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Histo Exam 3 > Digestive System (Upper GI) > Flashcards

Digestive System (Upper GI) Flashcards

1
Q

what are the components of the digestive system?

A

oral cavity & alimentary canal

  • esophagus
  • stomach
  • small & large intestines
  • extrinsic glands
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2
Q

what are the layers of the digestive system?

A

GI system is a layered hollow tube with

  • mucosa
  • submucosa
  • muscularis exerna
  • serosa
  • adventitia
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3
Q

what layer of the GI system is continuous with mesentery?

A

serosa

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4
Q

what layer of the GI system is fixed to the walls of the abdominal cavity?

A

adventitia

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5
Q

in general, what does the GI system do to digest?

A

secretes enzymes and hormones that function in the digestive process

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6
Q

lining of the esophagus is what type of cells?

A

stratified squamous nonkeratinized epithelium

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7
Q

in the esophagus, what secretes mucous?

A

esophageal cardiac glands in the lamina propia

esophageal glands proper in the submucosa

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8
Q

esophageal glands proper primarily secrete mucous but what else do they secrete?

A

lysozyme

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9
Q

in the esophagus, how many layers is the muscularis mucosae and how are the striations arranged?

A

there is a single longitudinal layer of smooth muscle

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10
Q

in the esophagus, the muscularis externa changes from what to what to what at each third?

A

upper third: striated muscle

middle third: smooth & striated

lower third: smooth muscle

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11
Q

function of the esophagus? what primarily is responsible fro this function?

A

conveys food bolus from pharynx to stomach - peristaltic activity of muscularis externa

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12
Q

in the muscularis externa of the esophagus, where would you find the sphincters

A

pharyngoesophageal (upper) & gastroesophageal (lower) in muscularis externa

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13
Q

what is the general role of sphincters in the esophagus

A

a sphincter insures bolus is transported in 1 direction: towards the stomach

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14
Q

the specific role of the upper esophageal sphincter?

A

initiates swallowing

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15
Q

the specific role of the lower esophageal sphincter?

A

prevents acid reflux from stomach into esophagus

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16
Q

what can persistent acid reflux lead to?

A

gastroesophageal reflux disease (GERD)

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17
Q

aside from GERD, what else could acid reflux from stomach into the esophagus lead to?

A

it can lead to ulceration & difficulty swallowing => fibrosis & stricture of lower esophagus

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18
Q

what is Barrett’s esophagus?

A

abnormal growth of intestinal-type cells (simple columnar) in the lower esophagus and its injured easily by stomach acid

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19
Q

what is a risk associated with Barrett’s esophagus

A

adenocarcinoma of esophagus with 3x greater incidence in males

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20
Q

if the esophageal hiatus in the diaphragm does not close entirely during development - results in ?

A

hiatal hernia

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21
Q

what “herniates” in a hiatal hernia?

A

portion of stomach can move into thoracic cavity

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22
Q

what signs could indicate you have a hiatal hernia?

A

difficulty swallowing, feeling “lump” in throat

reflux esophagitis, ulceration

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23
Q

the stomach (acidifies/alkalizes) food into viscous fluid known as _______

A

acidifies, chyme

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24
Q

stomach produces (in general)?

A

enzymes and hormones

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25
Q

what are the longitudinal folds of the mucosa & submucosa called?

A

rugae

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26
Q

in what circumstance would you not be able to see rugae?

A

when the stomach is distended

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27
Q

so gastric pits are literally pits in the stomach. which pits would be deeper and which would be more shallow?

A

the gastric pits are deepest in the pylorus and shallowest in the cardia

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28
Q

the cardia of the stomach has what type of glands? what does it secrete

A

tubular glands with coiled end and it secretes mucous

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29
Q

what portion of the stomach is a primary contributor to gastric juice?

A

the fundus

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30
Q

the fundus has what types of glands?

A

simple tubular glands

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31
Q

shallow gastric gland pits in the fundus would have an abundance of what type of cell(s)?

A

parietal & chief cells

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32
Q

what has similar epithelium to the fundus?

A

the body of the stomach

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33
Q

what structure in the stomach has deep gastric pits with branched glands

A

pylorus

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34
Q

what would you find in the pylorus?

A

primarily mucus secreting with occasional parietal cell

G cells secreting gastrin

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35
Q

what are the layers of the gastric mucosa?

A

simple columnar
lamina propria
gastric glands
muscularis mucosae

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36
Q

the simple columnar cells in the gastric mucosa are similar to (but should not be mistaken as) what? and what do they secrete?

A

the simple columnar cells are similar to goblet cells because they secrete mucous on the surface lining of the cells

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37
Q

what are the contents of the lamina propria in the gastric mucosa?

A

loose CT with smooth muscle, lymphocytes, plasma cells, mast cells & fibroblasts

38
Q

how would you describe the muscularis mucosal layer of the gastric mucosa?

A

poorly defined inner circular layer
outer longitudinal layer of smooth muscle
occasionally an outermost circular layer (unique to GI)

39
Q

what type of connective tissue does gastric submucosa have and what four things would you find in it?

A

dense irregular collagenous CT with fibroblasts, mast cells, lymphoid elements, and Meissner’s plexus

40
Q

how many layers would you find in the gastric muscularis externa and what would they be?

A

3 layers of smooth muscle:

incomplete inner oblique
thick middle circular (forms pyloric sphincter)
outer longitudinal layer

41
Q

what is the gastric muscularis externa responsible for?

A

mixing the gastric contents

emptying the stomach

42
Q

what influences the stomach’s emptying rate?

A

chyme characeristics (e.g. viscosity, pH, lipid content, osmolality, caloric density)

43
Q

what the heck is gastric serosa???

A

covers external surface of stomach (per wiki = serous membrane)

44
Q

so gastric glands (of fundus) are simple tubular & consist of 3 segments:

A

isthmus - connects gland to base of gastric pit
neck
base

45
Q

what types of cells would you find along the gastric pits?

A

parietal, chief, mucous neck, enteroendocrine and regenerative cells

46
Q

regenerative cells are primarily located where along the gland/pit and what do they do?

A

regenerative cells are primarily located on the neck and isthmus
replace other cells in the gland, pit, & luminal surface

47
Q

what do gastric surface lining cells contain

A

they have apically located mucinogen granules

48
Q

what do surface lining cells secrete and what does it have a high concentration of

A

cloudy, thick, viscous mucous with high bicarbonate content

49
Q

what is the purpose of having high bicarb in mucous?

A

in the stomach, it confers acid protection, coats surface epithelium (~100 micrometers thick)

50
Q

do gastric surface lining cells live for a very long time?

A

they get renewed every 3-5 days

51
Q

mucous neck cells are located where?

A

located at necks of gastric glands

52
Q

mucous neck cells have
(short/long) microvilli
(apical/basal) mucous granules
(diminished/prominent) Golgi

and are (shorter/taller) cells than surface lining cells

A 
mucous neck cells have
    short microvilli
    apical mucous granules
    prominent Golgi
Shorter columnar cell than surface lining cells
53
Q

what do mucous neck cells secrete? what stimulates it?

A

soluble mucous (thinner than surface lining mucous) upon vagal stimulation

54
Q

what cells are pyramidal-shaped and are in the upper half of gastric glands?

A

parietal (oxyntic) cells

55
Q

what do parietal cells stain in H&E?

A

red-pink, they’re eosinophilic

56
Q

parietal cells secrete what two compounds?

A

hydrochloric acid (HCl) and gastric intrinsic factor

57
Q

what is gastric intrinsic factor used for

A

glycoprotein needed for the absorbtion of vitamin B12 in small intestine

58
Q

parietal cells have intracellular _________ _______, which can only be seen by EM

A

tubulovesicular system

59
Q

where would you find intracellular canaliculi and what are they?

A

they are in parietal cells

intracellular canaliculi - deep invaginations of the apical plasma membrane lined by microvilli

60
Q

when parietal cells are stimulated to secrete HCl, number of microvilli (increases/decreases)
complexity of tubulovesicular system (increases/decreases)

A

number of microvilli increase

complexity of tubulovesicular system decreases

61
Q

what two molecules stimulate HCl secretion?

A

acetylcholine and gastrin

62
Q

what increases the effects of acetylcholine & gastrin on parietal cells?

A

histamine binding to histamine H2 receptors

histamine produced by enterochromaffin-like cells in lamina propria around gastric glands

63
Q

why do people take anti-acid drugs like cimetidine?

A

inhibits histamine-dependent acid secretion (drops acid secretion)

64
Q

why do people take anti-acids like omeprazole?

A

because it binds to H+, K+-dependent ATPases and inactive acid secretion completely

65
Q

describe how carbon dioxide (either from blood/parietal cells) ends up getting picked up by capillaries?

A

carbonic anhydrase combines CO2 with OH- ions => carbonic acid => bicarbonate = H+
bicarbonate diffuses out of cell and gets picked up by capillaries

66
Q

what does the uptake of bicarb affect?

A

affects blood and mucous pH on the surface

67
Q

what cells are pyramidal-shaped and in the lower half of the fundic glands?

A

chief (zymogenic) cells

68
Q

what do chief cells stain in H&E?

A

blue/basophilic

69
Q

what do chief cells secrete?

A

pepsinogen (zymogen form of pepsin)
rennin precursors
lipase precursors

70
Q

chief cells have a lot of (basally/apically) located rER
(supranuclear/subnuclear) Golgi
(basal/apical) secretory granules (zymogen)

A

chief cells have a lot of basally located rER
supranuclear Golgi
apical secretory granules

71
Q

enteroendocrine cells belong to a population of what type of cells?

A

diffuse neuroendocrine cells aka APUD cells

72
Q

diffuse neuroendocrine cells (DNES) are also called?

A

APUD cells (amine precursor uptake & decarboxylation cells)

73
Q

how many different types of enteroendocrine cells are there and how many hormones do each secrete?

A

there are greater than a dozen types, each type only secretes one hormone

74
Q

gastric juices contain?

A

water, HCl, mucus, pepsin, lipase, rennin, & electrolytes

75
Q

what is the acidity of gastric juice?

A

pH = 2.0

76
Q

what gets activated by gastric juice and how does it facilitate it?

A

pepsinogen -> pepsin

gastric juice catalyzes the partial hydrolysis of proteins

77
Q

gastric secretions are regulated by what?

A

they are regulated by the vagus nerve and hormones

78
Q

secretin:

who secretes it
when is it secreted
what does it stimulate?

A

duodenum secretes secretin @ pH < 4.5
stimulates pancreatic secretion of HCO3 & fluid
chief cells secrete pepsinogen

79
Q

gastrin:

who secretes? what does it stimulate?

A

G cells in pylorus (small G17) & duodenal mucosa (large G34) secrete gastrin

stimulates HCl secretion

80
Q

somatostatin:

who secretes? what does it affect?

A

D cells of pylorus & duodenum
inhibits gastrin
indirectly inhibits HCl secretion

81
Q

Gastric inhibitory peptide (urogastrone)

who secretes? what does it affect?

A

cells in duodenum & jejunum

directly inhibits HCl secretion
stimulates insulin release

82
Q

hormone produced in duodenum & jejunum,

stimulates gallbladder contraction when fat is in small intestine

A

cholecystekinin (CKK)

83
Q

hormone released cyclically (~ every 90 minutes) during fasting from cells in upper GI tract

A

motilin

84
Q

what types of people are more likely to get gastritis?

A

more common in middle-aged/older individuals

85
Q

what is the typical etiology of gastritis?

A

unknown

86
Q

what is the range of problems gastritis could lead to?

A

superficial or affect the entire thickness causing mucosal atrophy

87
Q

what is abnormal in patients with Zollinger-Ellison syndrome?

A

patients have gastrin secreting tumors (ups HCl), hypertrophy of fundus => stomach acid, diarrhea

88
Q

Gastric/peptic ulcers are defined as what

A

areas of mucosa (gastric/duodenal) destroyed by gastric secretions

89
Q

in what parts of the GI system are peptic ulcers commonly found?

A

cardiac & pyloric regions & first part of duodenum

90
Q

what are causes of gastric ulcers (6 possible causes)

A 
excess HCl secretions
nervous irritation 
decreased vascular supply
reduced mucus secretion
infection (Helicobacter pylori)
NSAIDS (e.g. aspirin)
91
Q

possible treatments for ulcers?

A 
antibiotics
stress management
eliminating alcohol
eliminating asprin/NSAIDS
eliminating cigarette use 
antacids or drugs that inhibit gastric secretions
92
Q

what are the infection phases of H. pylori?

A

active phase - H. pylori increases gastric pH by producing ammonia via urease

stationary phase - bacteria attach to fucose (< real thing) containing receptors on mucus cell surface in pylorus
bacteria releases proteases that kills surface cells

colonization phase - bacteria detach & replicate in mucus blanket

Histo Exam 3 (6 decks)

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