15.8 Kidney Failure Flashcards
What are some causes for kidney failure?
1) Kidney infections
2) High blood pressure
3) Polycystic kidney disease
How can kidney infections lead to kidney failure?
- Kidney infections can cause inflammation (swelling) of the kidneys, which damage cells.
- This interferes with the filtering in Bowman’s capsule where the structures of podocytes may be damaged or destroyed.
- This also interferes with the reabsorption if the structures of the tubules also damaged/destroyed.
How can high blood pressure lead to kidney failure?
Raised blood pressure can damage the structure of the epithelial cells and basement membrane of the Bowman’s capsule.
What is polycystic kidney disease and how can it lead to kidney failure?
Polycystic kidney disease is where the healthy kidney tissue is replaced by fluid-filled cysts or damaged by pressure from cysts.
What effects can HIGH BLOOD PRESSURE have on the kidney?
1) PROTEINS IN URINE- if the basement membrane or podocytes are damaged, they no longer act as filters and large plasma proteins can pass into the filtrate and passed out in the urine.
2) BLOOD IN URINE- another symptom that the filtering process is no longer working.
What are the effects of KIDNEY FAILURE?
1) LOSS OF ELECTROLYTE BALANCE- if the kidneys fail, the body cannot excrete excess sodium, potassium and chloride ions. This causes osmotic imbalances in the tissues and eventual death.
2) BUILD UP OF TOXIC UREA IN THE BLOOD- If the kidneys fail, the body cannot get rid of excess urea and it can poison the cells.
3) HIGH BLOOD PRESSURE- The kidneys play an important role in controlling the blood pressure by maintaining the water balance of the blood. If the kidneys fail, the blood pressure increases and this can cause a range of health problems including heart problems and strokes.
4) ANEMIA- The kidneys are involved in the production of the hormone erythropoietin which stimulates the formation of red blood cells. When the kidneys fail, it can reduce production of red blood cells causing tiredness and lethargy.
5) PAIN AND STIFFNESS IN JOINTS AND BONES- as abnormal proteins build up in the blood.
How can kidney failure be detected?
By measuring the glomerular filtrate rate
What is the glomerular filtrate rate?
The rate at which blood is filtered from the glomerulus into the Bowman’s capsule.
How is the GFR measured?
A blood test measures the level of creatinine in the blood. Creatinine is a breakdown product of muscles and it gives an estimated glomerular filtration rate. (eGFR)
What are the two types of dialysis?
1) Haemodialysis
2) Peritoneal dialysis
What occurs in haemodialysis?
1) Blood leaves the patient’s body from an artery and flows into the dialysis machine, where it flows between partially permeable dialysis membranes.
2) These membranes mimic the basement membrane of the Bowman’s capsule.
3) On the other side of the membrane is the dialysis fluid.
4) During dialysis it is vital that patients lose excess urea and mineral ions that have built up in the blood, which diffuse down the concentration gradient.
What key features does the dialysis fluid have to ensure efficiency?
1) The dialysis fluid contains normal plasma levels of glucose to ensure there is no net movement of glucose out of the blood.
2) It also contains normal plasma levels of mineral ions, so any excess ions in the blood move out by diffusion into the dialysis fluid, thus restoring the correct electrolyte balance of the blood.
3) The dialysis fluid contains no urea meaning there is a very steep concentration from the blood to the fluid, and as a result much of the urea leaves the blood.
In which direction do the blood and dialysis fluid flow? Why?
The blood and dialysis fluid flow in opposite directions to maintain a countercurrent exchange system and maximise the exchange that takes place.
What occurs in peritoneal dialysis?
- Peritoneal dialysis is done inside the body- it makes use of the natural dialysis membranes formed by the lining of the abdomen- peritoneoum.
- The dialysis fluid is introduced into the abdomen using a catheter.
- It is left for several hours for dialysis to take place across the peritoneal membranes, so that urea and excess mineral ions pass out of the blood capillaries, into the tissue fluid, and out across the peritoneal membrane into the dialysis fluid.
- The fluid is then drained off and discarded, leaving the blood balanced.
What occurs during kidney transplant?
- A single healthy kidney from a donor is placed within the body.
- The blood vessels are joined and the ureter of the new kidney is inserted into the bladder.
