Gastric Juice Formation & HCl

What do Chief cells secrete?

Chief cells secrete pepsinogen and gastric lipase.

What does pepsinogen do in the stomach?

Pepsinogen (inactive precursor enzyme -zymogen) is converted to pepsin (active form - protease), which breaks down proteins.

Autocatalytic effect

When pepsinogen is converted to pepsin, that activates more pepsinogen leading to the creation of more pepsin.

What does gastric lipase do in the stomach?

Gastric lipase begins the digestion of lipids (fats).

• breaks down triglycerides into diglycerides and free fatty acids.

How is gastric juice formed?

Gastric juice formation is stimulated by:

- Gastrin (from G cells)

- ACh (from parasympathetic nerve fibers)

- Histamine (from mast cells)

What is the process of HCl formation?

• Gastrin, ACh, and Histamine trigger parietal cells to secrete HCl.

How Does Histamine Help in HCl Production?

Histamine, released by mast cells, binds to H2 receptors on parietal cells and stimulates the production of HCl.

What Role Do CO2 and H2O Play in Making HCI?

Inside stomach cells, CO2 and H20 combine to form carbonic acid (H2CO3), which then breaks down into hydrogen ions (H+) and bicarbonate ions (HCO3-). The H+ ions are used to make HCI.

What is the Alkaline Tide and How Does It Happen?

The alkaline tide occurs when the stomach produces acid, releasing bicarbonate ions (HCO3-) into the bloodstream. This temporarily makes the blood more alkaline (less acidic).

What is the Chloride Shift and How Does It Relate to HCl Formation?

The chloride shift is the process by which chloride ions (Cl-) from the blood are exchanged for bicarbonate ions (HСО3-) in the stomach. Chloride is needed to form HCl.

What Does the H+/K+ Pump Do in the Stomach?

The H+/K+ pump actively pumps hydrogen ions (H+) into the stomach to make it acidic and produce HCl. It also exchanges potassium ions (K+) to maintain the cell's balance.