Digestive System

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Digestion is the break-down of naturally occurring foodstuffs into diffusable form. It is also the change that makes food soluble and suitable for absorption through living membranes.

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Food cannot be used as such because it must be changed into a soluble and absorbable form. Only then can it pass through the wall of the gut into the blood and be distributed in the body.

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Enzymes are proteins that speed up chemical reactions in the body. They are specific, work best at a particular pH, and act best in a narrow temperature range of about 35°C to 40°C.

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Enzymes are proteins, so heating can destroy them. Each enzyme acts on only one kind of substance, called the substrate. Each enzyme works best at a particular pH. Each enzyme also works best in a nar…

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The alimentary canal is a muscular tube that starts at the mouth and ends at the anus. It is about 9 metres long and is highly coiled in some regions, especially in the small intestine.

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The food pathway is mouth, pharynx, oesophagus, stomach, small intestine, large intestine, rectum, and anus.

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Peristalsis is the wave of constrictions caused by the circular muscles of the gut that pushes food along the alimentary canal.

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The oesophagus is a muscular tube that conducts food from the throat to the stomach. It passes through the diaphragm close to the backbone and does not produce any digestive enzyme.