Topic 7

Question 1

Water balance

Answer 1

Regulation of water levels in blood and body fluids, cells and molecules can function properly.

Question 2

Urination

Answer 2

The removal of excess water, ions and urea from the body via the kidneys

Question 3

Urine

Answer 3

Mixture of water, urea and excess minerals that is filtered from the blood by the kidneys and excreted

Question 4

Filtration

Answer 4

The separation of specific substances such as urea, water and minerals which are filtered from the blood by the kidneys

Question 5

Selective reabsorption

Answer 5

The kidneys reabsorb key molecules such as glucose and some ions and water depending on how concentrated the blood is

Question 6

How kidneys contribute to balancing water levels

Answer 6

Kidneys control the concentration of urine that is excreted and can change the levels of water that is filtered, so that water levels are maintained

Question 7

Nephron

Answer 7

Microscopic tubules of the kidney that act as functional units, nephrons are the site of filtration in kidneys

Question 8

Collecting duct

Answer 8

The portion of the nephron where water reabsorption is regulated via anti-diuretic hormone, several nephrons empty into each collecting duct and this is the final region through which urine must pass on its way to the ureter

Question 9

Negative feedback cycle

Answer 9

Where a change in something brings about a process that causes the opposite effect, keeping levels constant

Question 10

ADH

Answer 10

Anti-diuretic hormone which causes more water to be reabsorbed back into the blood from the kidneys if blood water levels are low\

Question 11

Kidney tubules

Answer 11

Where ADH acts to increase the permeability so that more water is reabsorbed back into the blood

Question 12

Permeability

Answer 12

The ability of particles to move through a membrane

Question 13

Pituitary gland

Answer 13

The master gland where ADH is released

Question 14

Concentrated blood negative feedback

Answer 14

If water levels in the blood become too low, ADH is released to counteract the change

Question 15

Dilute blood negative feedback

Answer 15

If water levels in the blood become too high, ADH is inhibited to counteract the change

Question 16

Difficulties regarding water balance

Answer 16

There is no control over water, ion or urea loss by the lungs or skin

Question 17

Kidney transplant

Answer 17

The transfer of a healthy kidney by a donor to a person with kidney failure, depends on donor lists and there is risk of rejection

Question 18

Dialysis

Answer 18

A procedure to remove waste products and excess fluid from the blood in individuals with kidney failure

Question 19

Counter-current system in dialysis

Answer 19

Ensures that a diffusion gradient for urea is always maintained, otherwise urea could be reabsorbed

Question 20

Hemodialysis

Answer 20

Uses a machine and filter to remove waste products and excess water from the blood

Question 21

Peritoneal dialysis

Answer 21

Uses a catheter and a fluid that is placed in the abdominal cavity to remove waste products and excess water from the blood

Question 22

Issues of transplants and dialysis

Answer 22

Transplants can be rejected by the body unless treated with medication and dialysis affects lifestyle or can lead to diseases if complications occur

Question 23

Dialysis fluid concentrations

Answer 23

Dialysis fluid must contain similar concentrations to blood plasma to prevent cells bursting/shrinking and to maintain a concentration gradient