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How does dialysis work?
Medicine & HealthLesson on requestFree to read
Quick answer
Dialysis works by filtering waste and excess fluid from the blood when the kidneys can't. Blood is passed across a special membrane with cleansing fluid on the other side, and waste crosses over by diffusion — doing the kidney's job artificially.
Step by step
- Healthy kidneys filter waste and extra water from blood; dialysis replaces that when they fail.
- In hemodialysis, blood flows through a machine past a semi-permeable membrane.
- Waste molecules diffuse from the blood into a cleansing fluid (dialysate) and are carried away.
- Excess fluid is also drawn off, and the cleaned blood returns to the body.
- Peritoneal dialysis instead uses the lining of the abdomen as the natural filter.
People also ask
Why do people need dialysis?
When the kidneys lose most of their function (kidney failure), waste and fluid build up dangerously. Dialysis removes them artificially to keep the person well.
How does waste actually leave the blood?
By diffusion: waste is concentrated in the blood and nearly absent in the cleansing fluid, so it naturally moves across the membrane from high to low concentration.
Is dialysis a cure?
No — it replaces lost kidney function but doesn't heal the kidneys. It's ongoing treatment unless the person receives a kidney transplant.