B3.7 Making Digestion Efficient

Question 1

Roughly how many glands are in the lining of the stomach, and what do they secrete?

Answer 1

35 million glands, which secrete pepsin, a protease enzyme.

Question 2

What does the stomach produce so pepsin works most effectively?

Answer 2

A concentrated solution of hydrochloric acid

Question 3

What does the stomach produce to protect itself?

Answer 3

A thick layer of mucus, which coats the stomach and stops it from being digested by the acid / enzymes.

Question 4

The small intestine’s enzymes work best in alkaline environments, so what happens when the food moves from the stomach to the small intestine?

Answer 4

The liver makes bile, a green-yellow alkaline liquid which is stored in the gall bladder until it is needed. As food enters the small intestine, bile is squirted onto it, neutralising the acid.

Question 5

What does bile do to aid the digestion of lipids?

Answer 5

Since lipids do not mix with all the watery liquids in the digestive system, bile emulsifies it - it breaks the large drops of fat into smaller droplets. This provides a much larger surface area for lipase enzymes to act and helps to quickly break down lipids to fatty acids and glycerol.