Accessory Organs (Liver, Pancreas, Gallbladder) Flashcards
What does the liver store?
glycogen, vit A, copper, iron
What does the liver produce?
albumins, lipoproteins, glycoprotiens, prothrombin
What does the liver metabolize?
lipid and cabs
What does the liver degrade?
drugs and toxins
What is the liver blood supply?
hepatic artery: well-oxygenated, 25% of entering blood
portal vein: rich in nutrients, wastes, and other materials (75%)
(blood mixes in sinusoids = vascular channels)
What is the direction of blood flow in the liver?
blood from both hepatic artery and portal vein mix in sinusoids and flow toward central vein
What is the direction of bile in the liver?
Bile is produced by hepatocyte and secreted into bile canaliculi between cells –> Flows toward bile duct
Hepatocytes
exocrine and endocrine; polarized, exrcetory separate from secretory
can have >1 nuceli
Fenestrated endothelial cells
line sinusoids. which facilitate exchange between blood and hepatocytes
Kupffer cells
macrophages: pesudo-fixed in sinusoid; produce cytokines that stimulate fibrosis of lipocytes/ito cells/hepatic stellate cells
Lipocytes (Ito cells)
fat storing cells in perisinusoidal space
store vit A
Pathology: produces ECM components –> cirrhosis
What are the lobular zones of the liver?
Zone 1: (perilobular- closest to center of acinus) gets best of the blood; most active - glycogen/bile salt/lipid/cholesterol synthseis
Zone 2:
Zone 3: (centrolobular - nearest to central vein) less O2 and nutrients, first cells to die; most detox occurs here; glycogen converted to glucose - LIPID ACCUMULATION WITH CHF
What does the apical surface of a hepatic cell face?
surface of bile canuliculi
What do the lateral surfaces of a hepatic cell face?
opposite sides of bile duct where hepatocytes join: TJxns, adherens, etc.
What does the basal surface of a hepatic cell face?
all/both facing sinusoids
Bile canaliculi
form complete loop around all 4 sides of hepatocyte
Canals of herin
short, transformations of bile canaliculi near portal triad
contain: hepatocytes and chorlangiocytes
Chorlangiocytes
contain contractile elements which aid unidirectional bile flow toward portal canal (out of bile duct)
Space of Disse
(perisinusoidal space)
space btwn hepatocyes and sinusiods
allows microvilli to project into space to material in blood can pass freely from capillary to perisinusoidal space to hepatocytes
(fenestra in walls too small for RBC passage)
Exocrine Pancreas
synthesizes and secretes bicarb-rich fluid containing variety of digestive enzymes under influence of CCK secreted by DNES cells –> these secretions are transported into the duodenum via ducts
Endocrine Pancreas
synthesizes and secretes hormones: insulin and glucagon
via blood stream
Centroacinar Cells of pancreas
beginning of intercalated ducts
Intercalated ducts of pancreas
~ same size as acinus
light stain
SECRETIN (from duodenum) triggers release of bicarb and water from intercalated ducts –> neutralize acidity of chyme
What are two cells in salivary glands that are not in pancreas?
no striated ducts in pancreas
no myoepithelial cells in pancreas
Interlobular duct of pancreas
lined by low columnar epithelium, surrounded by dense CT
- occasional goblet or DNES cells
- drain directly into main pancreatic duct (duct of Wirsung, herringbone-like)
Islets of Langerhan
endocrine
lots of FENESTRATED CAPILLARIES
NO DUCTS
light cells
Islets of Langerhans: What do alpha cells secrete?
glucagon = antagonist for insulin (15-20% of islet)
Islets of Langerhans: What do beta cells secrete?
insulin = stimulus for uptake of glucose (~70% of islet)
Islets of Langerhans: What do delta cells secrete?
somatostatin (inhibits sensory activities of alpha and beta cells)
Islets of Langerhans: What do PP cells (F cells) cells secrete?
pancreatic polypeptide hormone = inhibits secretion and intestinal motility; stimulates gastric enzyme secretion
What is the epithelium of the gallbladder?
simple columnar with short mircrovilli.
NO goblet cells, no muscularis mucosa/submucosa
mucosa usually has many folds
lamina propria: highly vascularized, loose CT with elastin and collagen
large #s of lymphocytes and plasma cells
thin, irregular muscularis externa and adventitia containing large BVs and lyphatics
How is bile concentrated?
salt and water diffuse into luminal surface of cell
active fluid transport: salt pumpted from cyto and followed by water into intercellular space –> intercellular space becomes distended –> fluid moves from engorged intercellular space across basal lamina and underlying CT and into fenestrated capillaries
What stimulates bile release?
CCK from duodenum –> contraction
Rakintasky-Ashchoff sinuses
mucosa of gallbladder creates deep clefts, can extend through muscularis externa (look like empty circles of simple columnar epithelium
chronic inflammation can lead to gall stones
