- Diuresis (increase in urine output)
Diuretics are chemicals that increase output of urine:
- caffeine
- alcohol
- very high levels of blood glucose or blood urea
- Kidney failure
Kidney failure occurs when the kidneys stop working.
What causes kidney failure?
- an injury to the kidneys, including kidney stones
- streptococcus bacteria can cause an infection
- excessive use of certain drugs
What are kidney stones
Insoluble stones called renal calculi
Caused by:
- too much calcium in the diet
- a decrease in water intake
- abnormally alkaline or acidic urine
Types of trauma
- Blunt forced trauma is a direct blow to the abdomen, best indicator of a blunt kidney injury is blood in the urine
- A penetrating force trauma is when the skin is broken or could be more severe, eg a gunshot
Kidney transplants
The long term solution to kidney failure is kidney transplants
Main functions of the kidneys
The main function of the kidneys is to maintain homeostasis by controlling the composition and volume of body fluids. The kidneys:
- Excrete nitrogenous waste in the form of urea and small amounts of uric acid and creatinine to prevent a build up of these toxic substances
- With the help of the skin, are responsible for osmoregulation
- Help maintain the pH of body fluids by excreting more or less hydrogen ions
- Help to maintain the balance of ions in the body
Dialysis
Kidney failure occurs when the kidneys stop working properly. The short term solution to kidney failure is to cleanse the blood artificially by means of dialysis, using a kidney machine
What is dialysis
Is the movement of molecules between two solutions of different compositions down their concentration gradients
How does a kidney machine work
- blood from an artery in the patients arm flows into a dialyser, and then back into the vein in the arm
- in the dialyser blood circulates through fine tubes made of selectively permeable membranes
- an important difference is that it has no nitrogenous waste
- waste substances are found in the blood plasma but not in the dialysis solution. These waste products will therefore diffuse from the blood plasma down a concentration gradient
- the dialysis solution is continuously replaced to keep the concentration gradients favourable
Disadvantages of dialysis
- time consuming
- very expensive
- limits fluid intake
- connect remove potassium and phosphates, which can build up and be life threatening
- patient may feel ill
- can lead to bleeding problems
How are the kidneys procured for kidney transplants
Many recipients never get the kidney they need because:
- the donor does not comply with the strict criteria
- the tissue and blood type of the donor and recipient are not compatible
- no one has signed agreement for the donor kidney to be transplanted
- the recipient has not had end-stage organ failure
