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Excretion

Excretion is the removal of metabolic wastes from the body.

Any waste products from metabolic reactions are lost via excretion e.g. CO2 urea and H2O2.

DEFAECATION is not excretion it is egestion. This is because it is the removal of undigested bulk
(fibre) from the body. Faeces have not…

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The arrangement of liver cells in a lobule:




The liver is a dense organ with closely packed cells with multiple jobs. Its functions are:

To process nutrients from the digestive system.
To store glucose as glycogen.
To breakdown hormones.
To produce bile.
To excrete bile pigments.
To store vitamins and…

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Kidney nephron




In the glomerulus the blood plasma is put under pressure and filtrated through gaps in the squamous
endothelium called fenestrations or "little windows." This fluid then passes through the basement
membrane which is a collagen mesh. It then passes through podocytes which are slit like cell. These
stages…

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This selective re-absorption of ions, amino acids and glucose etc lowers the water potential in the
cells and increases the water potential and so water carries out osmosis and leaves the tubule. Any
unfiltrated proteins are reabsorbed by endocytosis.

Protein bound toxins are not filtered at the glomerulus and so…

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membrane (aka collagen mesh). Once i the urine their presence can be tested using gas
chromatography.

Gas chromatography works by vaporising the urine sample by dissolving it in another gas. It will then
be passed through a tube with an absorbant lining. The different substances will come out of the…

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Damage due to Obstruction of ureters,
obstruction of ureter, bladder or kidney.
bladder or urethra
Diabetes mellitus
Atherosclerosis,
reduces blood supply
to kidney
Symptoms/leads to Nephrons are progressively Little of no urine
destroyed leading to; produced
Reduced quantity of Accumulation of
urine nitrogenous waste in
Dilute urine blood
Dehydration Salt…

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Kidney transplants

The number of transplants is limited by the availiability of donors and the availability of good
tissue matches with the patient.

Tissue rejection is prevented with the use of drugs such as cyclosporine A which will damp the
immune response. They are also referred to as immunosuppressants. As…

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