Unit 6: Human Health And Physiology

Lesson 6.1 Digestion

6.1.1 Explain why digestion of large food molecules is essential.

• Large food molecules are polymers, which must be broken down into monomers (via hydrolysis) in order to be absorbed into the blood.

6.1.2 Explain the need for enzymes

in digestion.• Enzymes speed up

the rate at which polymers are broken down into monomers.

6.1.3 State the source, substrate, product and optimum pH conditons for one amylase,

one protease and one lipase.

Amylase Protease Lipase

Example of this enzyme

Salivary amylase

Pepsin Pancreatic lipase

Source Salivary glands Wall of stomach

Pancreas

Substrate Starch Proteins Triglycerides (fats and oils)

Product Maltose Small polypeptides

Fatty acids and glycerol

Optimum pH 7-8 1.5-3 7-8

6.1.4 Draw a diagram of the digestive system.

• Locate: mouth, esophagus, stomach, small intestine, large intestine, anus, liver, pancreas, gall bladder.

6.1.5 Outline the function of the stomach, small intestine and large

intestine.• Stomach- primary site

for protein digestion.• Small intestine- primary

site for overall nutrient absorption.

• Large intestine- water used in the digestive process is reabsorbed back into the body.

6.1.6 Distinguish between absorption and assimilation.

• Absorption- the transfer of nutrients from the digestive tract into the blood stream, usually through villi in the small intestine.

• Assimilation- uptake of nutrients from blood stream into body tissue. Occurs after absorption.

Pictured: microvilli on a villus.

6.1.7 Explain how the structure of the villus is related to its role in absorption of

the end products of digestion.

• Villi have a large surface area, gated ion channels, and are dense in mitochondria, which provide energy for the active transport of nutrients.