Chapter 24.7-24.12

Question 1

what is the physiological purpose of the oesophagus?

Answer 1

-convey the bolus to the stomach
-secretes mucus to promote bolus movement
-peristaltic contractions aid propulsion of bolus

Question 2

following peristaltic contractions, what is the name of the structure that opens to allow bolus entry to stomach and what is the name of the structure that allows its exit?

Answer 2

-lower oesophageal (cardiac) sphincter
-pyloric sphincter

Question 3

what is the first symptom of gastroesophageal reflux disease? (GERD)

Answer 3

heartburn

Question 4

name the 3 phases of the swallowing reflex

Answer 4

-voluntary
-pharangeal
-oesophageal

Question 5

name the 4 regions of the stomach

Answer 5

-cardia
-fundus
-body
-pylorus

Question 6

which is the largest part of the stomach

Answer 6

the body

Question 7

the wider part of the pylorus is called:

Answer 7

the pyloric antrum

Question 8

the narrower part of the pylorus is called:

Answer 8

the pyloric canal

Question 9

what are the main functions of the stomach?

Answer 9

-storage and mixing of chyme
-digestion
-regulation of gastric enzyme secretion
-production of intrinsic factor to absorb vitamin B12

Question 10

why does the stomach have a relatively small volume?

Answer 10

inner surface foldings (rugae)

Question 11

what is the approximate volume a full stomach can hold?

Answer 11

4L

Question 12

what is the name of the additional layer of muscle in the stomach called?

Answer 12

the oblique muscle layer

Question 13

describe the muscle thickness of the different regions of the stomach and how it relates to their physiological function

Answer 13

-fundus and body: only layers that expand (thin muscle)
-pyloric region: churns and empties food so strong contractions are required (thick muscle)

Question 14

describe the stomach’s response to filling

Answer 14

-fundus and body relax to increase stomach volume
-rugae flatten
-vigorous contractions in antrum and pylorus
-propulsion via peristaltic contractions and retropropulsion
-pylorus delivers small amounts of chyme to duodenum

Question 15

what is the typical gastric pressure in the stomach?

Answer 15

5mmHg

Question 16

why is gastric pressure relatively constant?

Answer 16

-receptive relaxation
-adaptive relaxation
-plasticity of smooth muscle

Question 17

what histological feature allows for stomach smooth muscle contraction and acts as an electrical pacemaker?

Answer 17

-interstitial cells of Cajal (ICCs)
-found in myenteric plexus
-3 slow waves per minute in stomach

Question 18

list the cell types present in the gastric pits of the stomach

Answer 18

-surface mucus cell
-mucous neck cell
-parietal cell
-chief cell
-G cell

Question 19

what is the role of parietal cells in gastric pits?

Answer 19

secrete hydrochloric acid and intrinsic factor

Question 20

what is the role of chief cells in gastric pits?

Answer 20

secrete pepsinogen and gastric lipase

Question 21

what is the roll of G cells in gastric pits?

Answer 21

secretes gastrin

Question 22

name a common defect of the stomach and it’s effect

Answer 22

-hypertrophic pyloric stenosis
-common defect in infants
-pyloric sphincter greatly thickened
-inhibiting normal emptying of the stomach

Question 23

name the tunica of the stomach from outermost to innermost

Answer 23

-serosa/visceral peritoneum (2 layers) outer: simple squamous epithelium and inner: connective tissue
-muscularis (3 layers) outer: longitudinal, middle: circular layer and inner: oblique layer

Question 24

what type of epithelium makes up the mucous lining of the stomach?

Answer 24

simple columnar epithelium

Question 25

describe the roll of gastric surface mucous cells

Answer 25

-produce alkaline surface mucous acting as barrier
-protect stomach wall from damage by digestive enzymes
-cells connected by tight junctions: additional barrier
-surface mucous cells rapidly replicated when damaged