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