Histo- digestive organs

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What is the largest glandular organ?: liver
What is the thin CT layer on the surface of the liver (except for the bare area)?: glisson's capsule
What is the hepatic lobule?: -found inside the liver arranged around blood vessels and the bile duct
-hexagonal structure
-at each angle there is a portal area
What is the portal area/portal triad/portal canal?: -is at each corner of the hexagon of the hepatic lobule
What three structures are found in the portal area/portal triad/portal canal?: -branch of the bile duct surrounded by simple cuboidal epithelial cells
-branch of the hepatic artery
-branch of the portal vein
What are liver parenchymal cells called?: hepatocytes
What is a hepatocyte?: -parenchymal liver cell contained on the outside of the liver sinusoids
-usually lined in cords
-is a cuboidal shaped cell
-contain microvilli on the surface pointing into the sinusoid
-contains large amounts of smooth and rough ER as well as golgi bodies
What is the space of disse in the liver?: perisinusoidal space that goes around the sinusoid, where the cytoplasm of the hepatocyte microvilli project into
What is a biliary canal?: combo of the bile canaliculi and the bile duct
What is the bile canaliculi?: -diamond shaped canal formed by two neighboring hepatocytes that connect to the branch of the bile duct in the portal area
-held together by zonula occludens(tight junctions)
What is the bile duct?: duct connected to the bile canaliculi in the liver that brings bile to the gallbaldder for storage
What is the blood flow from the portal area out of the liver?: -portal area
-into sinusoids
-into the central vein
-to hepatic vein
Does venous and articular blood mix in the sinusoids from the portal vein and the hepatic artery?: -yes
-75% venous and 25% arterial mix
-therefore cells require less oxygen than most cells to function
Why is the epithelium in the sinusoids of the liver discontinuous?: to allow rapid transport of material into and out of the cell
What does "discontinuous" epithelium mean?: there are spaces within the wall of the endothelial cells lining the sinusoid and there are holes in the underlying basement membrane of teh endothelial cells
What type of epithelium are sinusoids of the liver lined with?: simple squamous epithelium
What are kupffer cells?: phagocytic cells derived from blood monocytes that live in the lining of the liver endothelial cells
What does the hepatic lobule look like?: -6 sided structure
-center is central vein
-each corner has portal area
-blood flows from the portal areas to the central vein (outside - in)
-bile flows from the inside to the outside of the structure
-containes hepatocyte cords and sinusoids
What is the acinus of the liver?: -an oval shaped configuration
-the two distal the tips are located at a central vein
-the two closer tips are located at the portal systems
-is separated into zone I, II, III
In the acinus, where is zone I located? What is its function?: -closest to the portal areas
-drains blood first, recieves the most nutrients
Does zone II of the ascinus recieve the blood in the liver second?: yes
What is the main function of zone III?: detoxifies drugs and alcohol in the blood
What type of general functions does the liver have?: exocrine, endocrine and metabolic
What is the exocrine function of the liver?: makes bile and dumps it into the gall bladder
What is the endocrine function of the liver?: makes plasma proteins like albumin and carrier proteins for hormones like steroid hormones that go into the blood
What is the metabolic function of the liver?: cholesteol synthesis, fat and glycogen stroage, steroid hormone breakdown and drug detoxification
What layers are included in the tunica mucosa of tubular organs?: -epithelium
-lamina propria- loose areolar CT
-muscularis mucosae
What is in the tunica submucosa of tubular organs?: -is a mixture of loose and dense irregular CT
-contains large blood vessels and organized glands(mainly mucous secreting)
What is meissner's plexus?: autonomic ganglion in the tunica submucosa, is smaller than aurbach's
What is the tunica muscularis composed of?: -2-3 layers of mostly smooth muscle with some skeletal muscle
-arranged longitudinally in inner layers and transversly
What is auerbach's plexus?: autonomic ganglion important in contraction of smooth muscle (peristalsis) in the entire GI tract
What is the Tunica adventitia?: is a layer of CT only that is only retroperitoneal
What is the tunica serosa?: is intraperitoneal and consists of 2 parts
-CT and simple squamous epithelium
The simple squamous epithelium of the tunica serosa is called what?: mesothelium
In the esophagus, what type of tissue lines the tunica mucosa?: stratified squamous non-keratinized epithelium
In the esophagus,what is present in the tunica mucosa?: -folds in the basal region= papillae
-mucous glands in the lamina propria of the upper and lower parts of the esophagus, not the middle
-lymph nodules can also be present
-many capillaries in the upper layer of the lamina propria
In the esophagus,what is present in the tunica submucosa?: -contains large folds that allow the esophagus to expand
-mucous glands
In the esophagus, what is present in the tunica muscularis?: -inner and outer longitudinal layers of muscle w/ auerbach's plexus sandwiched between the two layers
In the esophagus, what type of muscle is present in the tunica muscularis of the upper esophagus, middle esophagus, and lower esophagus?: -upper = both layers are all skeletal
-middle = mix of both skeletal and smooth muscle
-lower = both layers are 100% smooth muscle
In the esophagus, where is the tunica adventitia and tunica serosa?: -T. adventitia through most of the esophagus length
-once the esophagus penetrates the diaphragm, it becomes T. serosa (mesothelium is simple squamous epithelium)
What is the function of the esophagus?: -carries food from the oral cavity to the stomach
-no digestion
-yes heat exchange, reason for lots of capillaries close the B. membrane
-mucous glands lubricate the esophagus for food and to buffer food contents
-lymphocytes may be present
In the stomach, what does the T. mucosa contain?: -gastric areas
-gastric pits
-gastric glands
What are the gastric areas of the tunica mucosa in the stomach?: mushroom shaped areas (folds) on the rugae
What are the gastric pits of the tunica mucosa in the stomach?: -crevaces in between the gastric areas as well as hols in the actual gastric area
-is an epithelial-lined area
What are the gastric glands of the tunica mucosa in the stomach?: epithelial lined gland the pit runs into that extends the depth of the tunica mucosa
What type of epithelium lines the stomach and pits?: simple columnar epithelium
What does the surface epithelial cells of the stomach look like?: -simple columnar epithelial cells
-all cells rest on the basal lamina and lines the gastric pit and gastric areas of the stomach
-contain short microvilli
-contain a junctional complex with many tight junctions
-contains mucous granules which contain the mucous product these cells make
-
What are the three divisions of the glandular epithelium of the stomach fundus/body?: -isthmus
-neck
-base
What types of cells are found in the isthmus of theglandular epithelium of the fundus/body of the stomach?: -surface epithelial cells
-parietal cells
What are parietal cells?: -cells filled w/ mitochondria
-cell surface is not smooth, has indentations called intercellular cannaliculi
-makes HCL
-makes gastric intrinsic factor
-stains pink, has fuzzy look
What are intracellular canaliculi of the parietal cells for?: increase surface area of the parietal cell so it can make hydrochloric acid
What does gastric intrinsic factor that is made by the parietal cell do?: binds vitamin B12
What does HCL that is made by the parietal cell do?: breaks down food
What cells are found in the neck of the glandular epithelium of the fundus/body of the stomach?: parietal cells
mucous neck cells
What do mucous neck cells look like?: -looks like a minature goblet cell
-makes mucous that is depositied into the lumen of the gland itself
What cells are found at the base of the glandular epithelium of the fundus/body of the stomach?: -parietal cells
-chief cells
What are chief cells?: -found only at the base of the gland
-pyramidal in shape
-blue stain, due to lots of RER
-makes protein, specifically pepsinogen
Describe the glandular epithelium of the fundus/body of the stomach.: -these are very long glands
-the galnds are 4x as long as the pits
-each has a lamina propria separating each gland that is nutritive
Describe the glandular epithelium of the cardiac/pylorus region of the stomach.: -gland depth is about equal to the depth of the pit
-gland epithelial cells are not specific, but resemble mucous neck cells
-glands and pits are surrounded by a lamina propria
What is a feature of the tunica submucosa of the cardiac/pylorus region of the stomach?: -makes the rugae
Describe the tunica muscularis of the cardiac/pylorus region of the stomach.: -is 3 layers of smooth muscle
-inner oblique layer
-middle circular layer
-outer longitudinal layer
**Auerbach's plexus is located between the circular and longitudinal layers
Does the cardiac/pylorus region of the stomach have a tunica serosa or tunica adventitia?: tunica serosa= CT and mesothelial layer
What are some functions of the stomach?: -general obvious functions
-prodigestion in chief cells
-HCL helps digest protein
-gastric intrinsic factor- helps intestine absorb B12
What are the divisions of the small intestine?: -duodenum = where digestion occurs
-jejunum = large plicae circularis
-ileum = small plicae circularis
What does the tunica mucosa of the small intestine include in general?: -intestinal crypts
-villi
-peyer's patches (only in the ileum)
What are intestinal crypts/glands in the small intestine?: -glands that villi lead into
-are very short as compared to the stomach
What are villi in the small intestine?: -fingerlike projections that are folds of the tunica mucosa
-each villus has a core of lamina propria
-each villi leads into an intestinal gland/crypt
What are peyer's patches?: -is a large collection of lymph nodules in the ileum
What is the epithelium of the small intestine composed of?: -absorptive cells
-goblet cells
-lymphocytes
What are the absorptive cells of the small intestine?: -most abundant cell in epithelium
-simple columnar cell w/ junctional complexes
-contain microvilli w/ striated border and glycocalyx on top
What is the glycocalyx?: glycoprotein and glycolipid layer on the surface of microvilli of absorptive cells
What do goblet cells secrete? Where are they found?: -mucous
-seen near the striated border of the tunica mucosa
How do lymphocytes arrive in the epithelium of the small intestine?: -they migrate through the basement membrane and junctional complexes of the lamina propria
-seen in the middle of the tunica mucosa inbetween absorptive cells
Where and what are paneth cells?: -seen at the base/bottom of the glands
-contain an antibacterial substance called lysozyme
-contain bright red granuls
What does the tunica submucosa of the small intestine contain?: -plicae circulares
-brunners glands (only in the duodenum)
What are plicae circulares?: -large folds of the tunica submucosa
-present in all three areas of the small intestine
-highly developed in the jejunum
What are brunner's glands?: -in the duodenum only
-mucous producing gland that neutralizes the acidic pH of the stomach so that the enzymes of the pancreatic duct can function
What does the tunica muscularis of the small intestine contain?: -2 layers of smooth muscle
-inner circular layer
-outer longitudinal layer
Where is the tunica serosa in the small intestine? Where is the tunic adventitia in the small intestine?: -serosa = 1st part of duodenum, all of jejunum and ileum
-adventitia = 2nd and 3rd part of duodenum because it is retroperitoneal
What is the function of the small intestine?: -digestion and absorption
-neutralization of the acidic pH from the stomach
-glycocalyx functions in immunology
What is the general structure of the large intestine?: -no villi
-no plicae circularis
-yes tenia coli= regionalized compartments of longitudinal muscle
What does the tunica mucosa of the large intestine contain?: -simple columnar epithelial cells
-lots of goblet cells, has the highest ratio of goblet cells to epithelial cells
-goblet cells function to lubricate feces
What does the tunica submucosa of the colon contain?: -lymph nodules
-folds that are not "true", folds are made by haustra coli not submucosa
What does the tunica muscularis of the colon contain?: -2 layers of smooth muscle
-inside circular layer
-outside longitudinal layer called teniae coli
Does the colon have tunica adventitia or tunica serosa?: both
-adventitia is retroperitoneal
-serosa is intraperitoneal
What is the function of the colon?: -very little digestion occurs here
-water and electrolytes are absorbed here
-small hormonal activity and lubrication by the goblet cells

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