LECTURE - GI System Flashcards
GI glands have two main functions
- digestion of food
- protection of the GI mucosa
acinus
a spherical mass of cells with a lumen at the center
mucosa of esophagus
non-keratinized squamous epithelium
lamina propria of esophagus
blood vessels, inflammatory cells, mucus glands
muscularis mucosa of esophagus
peristalsis
- small layer
muscularis propria
bigger muscle layer - responsible for lots of peristalsis
submucosa
supportive tissue = mucus glands, blood vessels, nerves
synonymous with serosa for esophagus
adventitia (covers esophagus)
- loose connective tissue - lacks true serosa for most of its length
- doesnt need it like colon does for ex (‘floating’)
glands in esophagus
- submucosal mucus glands with cuboidal lined ducts running up the luminal surface
- glands resemble salivary and Brunner’s glands
- gastric glands may be metaplastic or just related to location
- can find heterotopic pancreas tissue
- intestinal glands or goblet cells are indicative of metaplasia and Barrett esophagus
a mixed endocrine and exocrine organ that both digests food and secretes hormones into the bloodstream
stomach
stomach histology
- simple columnar (foveolar epithelium)
- gastric pits
- glands beneath the pits
Paneth cells
secrete antimicrobial substances
- mainly small bowel and right colon
Brunner’s Glands
- unique to duodenum
- submucosal
- secrete alkaline mucus fluid that neutralizes stomach acid so it doesn’t burn a hole in the duodenum
colon
- main function = absorption of water
- consists of long tubular crypts (Crypts of Lieberkuhn)
- goblet cells are abundant
protein synthesis in liver
- albumin
- prothrombin
- fibrinogen
- lipoproteins
glandular epithelial cancer
adenocarcinoma
function of the small bowel
absorption of nutrients
- need massive SA; long and has tiny villi that carpet the lumen
surgeries which reduce the length of mal intestine
can lead to problems with maladsorption
- short gut syndrome
where are goblet cells found?
throughout small and large bowel
two main entities of inflammatory bowel disease
Chron’s disease
Ulcerative colitis
Crohn’s disease
- can affect entireity of GI tract
- most typically affects terminal ileum
Ulcerative colitis
- limited to colon
- tycially afects rectum and distal colon but can spread contiguously
function of the salivary glands
- digestion (amylase)
- lubrication (mucin)
- immunologic (IgA)
types of salivary gland secretions
- serous
- mucinous
parotid gland
- purely serous
- contributes 25% of saliva
- branched acinar
- secretions contain amylase and IgA
serous acini
- watery (pink) secretions = enzymes and Abs
- pyramidal shaped cells with basophilic cytoplasm
mucinous acini
- secrete viscous (clear) mucus
- cuboidal to columnar cells with pale pink cytoplasm and oval nnucle towards the base of the cells
submandibular gland
- serous and mucinous
- 70% of saliva
- branched tubuloacinar pattern
- serous deminlunes secrete lysozyme
lysozyme
the body’s natural antimicrobial enzyme
sublingual
- mainly mucinous
- branched tubuloacinar gland
- produces lactoferrin (antimicrobial)
- contributes 5% of saliva
interlobular, intralobular, intercalated ducts run through this organ
pancreas
exocrine pancreas
compound acinar glands
- trypsinogen
- chymotrypsinogen
- carboxypeptidase
- ribonuclease
- deoxyribonuclease
- lipase
- amylase
- phospholipase A2
- elastase
endocrine pancreas
islet of Langerhans
- alpha: glucagon
- beta: insulin and amylin
- delta: somatostatin
- epsilon: ghrelin
- PP cells (gamma or F): pancreatic polypeptide
T or F. similar to pancreas, the liver has both endocrine and exocrine function
T!
- each hepatocyte contributes to both functions with no division of labour (UNLIKE pancreas)
- so hepatocytes are connected to both the blood supply and bile ducts
function of liver
protein synthesis
- albumin
- prothrombin
- fibrinogen
- lipoproteins
architechture of liver
- divided up into lobules
- central vein at center
- ptal triad at periphery
- between stacks of hepatocytes are sinusoids
sinusoids of liver are lined by
Kupffer cells = imobilized macrophages
this runs between hepatocytes and carry bile into ducts
bile canaliculi
what makes up the portal tracts
- heptic portal vein
- hepatic artery
- bile duct
- sometimes lymphatic vessel
T or F. occasionally, more than 1 bile duct is present per portal tract
T!
gallbladder
- simple columnar
- NO goblet cells
- no submucosa
- no muscularis mucosa or propria
- has muscularis externa
