B3 - Kidney

All you must know about the Kidney for B3 AQA GCSE Biology Higher

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  • Created by: Steven
  • Created on: 17-04-12 20:25

The Human Kidney

An essential organ! Without it or artificial blood cleaning you would die..

They filter our blood, excreting unwanted substances and reabsorbing useful substances.

Your Renal Artery brings dirty blood to the kidney with Urea and other substances in solution.

Your Renal Vein carries clean filtered blood away from the Kidney back towards the heart.

The unwanted substances are all passed through the ureter into the bladder where Urine is stored.

Your urethra then excretes the urine when you go to the toilet expelling all of the toxins your kidney filtered out.

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Filtering of the blood:

3 Stages:

1) Dirty blood enters kidney and is filtered
2) Blood is cleaned and filtered etc.
3) Some substances are reabsorbed and some are taken to the bladder

What is Reabsorbed then?

- All the sugar, the dissolved ions we need and as much water as we need
(The Sugar and Ions may be resabosrbed by Active Transport against the concentration gradient)
(Protein is never filtered out as it is too large a molecule to be filtered)

What is "Released to the Bladder?"

- Urea
- Excess Ions
- Excess Water 

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Unhealthy Kidney's!

Some people suffer from a variety of diseases or have kidney failure leading to an issue or a complete infunction of the kidney or kidney's. 

  • A dialysis machine does exactly what your kidney's do - but it is an expensive and it isn't a nice process - it take hours and you can't move very much. It must also be carried out regularly as your body is always making more toxins
  • Your blood passes out of your body, into a dialysis machine and the blood flows between a Partially Permeable Membrane - The Dialysis fluid contains the same concentration of useful substances as the patient's blood - this means they are not filtered out removing the need for reabsorbption. Urea and excess ions and water are filtered out though

Dialysis restores the blood to the correct concentration's and removes the toxins in the blood - until it needs to be done again!

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Kidney Transplant's!

For most, a transplant is better than dialysis! - It means no more restrictions due to the machines and life is returned as much as possible to normal!

- A donor kidney must be found, often from a newly dead person so that the tissue is fresh. - There must be a very good tissue match to reduce the risk of rejection.

- As the immune system is likely to reject the new kideny, measures are taken to prevent this;
 1) The patient's bone marrow is Radiation Treated to stop White Blood Cell production
2) The recipient will be kept in sterule conditions after the transplant to reduce the risk of infection
3) The patient will take immuno-suppressant drugs for life

The new kidney is placed in the groin and the new kidney is attached to all of the correct arteries, veins and tubes with the old kidney left and it has it's tubes cut or even just left. 

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