Gastric secretion is stimulated chiefly by three chemicals:
acetylcholine (ACh), histamine, and gastrin
. Below pH of 2, stomach acid inhibits the parietal cells and G cells; this is a negative feedback loop that winds down the gastric phase as the need for pepsin and HCl declines.
Where are gastric juices released during digestion?
The food you chew and swallow is called a bolus. It mixes with the gastric juices secreted by special glands found
in the lining of your stomach
, which include: Cardiac glands at the top part of the stomach. Oxyntic glands in the main body of the stomach.
What causes the release of gastric juice?
Gastrin
is a hormone that is produced by ‘G’ cells in the lining of the stomach and upper small intestine. During a meal, gastrin stimulates the stomach to release gastric acid. This allows the stomach to break down proteins swallowed as food and absorb certain vitamins.
During which phase of gastric secretion is gastric juice released?
The gastric juice secreted during
the cephalic phase
is rich in pepsinogen, but also contains some acid. The secretion of both pepsinogen and acid is due to impulses in the vagus nerve. Stimulation of the nerves releases acid both directly from the oxyntic cell and indirectly via the release of gastrin (Fig. 4.11).
What stimulates gastric juice secretion and gastric emptying?
When partially digested food fills the duodenum, intestinal mucosal cells release a hormone called
intestinal (enteric) gastrin
, which further excites gastric juice secretion.
What are the 3 main hormones that regulate digestion?
The five major hormones are: gastrin ( stomach ), secretin ( small intestine ),
cholecytokinin
(small intestine), gastric inhibitory peptide (small intestine), and motilin (small intestine).
What are the three secretions of the stomach?
The secretions of the exocrine gastric glands – composed of the mucous, parietal, and chief cells – make up the
gastric juice
. The products of the endocrine cells are secreted directly into the bloodstream and are not a part of the gastric juice.
What is the most important digestive enzyme in the stomach?
Pepsin
is a stomach enzyme that serves to digest proteins found in ingested food. Gastric chief cells secrete pepsin as an inactive zymogen called pepsinogen.
Can your stomach digest itself without mucus?
THE STOMACH does not digest itself because it is lined with epithial cells, which produce mucus
. This forms a barrier between the lining of the stomach and the contents. Enzymes, which make up part of the digestive juices are also secreted by the stomach wall, from glands with no mucus barrier.
What are the symptoms of too much acid in your stomach?
- abdominal discomfort, which may be worse on an empty stomach.
- nausea or vomiting.
- bloating.
- heartburn.
- diarrhea.
- decreased appetite.
- unexplained weight loss.
What increases gastric secretion?
Gastric secretion is stimulated by
the act of eating (cephalic phase) and the arrival of food in the stomach (gastric phase)
. Arrival of the food in the intestine also controls gastric secretion (intestinal phase). The secreted fluid contains hydrochloric acid, pepsinogen, intrinsic factor, bicarbonate, and mucus.
What is gastric juice function?
Gastric juice is a unique combination of hydrochloric acid (HCl), lipase, and pepsin. Its main function is
to inactivate swallowed microorganisms
, thereby inhibiting infectious agents from reaching the intestine.
What are the 3 components of gastric juice and what is their function?
Answer: Gastric juice contains three substances:
hydrochloric acid, enzyme pepsin and mucus
. Their functions are: Hydrochloric acid in the stomach is used to make the medium acidic to facilitate the action of the enzyme pepsin and to kill germs if any.
What stimulates the secretion of HCl in the stomach?
A meal in the stomach stimulates G-type enteroendocrine cells in the gastric mucosa to secrete
gastrin
, which in turn stimulates the secretion of HCl.
Which phase controls how fast the stomach empties?
The intestinal phase
controls the rate of gastric emptying and the release of hormones needed to digest chyme in the small intestine.
What causes the stomach to produce too much acid?
Zollinger-Ellison syndrome is a rare condition in which one or more tumors form in your pancreas or the upper part of your small intestine (duodenum). These tumors, called gastrinomas, secrete large amounts of the
hormone gastrin
, which causes your stomach to produce too much acid.
