5.3.4. Overview of the Stomach - Pepsinogen and Gastric Mucus

Question 1

Where is Pepsinogen Released from?

Answer 1

The Chief Cells of the Gastric Glands

Question 2

Do the Chief Cells lie Superficial or Deep to the Mucous Cell Neck?

Answer 2

Deep

Question 3

Do the Chief Cells lie Superficial or Deep to the Parietal Cells?

Answer 3

Deep

Question 4

What is Pepsinogen?

Answer 4

An inactive Precursor of Pepsin

Question 5

What is another term used to describe an inactive pre-cursor?

Answer 5

A Zymogen

Question 6

What is Pepsin responsible for?

Answer 6

The Breaking down or Proteins into smaller Peptides

Question 7

What is the Advantage of storing Pepsinogen, as a Zymogen?

Answer 7

It prevents Cellular Digestion

Question 8

What are the mechanisms for control of Pepsin Secretion?

Answer 8

These run parallel to Gastric Acid Secretion:

1. The increase in Vagal Nerve Activity, increasing the Acetylcholine acting on the Chief Cells
2. The increase in Gastrin acting on the Chief Cells
3. The increase in Histamine acting on the Chief Cells

Question 9

What activates Pepsinogen to become Pepsin?

Answer 9

The Hydrogen Ion from the Gastric Acid secreted

Needs to be a pH less than 3

Question 10

What is Gastric Mucous produced by?

Answer 10

1. The Surface Epithelial Cells

2. The Mucous Neck Cells

Question 11

What is the function of the Gastric Mucous?

Answer 11

It has a Cytoprotective Role

Question 12

What is the Cytoprotective Role of the Gastric Mucous?

Answer 12

1. It Protects the Mucosal Surface from Mechanical Injury

2. It releases Bicarbonate which Neutralizes the Gastric Acid and Pepsin - this prevents self-digestion