substances as healthy blood?

Answer 4

To ensure essential substances do not diffuse out of the blood into the dialysis fluid, and can also allow patients that lack these substances to diffuse into their blood.

Question 5

Why does dialysis fluid not contain metabolic waste products?

Answer 5

It will set up a concentration gradient to allow waste products to diffuse out of the blood into the dialysis fluid.

Question 6

Why is the tubing in the dialysis machine long, narrow and coiled?

Answer 6

Increasing surface area to volume ratio, speeding up the rate of exchange of substances

Question 7

Why is the directions of blood flow opposite of the flow of dialysis fluid?

Answer 7

It maintains the concentration gradient between blood and the dialysis fluid.