2A - Anatomy and Physiology of the Stomach

Question 1

3 layers to the muscular is mucosa of the stomach:

Answer 1

Outermost longitudinal Layer Middle Circular Layer Innermost oblique layer

Question 2

Several factors contribute to the protection of the gastric mucosa, with the most important being a layer of ____.

Answer 2

Alkaline mucus (called gastric mucosal barrier)

Question 3

___ play an important role in protecting the stomach mucosa from injury by enhancing mucus production.

Answer 3

Prostaglandins

Question 4

Mucosal surface of the stomach is a ____ epithelium that is dotted with millions of deep channels called ___ which are lined with columns of specialized cells called ___.

Answer 4

simple columnar gastric pits gastric glands

Question 5

____ cells secrete alkaline mucus.

Answer 5

Mucous neck

Question 6

____ cells secrete HCl & intrinsic factor (IF)

Answer 6

Parietal

Question 7

____ cells secrete pepsinogen and gastric lipase

Answer 7

Chief

Question 8

____ cells - some secrete gastrin (__ cells); others secrete histamine (___ cells)

Answer 8

Endocrine G cells ECL cells

Question 9

What role does HCl play in the stomach?

Answer 9

kills many ingested bacteria aids protein digestion provides necessary pH for pepsin activation stimulates flow of bile and pancreatic juice

Question 10

___ between cells are also part of the mucosal barrier that protects the gastric epithelium from damage.

Answer 10

tight junctions

Question 11

What are the functions of the stomach? (4 things)

Answer 11

Temporarily stores ingested liquids and solids until they are released into small intestine Mechanical digestion - turns food into chyme Chemical digestion - gastric juice Secretes hormones (gastrin and histamine)

Question 12

What are the 3 phases of regulation of gastric secretion and motility?

Answer 12

Cephalic phase Gastric phase Intestinal phase

Question 13

What happens in the cephalic phase of gastric secretion and motility?

Answer 13

• Vagus nerve weakly stimulates gastric juice secretion when food is being chewed in the mouth or even the sight, smell or thought of food. - Vagus nerve stimulates gastrin secretion from the enteroendocrine cells of the gastric glands. - Gastrin further stimulates secretion of gastric juice.

Question 14

What happens in the gastric phase of gastric secretion and motility?

Answer 14

• Begins when food reaches the stomach - Distention of the stomach and protein digestion products (amino acids) stimulate gastrin secretion and hence more gastric juice secretion – this represents a positive feedback loop. - Vagus nerve continues to stimulate gastrin release and gastric motility. - Elevated levels of gastrin stimulate the release of histamine, which in turn increases HCl secretion from parietal cells.

Question 15

What happens in the intestinal phase of gastric secretion and motility?

Answer 15

• Small amounts of acidic chyme enter the duodenum which stimulates the secretion of 3 hormones that inhibit gastric juice secretion. (cholecystokinin, secretin, gastric inhibitory peptide) - GIP also inhibits gastric motility

Question 16

Why is control of chyme leaving the stomach and entering the duodenum critical?

Answer 16

• Keep duodenum from getting too full. - adequate processing of the incoming chyme by the small intestine.

Question 17

____ and ____ activity increase gastric motility – this pushes food towards the duodenum and causes the pyloric sphincter to relax.

Answer 17

Gastrin and vagus nerve

Question 18

____ – products of protein digestion and H+ in the duodenum inhibit vagus nerve activity (occurs during the ___ phase)

Answer 18

Enterogastric reflex intestinal

Question 19

Fatty, acidic chyme stimulates the release of ___, ___ and ___ – all of which inhibit gastric motility and emptying (occurs during the ___ phase)

Answer 19

CCK, secretin, GIP intestinal

Question 20

Answer 20

CARDIA

Question 21

Answer 21

FUNDUS

Question 22

Answer 22

BODY

Question 23

Answer 23

PYLORUS (PYLORIC ANTRUM AND PYLORIC CANAL

Question 24

Which layer is indicated by the red dot?

Answer 24

OUTERMOST LONGITUDINAL LAYER

Question 25

Which layer is indicated by the red dot?

Answer 25

MIDDLE CIRCULAR LAYER

Question 26

Which layer is indicated by the red dot?

Answer 26

INNERMOST OBLIQUE LAYER