Kidney Failure

Question 1

Why might kidneys fail?

Answer 1

• Kidney infections where structures of podocytes and the tubules may be damaged or destroyed
• Raised blood pressure damaging epithelial cells and basement membrane of Bowman’s capsule
• Genetic conditions such as polycystic kidney disease where the healthy kidney tissue is replaced by fluid-filled cysts or damaged by pressure from cysts.

Question 2

Effects of kidney infections / high blood pressure?

Answer 2

• Protein in urine
• Blood in urine

Question 3

Protein in urine cause:

Answer 3

• Basement membrane or podocytes of Bowman’s capsule are damaged, they no longer act as filters and large plasma proteins pass into the filtrate and are passed out of the urine.

Question 4

Blood in urine caused:

Answer 4

• Basement membrane or podocytes of Bowman’s capsule are damaged, they no longer act as filters and large plasma proteins pass into the filtrate and are passed out of the urine.

Question 5

If kidneys fail completely, concentrations of urea and mineral ions build up in the body. This leads to:

Answer 5

• Loss of electrolyte balance
• Build-up of toxic urea in the blood
• High blood pressure
• Weakened bones
• Pain and stiffness in joints
• Anaemia

Question 6

Loss of electrolyte balance

Answer 6

• Body cannot excrete excess sodium, potassium and chloride ions.
• Osmotic imbalances in tissues
• Death

Question 7

Build-up of toxic urea in the blood

Answer 7

• Body cannot get rid of urea and it can poison the cells

Question 8

High blood pressure

Answer 8

• Kidneys play an important role in controlling the blood pressure by maintaining the water balance of the blood
• Blood pressure increases and this can cause a range of health problems including heart problems and strokes

Question 9

Weakened bones:

Answer 9

• Calcium / phosphorus balance in blood lost

Question 10

Pain and stiffness in joints:

Answer 10

• Abnormal proteins build up in the blood

Question 11

Anaemia

Answer 11

• Kidneys are involved in the production of a hormone called erythropoietin that stimulates formation of red blood cells
• When kidneys fail it can reduce production of red blood cells causing tiredness and lethargy

Question 12

Measuring glomerular filtration rate (GFR):

Answer 12

• Indicates kidney disease
• Blood test measures creatinine levels in blood.
• Creatinine is a breakdown product of muscles and it is used to give an estimated GFR (eGFR)
• Units are cm^3/min

Question 13

If levels of creatinine in blood go up:

Answer 13

• Kidneys are not working properly

Question 14

Other factors to take into account when measuring GFR?

Answer 14

• GFR decreases steadily with age even if health
• Men usually have more muscle mass than women

Question 15

GFR below 60 for 3 months:

Answer 15

• Indicates moderate - severe kidney disease

Question 16

GFR below 15:

Answer 16

• Kidney failure
• Filter so little blood that they are ineffective

Question 17

Type types of treatment for kidney failure:

Answer 17

• Renal dialysis
• Transplant

Question 18

Two main types of dialysis:

Answer 18

• Haemodialysis
• Peritoneal dialysis

Question 19

Haemodialysis:

Answer 19

• Dialysis machine
• Blood leaves patient’s body from an artery and flows into the dialysis machine, where it flows between partially permeable dialysis membranes.
• Membranes mimic the basement membrane of the Bowman’s capsule.
• On the other side of the membrane is dialysis fluid.
• Patients lose excess urea and mineral ions that build up in blood.
• Countercurrent exchange system maximises exchange taking place

Question 20

Haemodialysis –> prevention of blood clotting

Answer 20

Blood thinners in dialysis machine

Question 21

Haemodialysis –> prevent bubbles forming

Answer 21

Clean blood flows through bubble trap to get rid of bubbles.

Question 22

How is the loss of glucose and needed molecules prevented in haemodialysis?

Answer 22

• The dialysis fluid contains normal plasma levels of glucose to ensure there is no net movement out of blood.
• Same for mineral ions to restore electrolyte ballance

Question 23

How is the loss of urea ensured in haemodialysis?

Answer 23

• No urea in dialysis fluid so very steep concentration gradient.

Question 24

What does haemodialysis depend on?

Answer 24

• Diffusion down concentration gradient.

Question 25

Life of someone on haemodialysis?

Answer 25

- Eight hours many times a week. - Manage diets --> eat few proteins and salt - Only time they can eat and drink anything is the start of the dialysis process.

Question 26

Peritoneal dialysis?

Answer 26

- Inside the body - Makes use of natural dialysis membranes formed by lining of the abdomen (the peritoneum). - Dialysis fluid is introduced to abdomen using catheter. - Fluid is then drained off and discarded, leaving blood balanced again.

Question 27

Transplant: how

Answer 27

- Blood vessels are joined and the ureter of the new kidney is inserted into the bladder.

Question 28

Risks of transplant:

Answer 28

- Rejection --> antigens on the donor organ differ from the antigens on the cells of the recipient and the immune system is likely to recognise this. - Don't last forever (9-10 years) --> return to dialysis until another suitable kidney is found

Question 29

How to reduce risk of rejection:

Answer 29

- Match between antigens of donor an recipient as close as possible. - Donor kidney can be used with a 'tissue type' very similar to recipient - Immunosuppressant drugs for rest of lives --> need for close match is becoming less important

Question 30

Disadvantage of immunosuppressants:

Answer 30

- Can not respond effectively to infectious diseases - Take great care if become ill

Question 31

Comparison of dialysis and transplant:

Answer 31

- Dialysis more readily available - But, monitor diet - Dialysis more expensive and can eventually damage body - Transplant has few restrictions

Question 32

Main source of transplants:

Answer 32

- Die suddenly --> road accidents, heart attacks, strokes - Relatives can give consent if people don't carry an organ donor card or are not registered online.

Question 33

Why is there a shortage of transplants?

Answer 33

- People do not donate - Cars are safer

Question 34

How is the lack of donors combatted?

Answer 34

- Family donations - Embryonic kidney tissue made from stem cells --> grow kidneys with matching antigens