GIT Histology Flashcards
4 layers of the GI tract walls
mucosa, submucosa, muscularis externa, and serosa
Components of the mucosa
Epithelium, lamina propria and muscularis mucosa
What type epithelium lining is in the GIT for protection
stratified squamous
Where is stratified squamos epithelium found
in the pharynx and esophagus
What type epithelium lining is in the GIT for secretion
Simple columnar
Where is simple columnar epithelium found
Stomach and intestines
Responsible for IgA production, is found in the lamina propria
GALT (gut-associated lymphoid tissue
What is the function of the muscularis mucosa
confers some motility to the
mucosa and facilitates discharge of secretions from glands
Function of the submucosa
houses the larger blood vessels and
mucous-secreting glands
2 layers of the muscularis externa
An inner
circular and an outer longitudinal
Describe the muscualris externa in the upper 1/3 of the esophagus and the lower 1/3
The muscle is striated in the upper third of
the esophagus and smooth elsewhere.
Layer of the epithelium that doubles to form mesentery
Serosa
Location of Auerbach’s plexus
between the 2 muscle layers of the muscularis externa
Plexus that is affected in Hirschsprung disease
Auerbach’s plexus ( deficiency of terminal
ganglion cells in the ganglia that affects digestive tract mobility)
Location of intrinsic innervation in the GIT
within the walls of the GI tract
What makes up the extrinsic innervation of the GIT
parasympathetic
(stimulatory) and sympathetic (inhibitory) axons
Function of sensory fibers accompanying the parasympathetic nerves in the GIT
mediate visceral reflexes and sensations, such as hunger and rectal fullness
Location of Brunners glands
Submucosa od duodenum
Location of Peyer’s patches
Mucosa of Ileum
Location of crypts of Lieberkuhns
Small and large intestines
Location of gastric glands
Mucosa of stomach
Section of the GIT that lack villi
Large intestines
Location of plicae
Small and large intestines
Location of most developed plicae
Jejunum
Location of M cells found over
lymphatic nodules
and Peyer’s patches
Ileum
Function of Mucous cells
Secrete mucous; form protective layer against
acid
Function of Chief cells
Secrete pepsinogen and lipase precursor
Function of Parietal cells
Secrete HCl and intrinsic factor
Function of EE cells
High concentration of cells that secrete
cholecystokinin and secretin
Function of Paneth cells
Contains granules that contain lysozyme
Function of Goblet
Secrete acid glycoproteins that protect mucosal
linings
Macrophage-like antigen-presenting
cells thatare present in the epithelial lining
Langerhans cells
Function of intrinsic factor
necessary for absorption of vitamin B12
Lack of absorption of Vitamin B12 leads to
pernicious anemia
How is pepsinogen converted to pepsin
By acid
Three substances that activate secretion of parietal cells
Ach, HCl increase by gastrin and histamine
What is pepsinogen stored in in cheif ells
zymogen granules
Which cell types are basophilic
Chief cells
Which cell are acidophilic
Parietal cells
What factors increase rate of mucous secretion
cholinergic stimulation, chemical
irritation, and physical irritation
Function of Brunners glands
neutralize chyme from the stomach by neutral or alkaline mucous secretions
From what two organs do the duodenum receive digestive enzymes and bicarbonate
pancreas and liver (bile)
Function of enterocytes
Participate in the
final digestion steps and they absorb the digested food
What nerve innervates the external anal sphincter
Pudenal nerve
What is the Valsalva maneuver
Voluntary increase in intra-abdominal pressure
