Enzymes in the stomach and the mouth

Question 1

How does chewing help the chemical attack on starch?

Answer 1

• Chewing breaks down the food and increase the surface area (mixes food with saliva)
• Teeth, jaws and tongue- reduce size of food and increase SA for catabolic enzymes to work on the food
• The salivary amylase continues to break down starch.

Question 2

What enzyme is in the saliva?

Answer 2

• Glands in the mouth secrete saliva containing salivary amylase which breaks down starch into glucose
• Most active at pH 7
• Active large starch molecules into smaller dissaccharide units

Question 3

What does hydrochloric acid in the stomach do?

Answer 3

• Breaks down and kill the bacteria in foods
• Turns food into chyme
• Fights disease

Question 4

What do stomach proteases do?

Answer 4

• Break down protein into amino acids
• Break down peptide bonds in the protein foods to free the amino acids
• Break down large protein molecules into smaller protein molecules
• Most active at pH2 and 37 degrees Celsius

Question 5

In the stomach was do epithelial cells do?

Answer 5

• Secrete mucus which acts as a lubricant
• Produce hydrochloric acid
• Secrete digestive enzymes

Question 6

In the stomach was do the mucus layers do?

Answer 6

• The muscularis churn and mix food

Grind food together with digestive juices

Question 7

In the stomach was does the connective tissue do?

Answer 7

• Support tissues

- Offer strength and support

Question 8

In the stomach was do the blood vessel do do?

Answer 8

• Bring arterial to the stomach and also return tofrom the stomach to the liver

Question 9

What is mechanical digestion?

Answer 9

• The physical act of breaking down the food by non-chemical means
  (breaking down food physically)

Question 10

What is chemical digestion?

Answer 10

• Breaking down the food into simpler nutrients that can be used by the cells.
• Enzymes breaking down food

Question 11

What is the purpose of mucus in the stomach?

Answer 11

Stomach mucus protects the gastrointestinal cells from the damage that gastric juices can cause

Question 12

Pepsin

Answer 12

• The pH causes the enzymes to be dormant and active
• pH works best at pH 3-4
• Stomach acid does not digest protein- activates pepsinogen which then becomes pepsin that is secreted by the stomach wall

Question 13

Characteristics of the digestive system which prevent self- digestion

Answer 13

• Mucus- protects the stomach from peptic ulcers (when the acids comes in contact with stomach walls)
• Pancreas make bicarbonate solution to neutralise chyme to pH 7
• Enzymes are inactive in the stomach until they are mixed with stomach acids

Question 14

What is a type of salivary amylase?

Answer 14

• Enzyme ptyalin is contained in the saliva

- Ptyalin changes starches to soluble sugars