HE 28-30 GI Flashcards
(38 cards)
General characteristics of oral mucosa and three major types
General: THICK epithelium and lamina propria (lip)
functions as physical/immunological barrier, taste
- Lining (non keratinized stratified squamous)
- inner side of lips/cheeks, floor of mouth and soft palate - Masticatory: Gums, hard Palate
- Gustatory: Taste buds
Submucosa Properties and Innervation
Supplies and drains blood and lymphatics to and from mucosa
- can be folded to increase SA
- can have submucosal glands (ESOPHAGEAL GLANDS) for lubrication and ducts to lumen
SUBMUCOSAL PLEXUS: visceral motor and sensory fibers, postganglionic parasympatheic, interneurons
- part of enteric nervous system
- innervates teh flands and smooth muscle of the mucosa
Muscularis externa properties and inntervation
CM: inner circular layer of smooth muscle
- thickens locally for sphincters
- compresses lumen
LM: outer longitudinal smooth muscle
-shortens tube
MYENTERIC PLEXUS: between CM and LM
- also part of enteric nervous system
- innervates muscularis externa
- Neural tube or crest???
Proximal 1/3: all skeletal muscle
Distal 1/3: ALL SMOOTH MUSCLE
Serosa and Adventitia
Intraperitoneal: completely lined by serosa
-serosa: visceral peritoneum->mesothlial layer, simple squamous (from mesoderm) and bit of loose CT
Retroperitoneal
-adventitia: loose CT binding to body wall
Mucosa
-epithelial: strat sq
lamina propria with diffuse lympoid tissue
-muscularis mucosa: contractile smooth muscle to dislodge food
Gastroesophageal Jxn and CC
NO anotomical sphincter
-SHARP TRANSITION from stratified squamous to simple columnar.
GERD: weakness of esophageal sphincter causes reflux of stomach juices into this area, causing inflammation of esophageal mucosa, shest pain, irreversible metaplasia of esophageal mucosa
Stomach: main function and overview of layers
Initial protien digestion, mixing of food and gastric juices (glands)
lumen will contain Chyme mix and gastric juices.
Main layers: Mucosa: gastric glamds SM: rugae folds ME: three layers serosa: continuous
Layers of Gastric Glands and cell components in stomach
gastric pit: surfece mucosa cells (insoluble thick mucosa)
Gastric Gland
- Isthmus: Parietal cells
- Neck: Neck Mucous cells (soluble thin mucous), stem cells, parietal cells
- base of gland: chief, parietal, neck mucous, enteroendocrine`
Parietal cells location and seven main features/functions, and clinical correlation
located in the gastric glands
“fried egg cell” large acidophilic cytoplasm
1. acidophilic due to high mitochondria and folded membranes (increased SA for secretion)
2. Microvilli
3. Secrete HCL
4. Secrete Intrinsic Factor- binds to VitB12 for later absorbtion in Ileum
5. Intracellular Cannoniculus- deep invaginations of PM
6. Tubular Vesicles: cytoplasmic resivours of unit membranes and proton pumps
7. change surface area: secrete into intracellular cannoniculus.
-resting: IC shallow
-active: IC fuse with TV (deeper)
damage to mucosa (peptic ulcer) or drug supression of parietal cells leads to pernicous anemia from decreased intrinsic factor
Cheif cells location and function
only at base of gland
secrete pepsinogen to initiate protien digestion
- Basal RER (basal half of cell basophilic (dark)
- apircal zymogen granules with pepsinogen that are secreted into the lumen
- low pH activates pepsinogen to pepsin
Enteroendocrine Cells of stomach
Small cealr staining cytoplasm like K cells
- basal granules: contain Regulatory hormones
- Gastrin: G cells\
- somatostatin
these release hormones basally into the fenestrated capillaries of the LP
Gastric Glands of Cardia and Pylorus of stomach
Cardia: cone at entrance, prodominately mucous cells, provide protection
-wide gastric pits, mucous cells at base similar to suface mucosa cells
same at pylorus except:
Pylorus: cone at exit, no esophageal mucosa but image may show duodenal mucosa
Gastric glands of body and Fundus of stomach
surface mucosa cells limited to gastric pits
-pareital and chief cells abundant
Submucosa of Stomach
evaginations of submucosa form folds- RUGAE
-can flatten out to allow expansion
Muscularis Externa of stomach
additional innermost layer of oblique muscle
-fxns to twist and mechanically break down food
oblique, circular, longitudinal
MYENTERIC PLEXUS
Pyloric Sphincter of Stomach
at exit, condituous with circular muscle in ME
-relaxation of sphincter and contraction of ME allow for gastric emptying
Serosa of Stomach
Simple squamous to cuboidal
- small amounts loose CT
- covers stomach
- secretes small amounts os serous fluid into peritoneal cavity for lubrication
Small Intestine Overview
duodenum, jejunum and ileum
-neutralize acidic chime from stomach
-finish digestion and absorb nutrients
immune defense
Mucosa of Small Intestine Overview
Epithelium
- goblet, paneth, enteroendocrine, Mcell
- simple columnar with microvilla
- evaginates into villi
- invaginates into short intestinal glands
LP- lymphoid nodules and lacteals
muscularis mucosa
-contractions milk glandular secretions, some smooth muscle extend into villi, and contractions pump lymph down villi
Enterocyte of Small intestine
Main cell of SI
- secrete and absorb
- tall microvilli
- glycocalyx present with digestive enzymes on microvilli, secreted by enterocyte
- connected via tight junctions
Goblet calls of Small intestine
secreting mucous to protect epithelium from self digestion
- H&E clear appearance
- PAS: dark: apical carb rich mucinogen granules
Paneth cell of small intestine
ONLY IN JEJUNUM AND ILEUM
- bases of intestinal glands
- apical acidopholic granules with antimicrobial compounds for non specific innate immunity
Enteroendocrine cell of Small intestine
Clear staining cytoplasm
-basal granules: regulatory hormones- CCK (I cell), secretin (S cell) somatostatin
varied hormonal control for gland secretion and guy motility
- hormones secreted basally into capillaries of lamina propria
- what type of cap?
M cell of Small intestine
most abundant on ileum
- on top on lymphoid nodules
- NO microvilli: not absorbtive
- relay luminal antigens to lymphocytes below
