dhd

The digestive system

Digestion breaks down large molecules into smaller molecules

1. Many of the molecules in our food are polymers

2. Large, complex molecules composed of long chains of monomers (small basic molecular units)

3. Proteins are some carbohydrates are polymers. Carbohydrates – the monomers are called monosaccharides. Contain elements carbon, hydrogen and oxygen. Proteins – monomers are called amino acids – contain carbon, hydrogen, oxygen and nitrogen.

4. Polymers in food insoluble – directly absorbed into our bloodstream and assimilated into new products.

5. Polymers have to be hydrolysed (broken down) into smaller, more soluble molecules by adding water.

6. Process happens during digestion

7. Hydrolysis is catalysed by digestive enzymes.

Each part of the digestive system has a specific function

- All organs have a role in breaking down food and absorbing nutrients:

1. Oesophagus – Tube takes food from mouth to stomach using eaves of muscle contractions called peristalsis. Mucus is secreted from tissues in the walls to lubricate foods passage downwards.

2. The stomach – small sac. Has lots of folds allowing stomach to expand.…