3a.5 - Kidneys Flashcards
1
Q
Describe the journey of blood to urine (6)
A
- Blood enters kidney in renal artery
- Kidneys filter blood
- Kidneys reabsorb useful substances to the blood
- ‘Clean’ blood leaves the kidney in the renal vein
- The mixture left in the kidney is urine
- The urine flows from the kidney to the bladder
2
Q
What are nephrons?
A
Filtration units in the kidneys
3
Q
What are the three stages of filtration in the kidneys?
A
- Ultrafiltration
- Reabsorption
- Release of wastes
4
Q
Describe the process of ultrafiltration (2)
A
- High pressure is built up which squeezes water, urea, ions and sugar out of the blood and into the Bowman’s capsule
- The membranes between the blood vessels and the Bowman’s capsule act like filters, so big molecules like proteins and blood cells are not squeezed out
5
Q
Describe the process of reabsorption (3)
A
- Sugar is reabsorbed by active transport
- Sufficient ions are reabsorbed through active transport
- Sufficient water is reabsorbed
6
Q
What happens if the kidney’s don’t work properly?
A
Waste substances build up in the blood and you lose the ability to control the levels of ions and water in the body
7
Q
What do dialysis machines do?
A
Filter the blood
8
Q
How does dialysis work? (4)
A
- Person’s blood flows alongside a selectively permeable barrier surrounded by dialysis fluid
- Dialysis fluid has the same concentration of dissolved ions and glucose healthy blood
- So dissolves ions and glucose aren’t lost
- Only waste substances, such as urea and excess ions and water diffuse across the barrier
9
Q
What are the disadvantages of a dialysis machine? (2)
A
- Has to be done 3 times a week for 3-4 hours
- Can cause blood clots and infections
10
Q
What are the measures taken to reduce the risk of the donated kidney being rejected? (2)
A
- Using a donor with a tissue type that closely matches the patient
- Patient treated with drugs that suppress the immune system
