Flashcards in Gastric Secretions Deck (25):
What are the functions of gastric secretions?
- Digestion of proteins
- Protection of the stomach lining
- Absorption of VB12
- Protection again food-borne infections
- Helps convert enzymes to active form
Role of chief cells
Secrete pepsinogen, precursor of the active pepsin which breaks down proteins
Role of parietal cells
Secrete HCl (gastrin acid), decreasing stomach pH and is where intrinsic factor is released
Role of ECL cells
Entero-chromaffin like cells which are always close to parietal cells. Secrete histamine which is a trigger for gastric acid release
Role of G cells
Release gastrin hormone, which then stimulates the ECL cells and cause acid secretion, cascade effect
Role of D cells
Secretes somatostatin which has a negative feedback role
Role of mucin neck cells
Secrete mucus to protect stomach lining
Role of stem cells
Differentiate into any of the cells within the gastric pit
What areas of the stomach are G cell rich?
Antrum and pylorus
What is the alkaline tide?
More acid is secreted after eating so more OH- ions are removed into the blood as HCO3- . Acid one way, base the other.
What does omeprazole do?
Antacid, blocks the H+/K+ transporter, preventing acid secretion. Sits in the stomach lumen and is activated by a low pH.
What does aspirin do to the stomach lining?
PG inhibitor so disrupts the mucus and bicarbonate layer protecting the stomach.
What is intrinsic factor secreted from?
Why is intrinsic factor needed?
VB12 absorption, a lack causes pernicious anaemia, which is treated with a cyanocolbalmin injection
What are the 3 ways that causes acid to be secreted into the stomach?
- Ach acting directly on the parietal cells causing H+ secretion.
- ACh acting on the G cells that produce gastrin, which acts directly on the cell causing H+ secretion.
- Gastrin production acting on the ECL cells, increasing histamine and acid secretion
What does cimetidine do?
Block histamine receptors
When is somatostatin released?
After the ingestion of food when stomach pH is low , D cells secrete somatostatin, which is a peptide hormone and has a negative feedback effect on gastrin.
Examples of the cephalic reflex regulating acid secretion
- Food in mouth leads to the secretion of HCL
- Anger and tension increases acid secretion
- Fear and depression decreases acid secretion
Which is the most dominant regulator of acid secretion in the stomach?
How does the gastric regulation of acid secretion work?
Stimulated by distension of the stomach (vast-vagal), hyperoncity, alcohol and AAs.
Inhibited by H+
How does the intestinal regulation of acid secretion work?
Where is the oxyntic gland area?
Body and fungus
Where is gastrin produced?
Antrum in the G cells
How many parietal cells are in the human stomach and what is the concentration of the acid they produce?