Module 5: Kidney Failure

Question 1

What are the three main causes of kidney failure ?

make 1 point about how these causes effect structures of the kidney and lead to failure

Answer 1

infections-can damage or destroy the structure of podocytes and tubules
raised blood pressure-can damage structure of epithelial cells and the basement membrane of the Bowman’s capsule
genetic conditions-eg polycystic kidney disease which is where healthy kidney tissue replaced by fluid filled cysts/damaged by pressure from cysts

Question 2

If the kidneys are infected or affected by high blood pressure , this can cause ..

2 things (explain point 1)

Answer 2

protein in urine-if podocytes/membranes are damaged they will no longer be able to act as filters , allowing large plasma proteins to pass into filtrate and be passed out in urine

blood in urine

Question 3

If the kidneys fail , the concentration of what two substances will build up in the body?

Answer 3

urea and mineral ions

Question 4

List the first three effects of urea/mineral ion build up on the body

Answer 4

loss of electrolyte balance-if kidneys fail the body can’t excrete excess ions which causes osmotic imbalance in tissues

build up of urea in blood-can poison bodily cells

high blood pressure-kidneys play important role in controlling blood pressure by maintaining water balance of blood so if they fail blood pressure will increase

Question 5

List the final three effects of urea/mineral ion build up on the body

Answer 5

weakened bones-due to calcium/phosphorus imbalance in the blood

pain and stiffness in joints-due to build up of abnormal proteins in the blood

anaemia-kidneys are involved in production of hormone called erythroprotein that stimulates RBC formation so if kidneys fail this can reduce production of RBCs

Question 6

What is one process that kidney failure almost always effects the rate of?

Answer 6

the rate at which blood is filtered in the Bowman’s capsule

Question 7

What rate is widely used as a measure to indicate kidney disease?

Answer 7

Glomerular filtration rate (GFR)

Question 8

Describe how GFR is used to indicate kidney disease

make 3 points

Answer 8

-rate of filtration not measured directly
-a blood test is taken to measure level of creatinine in blood
-if levels increase its a signal that the kidneys aren’t working properly

Question 9

What is creatinine?

Answer 9

a breakdown product of muscles

Question 10

What is renal dialysis?

Answer 10

when the function of the kidneys is carried out artificially

Question 11

What are the 2 main types of dialysis?

Answer 11

haemodialysis
peritoneal dialysis

Question 12

Make 4 points about how haemodialysis works

Answer 12

-involves use of a dialysis machine
-blood leaves patient from an artery and flows into the machine where it flows between partially permeable dialysis membranes
-these membranes mimic the basement membrane of the Bowman’s capsule
-on the other side of the membranes is dialysis fluid

Question 13

Describe the composition of dialysis fluid and why it has this composition

3 points

Answer 13

contains normal plasma levels of glucose-ensures there is no net movement of glucose out of the blood
contains normal plasma levels of mineral ions-ensures any excess ions move out by diffusion down their concentration gradient into dialysis fluid to restore electrolyte balance of blood
contains no urea-ensures theres a steep concentration gradient between blood and fluid so much of urea leaves blood

Question 14

Why does the blood and dialysis fluid flow in opposite directions?

Answer 14

to maintain a counter current exchange system to maximise exchange

Question 15

Make 4 points about how peritoneal dialysis works

Answer 15

-done inside the body by using dialysis membranes formed by lining of the abdomen
-dialysis fluid is introduced into abdomen using a catheter
-catheter left for several hours so that urea and excess mineral ions can pass out of blood capillaries into tissue fluid and then across peritoneal membranes into dialysis fluid
-the fluid is then drained off and discarded , leaving blood balanced again

Question 16

What is the main risk associated with a kidney transplant?

make 3 points about this

Answer 16

the risk of rejection-the antigens on the donor organ will differ from those on the cells of the recipient
the recipients immune system is likely to recognise these non-self antigens
this may result in the destruction of the donated kidney

Question 17

Give 2 ways that the risk of rejections can be reduced

Answer 17

match the antigens of the donor and recipient as closely as possible

give the recipient immunosuppressant drugs for the rest of their life

Question 18

What is a negative side effect of giving a patient immunosuppressant drugs

Answer 18

these drugs will prevent the patient responding effectively to infectious diseases , therefore they must be extremely careful if they become ill

Question 19

Make 3 points comparing the effectiveness of dialysis treatment and kidney transplants

Answer 19

-dialysis is much more readily available than donor organs
-LT use of dialysis is far more expensive and can eventually lead to damaging the body
-dialysis requires dietary monitoring and regular sessions on the machine whereas transplant can be a much faster and less time committing process