The digestive system

Ingestion

Taking food into the body

Digestion

Breakdown of complex food substances into smaller soluble food substances

Absorption

Digested food is absorbed into the blood by diffusion and active transport

Assimilation

Absorbed food is used to provide energy and form new materials and cells

Egestion

Removal of undigested waste material

Mouth

Where food is taken in. Physical and chemical digestion takes place here. Food forms into a ball known as a bolus

Oesophagus

Food moves along the oesophagus by peristalsis. This involves the walls of the oesophagus contracting

Stomach

Muscular walls of the stomach churns the food. Hydrochloric acid maintains a low pH for optimum activity of enzymes and kills bacteria

Small intestine

Villi secrete digestive enzymes and provide large surface area to absorb digested food

Large intestine

Large quantities of water are absorbed back into the body

Rectum

Faeces is stored here

Anus

Faeces passes out of the body here