Monday, April 5, 2010

How are large molecules changed into smaller molecules?

Answer:

Our body produces digestive enzymes to digest food. These enzymes cut up the large molecules into smaller molecules and speeds up the process of digestion without being used up. Each enzyme digest one type of food only.

DIGESTIVE SYSTEM!

Mouth:

- Two actions take place - physical & chemical

Physical Action

1. Teeth grind the food into smaller pieces.

2. Tongue roll food into bolus.

Chemical Action

1. Starch is broken down by enzyme salivart amylase by maltose.

Chemical equation for above action:

Starch -------------------> maltose

(salivary amylase)

Stomach:

- Elastic, muscular bag with thick and well developed stomach wall.

- Churns food into liquid chyle

- Stomach wall produces enzyme pepsin as well as hydrochloric acid.

- Pepsin will break down protein into amino acids
- Hydrochloric acid has two functions:

1. Provide a suitable medium (pH.2) for pepsin to work well.

2. Kill foreign particles.

Duodenum (small intestine):
-After food have been partially digested in the stomach, it will move on to the duodenum.
-All classes of food will be digested.
- Enzmes present are produced from the pancreas and send to the small intestine via the pancreatic duct.
-Enzymes present are:
1. Pancreatic amylase
2. Maltase
3. Lipase
4. Trypsin