unit 12 Flashcards
exocrine
release secretory into ducts or lumen
endocrine
release secretary into circulation
serous glands
pyramidal shape with base on basal lamina
round nucleus
joined by junctional complexes
usually organized as acinus
mucous glands
cuboidal to columnar with nuclei pushed towards base, oval nuclei at base, secretory drops at apex
organized as tubules
viscous mixture of glycoproteins
myoepithelial cells
derived from epithelial cells
located between basement membrane and epithelial surface
flat with long processes around secretory element
what do myoepithelial cells contain
keratin and myofilaments
what are the minor salivary glands? where are they located?
mucosal, lingual, buccal, palatine
in the submucosa of the oral cavity
what is saliva
hypotonic solution that functions to lubricate and cleanse the oral cavity
what does saliva do?
reduces bacterial flora by way of lysozymes, lactoferrin, peroxides, histine rich proteins, and IgA
initial digestion of carbs by salivary amylase
assists in the process of taste
what types of glands are in the parotid gland?
serous ONLY
what types of glands are in the submandibular gland? sublingual?
mostly serous, some mucous
mostly mucous, some serous
salivary gland, from acinus
acinus to intercalated duct to striated duct to excretory duct
intercalated ducts
cuboidal epithelium that acini open up into
secrete HCO3, absorb Cl
striated ducts
simple cuboidal to columnar
union of several intercalated ducts to form interlobular duct
radial striations of inholdings of basal plasma membrane and mitochondria
secrete K and HCO3, absorb Na
excretory ducts
interlobular ducts in septa, stratified cuboidal or columnar
parotid gland facts
no centroacinar cells
longer intercalated ducts comparatively
fat cells
many plasma cells and lymphocytes that secrete IgA
submandibular gland facts
mostly serous, some mucous
striated duct more developed than others
sublingual gland facts
mixed secretion with mostly mucous and some serous demilunes
interlobular duct system is not well developed
what is the pancreas
a gland that lies posterior to the stomach
produces enzymes that aid in digestion
produce sodium bicarb which buffers stomach acid
empties contents into duodenum
pancreatic ducts/glands
compound acinar gland with no striated ducts
contains centroacinar cells
thin capsule with septa that divide into lobules
exocrine pancreas cells
highly polarized with rER, Golgi, and mito packed into basal part
apical cytoplasm, packed with zymogen granules
tight junctional complexes along apical membrane
what does the exocrine pancreas secrete
15 or more enzymes or proenzymes
pancreatic lipase - fat digestion
pancreatic amylase - carb digestion
trypsin - protein digestion
DNAase and RNAase
what regulates the exocrine pancreas
hormones - secretin and cholecystokinin
vagus nerve
exocrine pancreas cells
simple pyramidal serous epithelial cells
narrow luminal surface
broad basal surface
central acinar cells
endocrine pancreas
islets scattered among acini
reticular fibers
fenestrated capillaries
more numerous in body and tail
5 different hormone secreting cells
hormone producing cells in endocrine pancreas
alpha - producing glucagon
beta - manufacturing insulin
delta - manufacturing somatostatin
PP - secrete pancreatic polypeptide
G - produce gastrin
pancreatic duct pathway
centroacinar > intercalated > interlobular > interlobular > main
intercalated pancreatic ducts
located between secretory portion and intralobular ducts
low cuboidal to squamous
secrete bicarb and water
intralobular pancreatic ducts
cuboidal, lacks striated
secrete bicarb and water
interlobular pancreatic ducts
low columnar
secrete bicarb and water
main pancreatic duct
joins bile duct
enters duodenum
lined by tall columnar cells
what is the portal triad
hepatic portal vein
hepatic artery
bile duct
what is the structural organization of the liver?
CT stroma (neurovascular structures travel in here)
parenchyma
sinusoidal capillaries
spaces of disse
what is parenchyma?
organized cords of hepatocytes stacked like plates and arranged radially around a central vein
what are sinusoidal capillaries
vascular channels between plates of hepatocytes
where are spaces of Disse located?
between the sinusoidal endothelium and hepatocytes
what is the liver capsule
thin dense fibrous CT
arranged collagen (supports) and elastic fibers
where does the liver capsule become thick? why?
at the hilum, supports neuromuscular structures as they course through liver
what covers the capsule where it faces the peritoneal cavity?
serous mesothelium
what is the stroma? what is present here?
continuation of the capsule through the porta hepatis
collagen I, III, and IV to support neuromuscular structures
what are the three functional models of the liver?
classic lobule, portal lobule, liver acinus
classic lobule model
hexagonal shape
central vein is axis with hepatocyte plates radiating from center
blood flow from periphery to center
bile from center to periphery
portal lobule model
trianguler/wedge shaped
portal area is central axis
peripheral landmark is 3 or more central veins
bile flows from periphery to portal area
blood flows from portal area to central vein
liver acinus model
oval to diamond shaped
distributing vein is axis
short axis - 2 terminal branches of portal triad
long axis - line btw two central veins closest to short axis
blood flows from center to periphery
liver acinus zones
zone 1 - closest to short axis and blood supply
zone 2 - between 1 & 3, no defined boundaries
zone 3 - farthest from short axis, closest to central vein
what is the blood supply to the liver?
venous supply via portal vein and arterial supply via hepatic artery
portal vein system
portal vein > distributing vein > inlet venal > sinusoids > central vein > sub lobular vein > hepatic vein > IVC
arterial system
hepatic artery > inlet arteries > sinusoids > central vein
what are hepatocytes?
basic structural component of the liver
grouped in interconnected plates
capable of considerable regeneration
hepatocyte structure
generally acidophilic cytoplasm, large, polygonal cells, large central nucleus, can be binucleate
two or more nucleoli
what is liver parenchyma?
comprised of anastomosing network of interconnecting hepatocyte plates
can be 1-2 cells thick
what are bile canaliculus
formed by two hepatocyte cell membranes
where are hepatic sinusoids located? what are they lined by?
between hepatocytes
lined by endothelial cells - fenestrated, discontinuous basal lamina, dark ovoid nuclei projecting into lumen
what is a unique feature of hepatic sinusoids?
presence of stellate sinusoidal macrophages, Kupffer cells, in the lining of vessels
Kupffer cell origin and structure
derived from monocytes
interposed with fenestrated endothelial cells, form integral part of sinusoid walls
irregular in shape
filopodia and microvilli on luminal side
lysosomes and endocytotic vesicles
vermiform processes
what do Kupffer cells play a role in?
host defense and breakdown of RBCs
what is the space of Disse?
perisinusoidal space
exchange site between blood and liver cells
where is the space of Disse located?
between basal surfaces of hepatocytes and endothelial cells
what is located within the space of Disse?
hepatocyte microvilli
Ito cells (stellate cells)
what are Ito cells
fat containing cells - retinyl esters
lipid droplets, small nucleus, many long branched cytoplasmic processes
store exogenous vit A retinol
what is bile production?
an exocrine function of liver hepatocytes
what does bile contain?
conjugated and degraded waste products
substances that bind to metabolites to aid in absorption
what are cholangiocytes?
epithelial cells that line the biliary tree
organelle-scant cytoplasm
tight junctions
complete basal lamina
microvilli
primary cilium
what are bile canaliculi?
small canal formed by apposed grooves in the surface of adjacent hepatocytes
smallest branches of the biliary tree
aka short canals of Hering
canal of Hering
lined by hepatocytes and cholagiocytes
contractile activity
duct pathway
canal of Hering > tntrahepatic bile ductule > interlobular ducts > join to form R/L hepatic ducts > common hepatic ducts
what parts of the biliary ducts are lined by cholangiocytes?
canal of Hering and interlobular ducts
what are the extra hepatic bile ducts?
common hepatic duct
cystic duct
common bile ducts
common hepatic duct
tall columnar epithelium
alimentary canal layers except muscularis mucosae
cystic duct
carries bile in/out of gallbladder
spiral valve (spirally arranged mucosal folds)
simple columnar epithelium
thin lamina propria
smooth muscle
muscularis externa
serosa
common bile duct
extends to wall of duodenum at hepatopancreatic ampulla
sphincter of common bile duct and hepatopancreatic ampulla
major duodenal papilla
what is the gallbladder?
pear-shaped distensible sac
receives dilute bile from cystic duct via hepatic duct
store and removes water from incoming bile
releases bile into common bile duct
gallbladder mucosa
simple columnar epithelium
tall epithelial cells with microvilli
primary cilium
apical junctional complexes
mitochondria
lateral plications
gallbladder lamina propria
fenestrated capillaries and small venules
no lymphatics
contains large amount of lymphocytes and plasma cells
scattered smooth muscle
mucous glands
other gallbladder layers
muscularis externa - collagen and elastic fibers, stimulated by CCK
adventitia - dense CT, elastic and adipose
serosa - unattached surface, mesothelium, loose CT
