4 layers of GI tube
mucosa, submucosa, muscularis externa, serosa/adventitia
mucosa of GI tube
epithelium w/basal lamina, lamina propria, muscularis mucosae
lamina propria of mucosa contains what/
connective tissue, glands, blood vessels, lymphatic tissue, lymphatic vessel endowment (segmental differences exist)
how does muscularis mucosae of mucosa increase surface area of GI tube?
contraction of muscle wrinkles the mucosa, this increases the surface area
describe the submucosa of GI tube
glands present in exophagus and duodenum, blood and lymphatics, submucosal or meissner's plexus
describe muscularis externa
two layers of smooth muscle, contraction=peristalsis, myenteric plexus
What is the submucosal (Meissner's) plexus
parasympathetic postganglionic neruons and sympathetic postganglionic fibers--regulates glands, blood flow, muscularis mucosae, and is sensory (mechano and chemo)
What is myenteric (Auerbach's) plexus?
located in muscularis externa, parasympathetic postgangionic neurons and sympathetic postganglionic fibers, controls peristalsis
What is achalasia?
damage to neurons in myenteric plexus causes constriction of LES. Limits passage of food into stomach
what layer of the esophagus has stratified squamous, nonkeratinized epithelium?
mucosa, submucosa, muscularis externa, serosa/adventitia
Where are cardiac esophageal glands found in the esophagus?
where are esophageal glands proper (seromucous) found?
What portion of muscularis externa is skeletal?
what portion of muscularis externa is smooth muscle?
adventitia or serosa? Thoracic or abdominal esophagus?
What is Barrett's esophagus?
acid reflux causes remodeling of lower esophagus to make metaplastic columnar epithelium with goblet cells. This mucous is to protect esophagus from the acid. Goblet cells appear blue with PAS/acian blue stains. Needs to be monitored for adenocarcinomas!
How will cancer spread in esophagus?
regions of the stomach
cardia, fundus, body, pylorus
Describe rugae of the stomach
longitudinal folds in undistended stomach, mucosa and submucosa form the folds
describe mucosa of the stomach
surface epithelium-simple columnar, mucous cells; gastric pits; glands empty into gastric pits; gland regions-isthmus, neck and fundus; lymphatic vessels (very few) deep in lamina propria and muscularis mucosae
muscularis externa of stomach
inner oblique layer of smooth muscle-only present in certain regions of the stomach; middle circular layer of smooth muscle-thickened at pylorus
three regions of gastric glands
three regions: isthmus, neck and fundus (base)
cells in isthmus region of gastric gland
surface epithelial cells-secrete mucus, parietal (oxyntic) cells-secrete HCL and intrinsic factor, stem cells
cells in neck region of gastric gland
mucous, more parietal and less chief cells, some enteroendocrine
cells in base region of gastric gland
chief (zymogenic) cells-secret pepsinogen, enteroendocrine cells, mucus, and few parietal cells
describe unique part of cardia portion of stomach
short gastric pits, long glands in lamina propria
unique part of pylorus
deep gastric pits, short glands, enteroendocrine cells (ex: G cells secrete gastrin)
how does stomach epithelium defend itself against stomach environment?
mucus and bicarbonate layer, surface cells secrete those things, cell renewal, alkaline tide, microcirculation, sensory nerves, prostaglandins
what is the pyloric sphincter?
thickening of muscularis externa-mainly inner circular layer- at the gastroduodenal junction
What structures increase surface area of small intestine?
plicae circulares (permanent circular folds of submucosa and mucosa), intestinal villi (processes of mucosa), microvilli
what are the signature features of gluten enteropathy (celiac sprue)?
enterocytes in disarray, villus atrophy, crypt hyperplasia, inflammation of lamina propria
mucosa of small intestine
basal lamina, mainly absorptive columnar cells with well-developed striated (brush) borders, goblet cells, intraepithelial T cells
lamina propria of small intestinal mucosa
loose CT, intestinal glands, many blood and lymphatic vessels, smooth muscle cells, leukocytes and plasma cells
what are the cells types of the intestinal glands (crypts of lieberkuhn)?
paneth cells (secrete lysozyme, defensins, TNF alpha), enteroendocrine cells, stem cells toward base
submucosa of small intestine
moderately dense CT, submucosal plexus, blood and lymph vessels
What are Brunner's glands?
duodenal glands- secrete mucus and human epidermal growth factor--located in submucosa
jejunum vs ileum
Wall of jejunum is thicker than ileum and jejunum is more richly vascularized; hence, jejunum is redder than ileum in a living person
where are Peyer's patches?
what are M cells
antigen transporting cells
plicae circulares is in?
small intestine mucosa
plicae semilunares where?
large intestine mucosa
absence of mucosa--large or small intestine?
Which has more intestinal glands? Large or small intestine
Where are goblet cells more numerous?
lamina propria of what GI area has no lymphatic channels?
where is the teniae coli?
What has lymphatic nodules in lamina propria and submucosa?
What is fecalith?
a monolithic poop stuck in your appendix. Can cause appendicitis
Rectum has what kind of folds?
what is a plicae transveraes recti?
transverse rectal fold in rectum
does rectum have teniae coli?
no, because they spread out and form a complete layer around muscularis externa
below pectinate line?
stratified squamous epithelium
where are anal cushions?
left lateral, right anterior, and right posterior
what hurts, internal or external hemorrhoid?
external. Internal are not on skin, no pain receptors
know about anal abscesses and fistula in ano
what is a false diverticula?
outpocketing of colonic wall--only involves mucosa and submucosa.
what is more likely to develop adenocarcinoma? Tubular or villous adenoma?
What is ulcerative colitis?
only large intestine. inflammatory bowel disease that increases lymphatic densitiy
can be mouth to anus, all layers of wall, fistula may form
agangliosis of myenteric and submucosal plexuses--always involves rectum, but may involve more proximal segments