Upper GI Structure/Function

Question 1

What is semi-fluid of partially digested food in the stomach called?

Answer 1

chyme

Question 2

Where is voluntary muscle located in the GI tract?

Answer 2

upper 1/3 of esophagus

Question 3

What are the 4 general layers of the GI tract? (luminal inward)

Answer 3

Mucosa
Submucosa
Muscularis Externa
Adventitia/Serosa

Question 4

What are the thee layers of the mucosa?

Answer 4

Epithelium
Lamina Propria
Muscularis mucosae

Question 5

What is the role of the mucosal epithelium? (general)

Answer 5

mucosal function

Question 6

What is the role of the lamina propria? (general)

Answer 6

supports epithelium, contains lymphocytes and plasma cells

Question 7

What is the role of the muscularis mucosae? (general)

Answer 7

local movements and folding of mucosa

houses capillaries

Question 8

Waht is submucosa? What is it’s function?

Answer 8

layer of loose collagenous and adipose tissue
supports the mucosa
contains large blood vessels and lymphatic vessels

Question 9

Where does the submucosa contain mucous secreting glads?

Answer 9

esophagus and duodenum

Question 10

What part of the enteric nervous system is in the submucoa? What type of innervation is this?

Answer 10

submucosal (meissner’s) plexus

parasympathetic ganglia

Question 11

Which layer of the muscularis externia is internal? external?

Answer 11

internal: circular
outer: longitudinal

Question 12

What is the role of the muscularis externa?

Answer 12

peristalsis

Question 13

What type of muscle is muscularis externa?

Answer 13

smooth

Question 14

What part of the enteric nervous system is in the muscularis externa? what does it control?

Answer 14

myenteric (auerbach’s) plexus

control’s peristalsis

Question 15

What is the adventitia/serosa?

Answer 15

outermost covering of the GI tract

Question 16

Define adventitia

Answer 16

loose connective tissue layer surrounding he GI tract wtihin he peritoneal cavity

Question 17

Define serosa

Answer 17

simple squamous epithelium (mesothelium) along with conntective tissue that covers the GI tract within the peritoneal cavity
(epithelium secretes serous fluid to lubricate)

Question 18

What neurotransmitters does the enteric nervous system use?

Answer 18

Ach
NE
serotonin

Question 19

What does the submucosal/meissner’s plexus do?

Answer 19

controls mucosal movement, secretory activity and blood flow

Question 20

What does the myenteric/auerbach’s plexus do?

Answer 20

controls peristaltic gut movements

Question 21

What type of mucosa is in the upper gi tract and anus? function?

Answer 21

stratified squamous, non-keratinized, contains langerhans cells
protective

Question 22

What type of mucoas is found in the stomach? function?

Answer 22

simple columnar epithelium
thick mucous, traps bicarbonate ions
gastric pits
secretory
contains abundance of tubular glands

Question 23

What type of mucosa is found in the SI? function

Answer 23

absorptive

mucosa is folded into villi to maximize surface area

Question 24

What type of mucosa is found in the LI? function?

Answer 24

absorptive/protective

produces mucin and absorbs water

Question 25

What secretes mucous to help propel food down the esophagus?

Answer 25

esophageal cardiac glands

Question 26

Where are esophageal glands located? function?

Answer 26

submucosa arranged in acini contain mucous cells and serous cells secrete pepsinogen & lysozyme

Question 27

Where is the adventitia/serosa border of teh esphoagus?

Answer 27

the diaphragm

Question 28

What cell types make up the GEJ

Answer 28

stratified squamous to simple columnar

Question 29

What are the 2 physiological sphincters of the esophagus

Answer 29

pharyngoespophageal-prevents reflux from esophaus to pharynx | gastroesophageal-prevents reflux from stomach to esophagus

Question 30

What are the 4 anatomical regions of the stomach?

Answer 30

cardia fundus body pyloris

Question 31

What makes up gastric juice?

Answer 31

HCl, pepsin, rennin, gastric lipase

Question 32

Describe the lamina propria of the stomach

Answer 32

contains gastric glands | enterochromaffin type cells

Question 33

What do enterochromaffin-type cells do?

Answer 33

secrete histamine in response to vagus nerve to increase acid secretion

Question 34

How many layers of muscle are in the stomach?

Answer 34

3 | circular, oblique, longitudinal

Question 35

What are gastric pits?

Answer 35

pitted surface of mucosa

Question 36

What are gastric glands?

Answer 36

tupular columns of epithelial cells | 3 regions: isthmus, neck, base

Question 37

What are the 6 cell typesof simple columnar epithelium in gastric glands?

Answer 37

1. surface mucous/lining cells (gastric pit) 2. parietal cells (isthmus, neck & base) 3. neck mucous cells (neck & base) 4. Chief (peptic) cells (base) 5. Enteroendocrine cells (base) 6. Stem/regenerative cells (neck)

Question 38

What type of mucous is secreted by surface lining cells? mucous neck cells?

Answer 38

surface lining cells-thick & dense, adheres to mucosa and protects against acid mucous neck cells-soluble, lubes stomach to aid digestion

Question 39

What substances do enteroendocrine cells secrete?

Answer 39

``` usually a single bioactive agent G-cells: gastrin EC cells: serotonin D cells: somatostatin A cells: enteroglucagon ECL cells: histamine can act paracrine or endocrine ```

Question 40

What do parietal cells secrete? features of parietal cells?

Answer 40

``` HCl Intrinsic factor secretory cnaliculous-makes pyramidal, microvilli extend into Tubulovesicular network lots of mitochondria ```

Question 41

What do chief cells secrete? features of chief cells?

Answer 41

pepsinogen, rennin, gastric lipase (from zymogen secretory granules) lots of RER & golgi base of gastric glands binding to secretin leads to rapid exocytosis of secretory granules vagus nerve stimulates enzyme release

Question 42

Describe the regenerative stem cells of the gastric glands

Answer 42

found in neck of gastric gland mitotic figures daughter cells differentiate and migrate

Question 43

What is mucosal restitution?

Answer 43

surface epithelium repair after injury by rapid migration of epithelial cells lying deep in the protected enrionment of the pits

Question 44

What type of glands are found in the fundus/body?

Answer 44

straight tubular

Question 45

What types of glands are found in the pylorus?

Answer 45

branched, mucous neck cells predominate

Question 46

What type of glands are found in the cardiac region?

Answer 46

shallower gastric pits, highly coiled

Question 47

What is the cephalic phase?

Answer 47

brain anticipates meal parasympathetic signals vagus-->gastrin secretion 30% gastric acid released

Question 48

What is the gastric phase?

Answer 48

food enters stomach->distention->increased G cell activity | 60% total gastric acid released

Question 49

What is the intestinal phase?

Answer 49

Chyme released into duodenum enterogastric relfex 10% gastric acid released

Question 50

What is the enterogastric reflex?

Answer 50

distention of the intestine-->gastric-inhibitory impulses by ENS