Topic 12 - Role of the Kidneys in Homeostasis

Question 1

What is the function of the excretory system?

Answer 1

To remove cellular waste (CO2 + urea), filter blood and control water content in the body

Question 2

What is urea?

Answer 2

Excess amino acids broken down in the liver to form ammonia which bonds with CO2 in a process called deamination

Question 3

Why is deamination important?

Answer 3

Urea/Ammonia can be toxic to the body and is very soluble

Question 4

What is ultrafiltration?

Answer 4

When high-pressure blood is filtered of salts, water, urea, amino acids and glucose in the glomerulus and Bowman’s capsule

Question 5

What is selective reabsorption?

Answer 5

When useful substances are reabsorbed into the blood in the nephron

Question 6

What is excretion?

Answer 6

When water, urea and excess salt goes to the ureter (via the collecting duct) and then the bladder

Question 7

What makes up the excretory system? (8)

Answer 7

Aorta, Vena Cava, Renal Artery, Renal Vein, Kidney, Ureter, Bladder and Urethra

Question 8

What makes up the kidney?

Answer 8

Cortex, Pelvis, Medulla, Ureter, Renal Vein, Renal Artery

Question 9

What does the presence of urea in the blood or cells indicate?

Answer 9

Disease in the kidney

Question 10

What does the presence of glucose in the kidney indicate?

Answer 10

Diabetes

Question 11

What does the presence of blood or glucose or proteins in urine indicate?

Answer 11

Disease in the kidney

Question 12

Why is a blood thinner used in dialysis?

Answer 12

To prevent clotting

Question 13

What is the role of the dialyser?

Answer 13

Removes waste products from the blood by filtration

Question 14

What is dialysis fluid?

Answer 14

A fluid without salt and urea that flows in the opposite direction to the blood in the dialyser

Question 15

What is dialysis tubing?

Answer 15

Strands of tubing with a large surface area and a semi-permeable membrane to maximise osmosis/diffusion of salt, water and glucose from high to low concentration

Question 16

Why is a bubble trap used?

Answer 16

To prevent air from getting into the bloodstream

Question 17

What are the advantages of dialysis?

Answer 17

• Survival

- Allows for a wait

Question 18

What are the disadvantages of dialysis?

Answer 18

• Must be checked often
• Uncomfortable (12 hours a week)
• Disrupt social/work life
• Possibility of infection
• Rigid diet
• Impermanent

Question 19

What are the advantages of transplants?

Answer 19

• No toxin build-up
• No high blood pressure
• No blood clotting
• Survival

Question 20

What are the disadvantages of transplants?

Answer 20

• Expensive operation
• Immunosuppressants/Rejection
• Availability of donors/Right tissue type
• Infection/anaesthetic
• Payment for donors (ethical issues)

Question 21

What is the hormone that controls osmoregulation?

Answer 21

Anti-Diuretic Hormone

Question 22

From where is ADH released?

Answer 22

Pituitary gland

Question 23

What suppresses ADH production?

Answer 23

Alcohol (leading to dehydration)

Question 24

What increases ADH production?

Answer 24

Ecstasy (leading to overhydration)

Question 25

What happens when there is too much salt or sweating?

Answer 25

Low water content -> More ADH -> High volume reabsorbed by kidney -> Low volume, concentrated urine

Question 26

What happens when too much water is drunk?

Answer 26

High water content -> Less ADH -> Low volume reabsorbed by kidney -> High violume, dilute urine

Question 27

What is rejection?

Answer 27

When the body’s immune system attacks the foreign cells of a donated kidney -> immunosuppressants must be taken