2.27 understand the processes of ingestion, digestion, absorption, assimilation and egestion

Digestion: Process where large insoluble molecules are broken down into small soluble ones

Absorption: When soluble molecules taken from the small intestine are transported through the circulatory system (blood) to cells of the body

Assimilation: The absorption of nutrients into the body after digestion and the conversion of nutrients to living tissue (to make new cells)

Ingestion: To take into the body through the mouth

Egestion: to excrete waste products from the body (e.g. undigested products such as faeces)

Peristalsis: wave like contractions that move food through the digestive tract. It begins in the oesophagus when food is swallowed

2.26 describe the structures of the human alimentary canal and describe the functions of the mouth, oesophagus, stomach, small intestine, large intestine and pancreas

Alimentary canal: The passage along which food passes through the body from mouth to anus during digestion

The mouth: Mechanical digestion (chewing) mixes with saliva so enzymes can begin to break down food (amylase)

The oesophagus: Tube connecting mouth and stomach. Next to the trachea: peristalsis- a wave of muscular contractions that moves food downwards

The stomach: Produces and secretes substances need for digestion (stomach acid). Churning mechanically digests while enzymes do so chemically. Stomach acid kills bacteria and lowers the pH so enzymes can work

Small intestine: Absorbs minerals and nutrients (digested molecules) into the bloodstream. Villi cover the insides giving it a larger surface area in which molecules can diffuse through into the blood

Large intestine: Absorbs water from undigested food: producing faeces

Pancreas: Produces enzymes (lipase, amylase and protease) needed for digestion

2.25 understand that energy requirements vary with activity levels, age and pregnancy

Young people require a lot of energy because activity levels tend to be higher and energy is being used for growth. As a person ages their energy requirements drop. Having a less or more active lifestyle also has an effect on energy requirements. When a woman is pregnant she requires more energy because she needs energy for supporting her herself and her baby.