Biology - Human Digestion and Nutrition

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Bile

Bile

Liquid produced by the liver and stored in the gall bladder. Emulsifies lipids and neutralises stomach acid

Duodenum

First part of the small intestine. Site of chemical digestion.

Peristalsis

Waves of muscle contraction in the oesophagus that allow food to pass down to the stomach from the mouth.

Villi

Small finger-like projections in small intestine. Increase the surface area for the absorption of the products of digestion. Covered with microvilli at their surface.

Vitamin C

Vitamin needed for maintenance of tissues, especially gums and skin. Also aids in resistance to infection. Deficiency called scurvy.

Large intestine

The colon, rectum and anus.

Iron

Mineral with several uses in the body, including as a component of haemoglobin in red blood cells.

Rectum

Second region of the large intestine where faeces are stored

Small intestine

Collective name for the duodenum and ileum.

Vitamin A

Vitamin important for vision in dim light. Deficiency causes night blindness.

Assimilation

Using the molecules produced by digestion for other purposes, e.g. for building new molecules, in the liver.

Lipase

Enzyme that digests lipids into fatty acids and glycerol.

Lipid

A biological molecule composed of fatty acids and glycerol. Functions in insulation and protection of the body and as an energy source.

Carbohydrates

A group of molecules that includes polysaccharides, such as starch and glycogen, and simple sugars, like glucose.

Absorption

Process that takes useful products of digestion from the digestive system into the blood or lymphatic system.

Digestion

Process of breaking large molecules into smaller ones using chemicals, such as enzymes and bile.

Egestion

The removal from the body of solid waste from the digestive system.

Pancreas

Large gland which secretes digestive enzymes, as well as the hormone insulin.

Fibre

Bulky material largely made up of cellulose from plant cell walls. Not digested by many animals, including humans.

Ileum

Second part of the small intestine. Site of the absorption of most of the useful products of digestion.

Lacteal

Lymph vessel in villi that absorbs the products of lipid digestion

Protease

An enzyme that breaks down proteins into amino acids.

Proteins

Type of biological molecule that is made from amino acids.

Amylase

Enzyme that is responsible for the break down of starch molecules.

Colon

First part of the large intestine. Site of water absorption into the blood stream.

Ingestion

The process of taking food into the body.

Oesophagus

The tube that carries food from the mouth to the stomach using peristalsis

Mechanical digestion

The process of physically breaking up food. Examples include chewing in the mouth and churning in the stomach.

Saliva

Fluid secreted in the mouth. Contains amylase.

Calcium

Mineral required to strengthen teeth and bones.