B3 - Kidneys Flashcards
What are the 3 phases of filtration in the kidneys?
Ultrafiltration
Reabsorption
Release of wastes
What are nephrons?
The filtration units in the kidneys
Describe the process of ultrafiltration
A high pressure is built up that squeezes the water, ions, urea and sugar out of the blood and into the Bowman’s capsule
The membranes between the blood vessels and the Bowman’s capsule act like filters so that larger molecules like protein and blood cells can’t get through
Describe the process of reabsorption
As the liquid flows along the nephron, useful substances are absorbed back into the blood
These are: all sugar (active transport), required ions (active transport) and required water
Describe the release of wastes
The remaining substances continue out of the nephron, into the ureter and down to the bladder as urine
What happens if the kidneys are not functional?
Waste substances will build up in the blood and there will not control of the levels of ions and water
What are the 2 ways that people with kidney failure can be treated?
Dialysis machine doing the job of a kidney
Kidney transplant
Describe how a kidney dialysis machine works
The blood goes into the machine and the waste products diffuse into the dialysis fluid
The exchange surface is not permeable by the larger molecules
What is the dialysis fluid made from and why?
It is a fluid that has the same concentration of ions and glucose as healthy blood so that ions and glucose are not lost from the blood
What are the 2 disadvantages of kidney dialysis?
There is a 3 hour session of dialysis 3 times a week
Dialysis can cause blood clots and infections
Why are kidney transplants sometimes rejected?
The foreign antigens of the kidneys are attacked by the antibodies of the patient (their immune system is rejecting it)
What are the 2 ways that we overcome kidney transplant rejection?
A donor with a similar tissue type to the patient is chosen (tissue type is based on antigens)
Drugs are given that suppress the immune system so that the kidneys are not attacked
