Which parts of the oral cavity are keratinized stratified squamous epithelium?
gingiva, hard palate, dorsal surface of tongue
What do ameloblasts secrete & what do odontoblasts secrete? where are they found?
3 Major salivary glands & what type of gland are they?
Sublingual - predominant mucous
Submandibular - mixed
Parotid - serous
Ducts of major salivary glands:
Intercalated duct - secrete bicarbonate, absorb Cl- from acinar product
Striated duct - reabsorption of Na ion from primary secretion, addition of potassium to secretion
Excretory interlobular duct - final duct
What parts of esophagus have what types of muscularis externa? Where are adventitia & serosa layers found?
Upper - striated muscle
middle - striated & smooth
lower - smooth muscle
adventitia - upper & middle
serosa - lower
What is an important part of the esophagus for disease (such as Barrett's esophagus? Why?
esophago/gastric junction; dramatic change of epithelium from stratified squamous --> columnar
What are the 2 types of plexi & where are they found?
Meissner's plexus - submucosal
Auerbach's plexus - myenteric
Why are so many mucus glands found in esophago-gastric junction?
for acidity of stomach to be neutralized
What 2 things protect the squamous epithelium of esophagus from exposure to gastric acid?
esophago-gastric junction & esophago-gastric muscular sphincter
What can heartburn (reflux of gastric acid into lower esophagus) lead to?
changes of stratified squamous epithelium to gastric epithelium (columnar)
cells of gastric gland epithelium?
-mucous neck cells (soluble mucus)
-parietal cells (HCl)
-chief cells (pepsinogen)
-Enteroendocrine cells (hormones)
How can a gastric ulcer form?
helicobacter pylori infection can damage stomach mucosa's protective layer, acidic gastric content damages mucosa epithelial cells/lamina propria die -->ulcer
How can a gastric ulcer cause death?
ulcer can perforate stomach wall & gastric contents can pour into peritoneal cavity
How can atrophic gastritis lead to pernicious anemia?
lack of parietal cells so lack of intrinsic factor (needed to absorb B12)
What are the structures responsible for the small intestine's increased surface area?
1. plicae circulares (folds of submucosa)
2. villi (folds of mucosa)
3. crypts of lieberkuhn (glands)
4. microvilli w/ glycocalyx
absorptive cell w/ microvilli (brush border) found near top of villus in small intestine
allergic to gluten - leads to flattening of jejunal surface or loss of villi
In the large intestine, do surface cells have glycocalyx & digestive enzymes?
no digestive enzymes but still glycocalyx
mucosa is lost w/ ulceration & destruction of absorptive epithelium impairing water resorption from colonic contents resulting in watery diarrhea & bleeding
Hirschsprung's disease (congenital megacolon)
defecation is not possible; infants & children; segment of lower rectum is devoid of ganglion cells
Where is appendix & what types of cells does its epithelium have?
bw large & small intestine
absorptive cells & M cells
Other than esophagus to gut, where else is abrupt change in epithelium?
rectum -> anal canal (simple columnar -> stratified squamous)
Where are hepatic stellate cells? What is it a storage site for?
in space of disse - bw endothelial cells & microvilli of hepatocyte
aka ito cells
What can happen w/ ito cells?
transform to myofibroblasts & produce high level of collagen
-collagen type 1 (cytokines produces by hepatocytes stimulate production) deposited in space of Disse leads to fibrosis & alteration of portal venous blood flow (portal hypertension)
How does liver cirrhosis occur?
progressive hepatocyte destruction due to alcohol toxicity, viral infection & liver disease
-death of hepatocytes -> scarring
-collapse of normal architecture & increased production of fibrocollagenous tissue
(massive collagen production)
What are 3 ways of describing structure of liver? Most clinically important?
1. classic lobule - hexagonal, axis = central vein
2. portal lobule - triangular, axis = interlobular bile duct
3. liver acinus - eleptical, axis = distributing vessels
-liver acinus most clinically imp. bc looks at blood flow to liver
zones of liver acinus:
zone 1 - first to receive nutrients or toxins (most O2)
2 - between
3 - last to receive nutrients & toxins (most affected if O2 decreases)
Major functions of gallbladder?
concentrates & stores bile (stored by taking H20 away), absorption of water & electrolytes
What can be caused by large gallstones?
-obstructive jaundice - obstruction of bile duct
-cholecystitis - obstruction of cystic duct
What 2 hormones are under control of exocrine function by enteroendocrine cells in duodenum?
seretin - stimulates biocarbonate ion secretion
CCK - stimulates enzyme secretion