GCE O Level Biology: Definitions of Keywords from Nutrition in Humans, Respiration and Excretion

Peristalsis

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Terms in this set (17)

Rhythmic wave-like contractions of the wall of the gut caused by alternate contractions of the circular and longitudinal muscles in the walls to help push food along the gut

Image: Peristalsis

Emulsification of fats

Occurs when bile breaks big blobs of fat into smaller fat droplets

Image: Emulsification of fats

Removal of undigested food from the body

Process of removing amino groups from excess amino acids and converted to urea, and occurs in the liver

Process of converting harmful substances into harmless substances

Cirrhosis of the liver

Disease where liver cells are destroyed and are replaced with fibrous tissue

Image: Cirrhosis of the liver

Oxidation of food substances with the release of energy in living cells

Aerobic respiration

Oxidation of food substances in living cells, in the presence of oxygen, with the release a large amount of energy. Carbon dioxide and water are released as waste products.

Image: Aerobic respiration

Anaerobic respiration

Breakdown of food substances in the absence of oxygen. Less energy is released than aerobic respiration.

Image: Anaerobic respiration

Amount of oxygen required to oxidise lactic acid produced in muscles during anaerobic respiration

Image: Oxygen debt