B15 - Kidney Failure & Urine Samples Flashcards
What are some reasons for kidney failure?
- kidney infection, podocytes and tubules damaged
- Raised blood pressure damages epithelial cells in basement membrane of Bowman’s capsule.
- genetic conditions e.g. polycystic kidney disease. Tissues replaced by fluid-filled cysts.
What could blood in the urine indicate?
kidneys not filtering properly. Damaged basement membrane or podocytes not acting properly as filters . Large plasma proteins and blood gets into the filtrate.
Kidney failure can cause urea and mineral ions to build up in the body. Explain the effects of kidney failure. (3)
Loss of electrolyte balance:
- Na+,K+,Cl- can’t be secreted
- crates osmotic imbalance in tissues
- eventual death
Toxic urea in blood:
- poison cells
High blood pressure:
- kidneys help maintain blood pressure by maintaining water potential balance in blood.
- high BP cause strokes and heart problems.
Weakened bones:
- Calcium/phosphorus balance in blood lost.
Pain and stiffness:
- due to abnormal protein build up in blood.
Name the two types of dialysis.
Haemodialysis
Peritoneal dialysis
What does dialysis fluid contain? (3)
- normal glucose and plasma levels so no net movement out of blood
- normal mineral ion levels so excess diffuses out of blood into dialysis fluid.
- no urea, so urea leaves blood into fluid
- countercurrent flow between blood and fluid to maximise gas exchange.
Explain the process of haemodialysis
- blood leaves body through artery and into dialysis fluid.
- blood thinners containing herapin prevent blood clotting.
- blood passes through dialysis machine, removing waste.
- clean blood passes through bubble trap to remove bubbles in blood.
- clean blood returns to vein
What does the dialysis machine mimic?
- basement membrane
- has partially permeable dialysis membrane.
Explain the process of peritoneal dialysis.
- catheter introduces dialysis fluid into abdomen.
- peritoneum (lining of abdomen) acts as natural basement membrane.
- left for hours for dialysis to occur - urea and excess waste is removed from blood into tissue fluid, then across the peritoneal membrane into the dialysis fluid.
- fluid drained and discarded.
Explaint the difference between haemodialysis and peritoneal dialysis.
Haemodialysis
- use artificial dialysis machine as basement membrane
- usually done in hospital.
Peritoneal dialysis
- use natural peritoneum as basement membrane
- usually done at home, so patient can continue as normal
What are the disadvantages or haemodialysis? (3)
- Takes around 8 hours and must be repeated regularly.
- patients attached to machine several times a week for several hours.
- carefully manage diet (eat little salt and protein)
- monitor fluid intake to keep blood chemistry stable.
What is GFR? How is it measured?
GFR = Glomerular filtration rate
Blood test measures creatine in blood (breakdown product of muscle)
- gives an estimate (eGFR) in cm³min-¹
What needs to be considered when measuring GFR?
- GFR decreases with age, even if the person is very healthy
- men usually have more muscle mass and more creatine than women.
- a GFR below 60 indicates moderate-severe kidney disease ( normal GFRs don’t drop below 70)
In a kidney transplant, where is the new kidney usually placed?
- attached to blood vessels in the groin.
- ureter of new kidney inserted into bladder.
Why are immunosuppressant drugs used in kidney transplants? And what problems do they cause?
- suppress immune system and prevent rejection of new organ/recognised as ‘non-self’
Problem:
- patient doesn’t properly respond to disease/infection.
BUT this is outweighed by the advantages of a new kidney.
Why is a kidney transplant more ideal than dialysis?
- Dialysis = monitored diet and frequent sessions.
- long-term dialysis more expensive and has serious damaging side effects.
- kidney transplant free from these restrictions.
