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4 layers of GI tract
mucosa, submucosa, muscularis, serosa
___________ layer of GI tract : epithelium, lamina propria and muscularis mucosa
mucosa
___________ layer of GI tract : dense connective tissue, vessels + n, glands, Meissner's plexus
submucosa
epithelium of esophagus mucosa
nonkeratinized stratified squamous epithelium
epithelium of stomach mucosa
monomorphous simple columnar epithelium
epithelium of intestine mucosa
polymorphous simple columnar epithelium
______________ of mucosa has loose connective tissue, n, leukocytes and glands
lamina propria
muscularis mucosae of gi tract consists of
smooth m fibers
stratified squamous epithelium is ________ mucosa, monomorphous columnar epithelium is _____________ mucosa and polymorphous columnar epithelium is ________ mucosa
protective secreting absorptive
where is secreting mucosa (monomorphous columnar)
stomach
where is protective mucosa (SSE)
oral, pharynx, esophagus, anal canal
where is absorptive mucosa (polymorphous columnar)
LI
Where is MALT
lamina propria of GI tract mucosa
Glands in lamina propria of mucosa in stomach vs intestines
gastric Lieberkühn
2 layers of muscularis mucosae of mucosa of GI tract
inner circular outer longitudinal
submucosa of which parts of the GI tract have glands
esophagus and duodenum
Muscularis propria of GI tract : in bw 2 layers there is
Myenteric Auerbach plexus
muscularis propria of stomach
inner circular, outer longitudinal and extra oblique layer
m fibers of muscularis propria of GI tract
striated m fibers in upper 1/3 smooth m fibers in 2/3
serosa vs adventitia cover
seroa - intraperitoneal adventitia - extraperitoneal
layers of GI tract serosa
subserous inner layer mesothelium (SSE)
why does esophagus look stellate
longitudinal folds in lumen (for distention)
mucosa of esophagus
nonkeratinized stratified squamous epithelium
submucosa esophageal glands secrete
acid mucins
covering of adventitia/serosa
adventitia until pierces diaphragm, then serosa
gastro-esophageal junction (z line)
non-keratinized stratified squamous to simple columnar
role of gastro-esophageal jxn
functional sphincter to prevent reflux
what is the gastro-esophageal jxn a location of?
patho changes (barrett's, epidermoid carcinoma)
electrolytes, pepsinogen, hydrochloric acid, B12, and mucins are in
gastric secretions
which part of stomach makes chyme
body
_______ is a narrow region at the gastroesophageal jxn
cardia
stomach is divided histologically in 3 regions based on glands
cardiac glands, fundic glands and pyloric glands
rugae of stomach are made of
mucosa and submucosa
mamillated areas of stomach ->
gastric pits
lining epithelium of stomach mucosa
simple columnar epithelium composed entirely of mucous cells (mucinogen granules)
structure of surface mucous cells of stomach
nucleus and golgi below mucous cup, tightly attached by occluding jxns, w. microvilli and covered by glycocalyx
______ is high alkaline (entrapped bicarbonate ions) + insoluble + has PGE2
mucus of stomach
what is special about gastric lamina propria
no lymph tissue
which stomach glands are very long and have 5 diff cell types
fundic glands
_________ cells of fundic glands are in bw neck of gland w/ gastric pit
stem
mucous neck cells of fundic gland
short + spherical, secrete less mucinogen (induced by vagal stimulation)
chief zymogenic cells of fundic gland secrete
pepsinogen and gastric lipase
parietal oxyntic cells of fundic gland role
release hydrochloric acid and gastric IF
parietal oxyntic cells of fundic gland structure
pyramidal cells w/ intracell canaliculi w/ tubulovesicular system bordering
number of microvilli and the abundance of vesicles of the tubulovesicular system of parietal oxyntic cells vary with
Hcl secretory activity of parietal cells (active secretion = more microvilli, less system)
how does tubulovesicular system contribute to acid secretion
stores plasma membrane to increase surface + proton pumps for acid production
parietal cells of fundic glands contain important quantities of
carbonic anhydrase
parietal cells of fundic glands are 3 receptors:
gastrin (HCl secretion) histamine (Ach + gastrin effects Ach (gastrin secretion)
__________ are cells that are found everywhere in fundic gland and secrete paracrine + endocrine effects
DNES
open vs closed enteroendocrine cells of fundic gland
closed - usually on basal lamina
open - extensions exposed to gland lumen
how are enteroendocrine cells identified
immunohistochemical stains
gastrin, serotonin, histamine, PP (pancreatic polypeptide) and VIP (vasoactive intestinal peptide) are secreted by
enteroendocrine cells of fundic gland
How are pyloric glands different from the gastric glands and cardiac glands?
deeper pits and highly convoluted
unlike fundic glands, pyloric gland epithelia consist only of
mucous cells
compared to the fundic gland, pyloric gland have no _______ cells but have far more _______-
chief cells G cells (enteroendocrine)
in SI, digestion is facilitated by
enzymes + alkaline buffer
what has plicae circulares/valves of Kerckring, villi and microvilli?
SI
what decreases the velocity of chyme movement
valves of kerckring
_______ consist of core of loose connective tissue covered by simple columnar epithelium, w/ cap loops and lacteal
villi (of SI)
role of smooth m cells of villi
contract to force lymph from lacteal to lymph vessel
where are microvilli found
absorptive cells of the small intestine
function of occluding jxns of enterocytes
barrier bw intestinal lumen and epithelial intercell compartment, forces digestive products to cross brush border
lateral domain of enterocytes contain
occluding jxns and lateral infoldings
secretory fxn of enterocytes
synthesis of glycoprotein enzymes by Golgi
abundant organelles of enterocytes
Golgi (secretion), sER (absorption of fats), elongated mitochondria
digestion, absorption, re esterification and chylomicron formation are roles of
enterocytes (absorptive cells)
what enzymes digest carbs in enterocyte
amylase
digestion of proteins by enterocyte
pepsin in stomach -> peptidases of enterocytes
digestion of lipids of enterocytes
triglycerides broken down + emulsified by bile salts -> enterocyte re-esterified to triglycerides -> lacteals -> liver
goblet cell # increases from which locations of GI tract
duodenum to ileum
fxn of goblet cells of SI epithelium
secrete mucus by mucinogen
DES cells of SI epithelium
produce paracrine and endocrine hormones, regulating secretion + motility
where are DES cells located
SI, base of Lieberkuhn crypt, sometimes to surface of intestinal villi
CKK, GIP, VIP and secretin are found in which cells of SI epithelium
DES cells
function of M(microfold) cells of SI epithelium
transport antigens in intestines to immune cells in their recesses
paneth cells
in crypts of epithelium, regulates flora
lamina propria + submucosa of ileum have
Payer's patches
Brunner's glands of submucosa of duodenum
protects SI by neutralizing acid in chyme
what are the cells in intestinal m. externa that are pacemarker cells for motility
interstitial cells of Cajal
2 kinds of m contraction occur in SI
segmentation (circ layer) and peristalsis (long layer)
differences of duodenum
contain duodenal papilla of Vater and Brunner's glands in subumucosa
differences of jejunum
villi narrower, more goblet cells
___________ has no villi but many crypts of Liuberkuhn
colon
collagen table, pericryptal fibroblast sheath, GALT are in what of the colon
lamina propria
colon's lamina propria has no
lymph cap
function of collagen table of colons' lamina propria
regulates water + electrolyte transport
outer longitudinal layer of muscularis externa of colon contains
3 m fascicles = teniae colie => haustra coli (sacculations)
what is different about the vermiform appendix in the caecum
uniform layer of longitudinal m of m externa
anal canal epithelium
non-keratinized stratified squamous epithelium, w/ anal columns and sinuses
why is submucosa of oral mucosa inconstant
ensures mobility of mucosa
epithelium of oral mucosa
stratified squamous epithelium, both keratinized, parakeratinized and non-keratinized areas
parakeratinized epithlium of oral mucosa
in areas of friction, immature (superficial cells don't lose nuclei like in keratinized)
The epithelium of the oral mucosa is composed of 4 types of cells, permanently present in this epithelium:
epithelial keratinocytes + epithelial non-keratinocytes (langerhans cells, merkel cells and melanocytes)
merkel cells
modified receptor epithelial cells in oral epithelium
2 layers of lamina propria of oral mucosa
superficial (papillary + loose connective tissue) and profound (dense connective tissue)
fordyce spots
angles of mouth have sebaceous glands without hair follicles
masticatory mucosa of oral cavity
fixed, keratinized stratified squamous epithelium without submucosa
lining mucosa of oral cavity
mobile, non-keratinized stratified squamous epithelium, w/ elastic fibers
specialized mucosa of oral cavity
on dorsal tongue, w/ tongue papillae and taste buds
nerves of oral mucosa
free n endings + end-bulbs of Krause + Meissner bodies on lips
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