8. Excretion in humans

1. Core Content

• Excretion in Various Organs: Brief role of the following:

- the lungs;

- the kidneys and bladder;

- the liver;

- the alimentary canal (gut); and

- the skin.

The substances excreted by each and the origins of these substances.

• Urinary system

The structure of the:

- urinary system: position of kidneys, ureters, bladder, urethra.

- kidney: structure and functioning, removal of urea and excess water and salts, re-absorption of glucose and some salts.

- nephron: structure and functioning; ultra-filtration, reabsorption, tubular excretion, pH control, formation of urine

• Homeostatic control of water and salts: role of ADH and aldosterone: Dialysis and kidney transplants.

• Mention of diseases affecting kidney function, e.g. kidney stones, kidney failure due to overuse of some painkillers, effect of bilharzia infection.