Digestion

Digestion is presented as a means of transforming complex food substances into smaller molecules prior to absorption into the body. The functions of the human digestive systems are examined, as well as the role of enzymes as catalysts.

Digestion is the breaking down of large molecules of food into smaller ones, eventually going into the blood.

1. Mechanical Digestion
2. Chemical Digestion

Enzymes

• Salivary glands make amylase
• Glands in stomach (Gastric Glands) make Pepsin (Protease)
• Pancreas make amylase, lipade, trypsin (Protease)

Enzyme Functions

• Amylase breaks down starch into maltose
• Protease (pepsin, trypsin) breaks down protein into polypeptides
• Lipase breaks down fat into glycerol and free fatty acids

Test for starch: Iodine turns from brown to black

Test for glucose: heat substance in water bath with benedicts solution, will turn orange if glucose is present

How absorption is increased in small intestine

• Vili: folds, increase surface area
• Each villus: has many blood capillaries

Factors which affect enzyme activity

• pH, there is an optimum pH, above or below this results in denaturation
• Temperature, there is an optimum temperature.
  • In body 37 C is optimum
  • Low temperature slows down enzymes
  • High temperature permanantly denatures enzymes

What is an enzyme

• A protein which acts as a catalyst, which speeds up the rate of reaction.

When enzymes are used

• Washing up powder. Protease breaks down protein stains.

Teeth

• Incisor x 4 - cutting and biting
• Canine x 2 - piercing, tearing, grasping
• Premolar x 4 - grinding and chewing
• Molar x 6 - grinding and chewing

Note: You must know the structure of the tooth

Function of large intestine

• absorb - water, vitamins, and minerals
• colon produces vitamin K

About the Author