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Chapter 17 Topics 9-11 Digestive
List the 3 types of secretory cells found in gastric glands, and what they secrete.
1) Mucous Cells (mucous) 2) Chief Cells (digestive enzymes) 3) Parietal Cells (hydrochloric acid and intrinsic factor)
Secreted by mucous cells, this provides a vicious, alkaline protective layer on the stomach's inner surface.
Secreted by chief cells, this digestive enzyme is inactive until it contacts the hydrochloric acid from parietal cells to form pepsin.
Formed from pepsinogen in the presence of hydrochloric acid, this is a protein-splitting enzyme that digests nearly all types of protein into polypeptides.
Secreted by parietal cells, this provides the acid environment needed for production and action of pepsin.
Secreted by parietal cells, this aids in vitamin B12 absorption in the small intestine.
The products of the mucous cells, chief cells, and parietal cells together form what?
What are the 2 digestive reflexes.
1) Enterogastric Reflex 2) Vomiting Reflex
A digestive reflex triggered by distension of the small intestine wall and inhibits peristalsis in the stomach to slow down movement of food into the duodenum.
A digestive reflex that empties the stomach in the reverse of the normal direction.
Following a meal, the blood concentration of bicarbonate ions increases, and the urine excretes excess bicarbonate ions.
What are the triggers of the cephalic phase?
Sight, smell, and thought of food
A hormone produced in the stomach that functions to inhibit acid secretion.
A peptide hormone that stimulates the 3 secretory cells, stimulating the digestive process.
In what structure are the chief cells, parietal cells, and mucous cells located?
What hormone inhibits the digestive process, and how does it inhibit it?
Somatostatin, because it inhibits gastrin, thus, slowing down acid secretion and digestion
What hormone stimulates the digestive process, and how does it stimulate it?
Gastrin, because it stimulates the 3 secretory cells, thus, increasing acid secretion and digestion
What effect does the PNS and SNS have on the production and release of somatostatin?
PNS inhibits somatostatin, thus increasing digestion; ANS stimulates somatostatin, thus inhibiting digestion because the increased somatostatin inhibits the secretory cells
List the 3 triggers of the gastric stage.
1) Stretch of stomach lining 2) Presence of protein 3) Increased Ph
In the gastric stage, what 3 chemicals are released by stomach cells in response to the triggers?
1) Histamine 2) ATCH 3) Gastrin
In the gastric stage, PNS impulses and gastrin promote the release of this hormone from gastric mucosal cells, which stimulates additional gastric secretion.
In the gastric stage, PNS impulses cause this to be released from vagus nerve endings suppresses somatostatin and stimulates more gastric secretion.
A peptide hormone released in the stomach by PNS impulses in the gastric stage that increases secretory activity of gastric cells.
What type of food moves quickest through the stomach?
What type of food moves slowest through the stomach?
Solids, especially fatty foods
What cells are stimulated by histamine, ATCH, and gastrin?
The parietal cells, mucous cells, and chief cells
List the 3 triggers of the intestinal stage.
1) Stretch of the duodenum 2) Lipids & Proteins 3) Acidic pH
In the intestinal stage, which hormone is released due to the triggers of lipids and proteins?
In the intestinal stage, what is the result of the release of CCK?
It decreases gastric motility, and intestinal somatostatin is released, which inhibits release of gastric juice
In the intestinal stage, which hormone is released due to the trigger of acidic pH?
In the intestinal stage, what is the result of the release of secretin?
It causes the pancreas to secrete bicarbonate ions
A band of smooth muscle that opens to let pancreatic juice and bicarbonate ions enter the duodenum.
Sphincter of Oddi