Stomach (Gastric Cells and Secretions)

What cells are present in the gastric pits, synthesize soluble mucins, and secrete mucin for lubrication and protection?

Mucous neck cells are present in the gastric pits, specifically in the neck region; synthesize soluble mucins (e.g., MUC5AC) that are less viscous than the insoluble mucins produced by surface cells, and secrete mucin to provide lubrication and protection.

What facilitates the movement of secretions and is less viscous?

Soluble mucin facilitates the movement of secretions from parietal and chief cells into the gastric lumen; it is less viscous, allowing for easier mixing and transport of stomach contents.

What cells produce HCl and intrinsic factor?

Parietal cells. Production is stimulated by histamine, acetylcholine, and gastrin; intrinsic factor is essential for the absorption of vitamin B_{12} in the ileum.

What cells produce enzymes, primarily pepsinogen and gastric lipase?

Chief cells

What cells secrete gastrin, stimulating parietal cells to produce HCl?

G cells secrete gastrin into the bloodstream, which stimulates parietal cells to produce HCl and promotes gastric motility.

What cells secrete somatostatin, inhibiting the release of gastrin and HCl?

D cells secrete somatostatin, which inhibits the release of gastrin, HCl, and other gastrointestinal hormones, thereby regulating gastric acid secretion.

What extends deeply into the parietal cell, increasing the surface area for acid secretion?

Canaliculi extend deeply into the parietal cell, increasing the surface area for acid secretion; typically two are extensively branched, maximizing secretory capacity.

What blocks the hydrogen-potassium ATPase pump, inhibiting HCl secretion?

Omeprazole blocks the hydrogen-potassium ATPase pump, thereby inhibiting HCl secretion; used to treat conditions like acid reflux and peptic ulcers by reducing gastric acid production.

What is produced during HCl synthesis and transported back into the capillary?

Bicarbonate (HCO_3^-) is produced during HCl synthesis within parietal cells and transported back into the capillary via chloride-bicarbonate exchanger.

What refers to increased HCl secretion leading to elevated bicarbonate levels?

Alkaline tide refers to increased secretion of HCl leading to elevated bicarbonate levels in the blood, temporarily increasing the blood's pH, creating a postprandial alkaline tide.

What phase is initiated by olfaction, taste, and visual stimuli related to food?

The cephalic phase is initiated by olfaction, taste, and visual stimuli related to food; signals are transmitted via the parasympathetic nervous system (vagus nerve) to the brain.

What directly stimulates parietal cells, increasing HCl secretion?

Vagus nerve stimulation directly stimulates parietal cells, increasing HCl secretion through activation of muscarinic receptors; stimulates enterochromaffin-like (ECL) cells to release histamine; stimulates G cells to release gastrin into the bloodstream.

What increases protein digestion by stimulating parietal cells to produce HCl?

Gastrin increases protein digestion by stimulating parietal cells to produce HCl, which activates pepsinogen to pepsin.

What aids in the mixing of food in the pylorus region?

Mucus aids in the mixing of food in the pylorus region, ensuring thorough digestion prior to entry into the duodenum.

What cells divide and differentiate to maintain the gland's cellular composition?

Stem cells divide approximately every week to regenerate mucous neck cells and surface mucous cells; differentiate into parietal cells, chief cells, and enteroendocrine cells, maintaining the gland's cellular composition.

What ulcers are linked to brain injuries and increased vagus nerve stimulation?

Curling's ulcers are linked to brain injury and increased vagus nerve stimulation