Liver, Gallbladder, Pancreas, Spleen Flashcards
describe the liver and its functions
LARGEST GLAND
functions:
-carb, protein, fat metabolism
-forms bile
-destroys old red blood cells
-vitamin and iron storage
what does bile do?
mixes with chyme in stomach
needed for emulsification, absorption and digestion of fat and makes intestinal contents more alkaline
what is contained within the lesser omentum?
portal structures
what is the hepatic artery?
+ branches supply oxygenated blood to the liver = roughly 25% of liver’s blood supply
what is the portal vein?
delivers blood drained from abdominal digestive organs to the liver
delivers roughly 75% of liver’s blood supply
what is the bile duct?
delivers bile from liver (and gall bladder) to the duodenum
what does the portal (=hepatic portal) vein collect blood from?
1) gastroduodenal vein
—> craniopancreatico-duodenal vein (L lobe of pancreas and duodenum)
—> right gastroepiploic vein (greater curvature of stomach)
2) splenic vein
—> left gastroepiploic vein (greater curvature of stomach)
—> pancreatics (R lobe of pancreas)
name the 3 parts of the portal triad (flow of blood and bile within lobular liver)
1) portal areas (traids, tracts, fields)
2) hepatic sinusoids, bile canaliculi
3) centrilobular region
describe the portal areas of the portal triad
regions containing microscopic branches of the portal vein, hepatic artery and bile ductule
bile ductule lined by cuboidal cholangiocytes
describe the hepatic sinusoids/bile canaliculi of the portal triad
hepatocytes interact with venous and arterial blood in hepatic sinusoids
also secrete bile into bile canaliculi that transport bile to the bile ductules as part of the biliary system
canaliculi = channels formed by tight junctions between hepatocytes
describe the centrilobular region of the portal triad
deoxygenated, processed blood is carried to the central vein which ultimately drains into the caudal vena cava
how does the liver drain to caudal vena cava?
via hepatic veins
multiple hepatic veins drain blood from the liver –> anatomically very short
describe the functions of the gall bladder
-bile storage (from liver)
-concentration –> removal of water from electrolytes
-duodenum/jejunum release cholecystokinin that causes gallbladder to rhythmically contract and causes sphincter of the hepatopancreatic ampulla to relax in order to release bile into duodenum
-bile emulsifies fat
what does the sphincter of oddi do?
controls bile and pancreatic juice drainage
-prevents bile from entering duodenum and instead it flow up the cystic duct to gallbladder for concentration and storage
describe the mucosa in the gallbladder
simple columnar epithelium with short microvilli
Na+ and water are transported into the lamina propria as part of bile concentration
describe the muscularis externa in the gallbladder
multiple smooth muscle layers for peristalsis to empty bile from gallbladder
describe adventitia/serosa in the gallbladder
dense CT adventitia anchors it to the liver –> free surface covered by serosa (peritoneum)
how does bile flow in the equine liver
FLOWS CONTINUALLY BC NO GALLBLADDER
widened bile duct delivers bile to duodenum
describe the pancreatic ducts and the pancreas type
pancreatic ducts form within the body of the pancreas and drains into the duodenum
–> smaller gland with 2 components: exocrine and endocrine
describe the exocrine gland component of the pancreas
produces a digestive juice that is discharged into duodenum through ducts
juice contains enzymes that break down protein, carbs, and fats
describe the endocrine gland component of the pancreas
cell clumps scattered between exocrine acini called pancreatic islets –> are the source of insulin, glucagon, and gastrin
critical for carb metabolism
what is the left lobe of the pancreas adjacent to? the right lobe?
left: adjacent to great curvature
right: descending duodenum
how do the exocrine secretions work in the pancreas?
secrete digestive enzymes from pancreatic acini
acinus –> intercalated duct –> intralobular duct
how do the endocrine secretions work in the pancreas?
secrete hormones from islets of langerhans
release into capillaries
what are acinar cells?
release granules of digestive enzymes
what are centroacinar cells?
produce alkaline fluid to keep digestive enzymes inactive
describe pancreatic acini
compound tubuloacinar serous glands
40-50 acinar cells per pancreatic acinus
basal lamina separates acinar cells from septa
3-4 centroacinar cells of intercalated duct in lumen
what is the function of islet of langerhans?
secrete hormones that regulate blood sugar and digestion into fenestrated capillaries
describe islet of langerhans
1 islet may contain hundreds of cells
1 million islets per pancreas
pale staining cells
each islet is heavily vascularized
describe alpha/A cells
20% of islet cells
periphery of islet
PRODUCES GLUCAGON
describe beta/B cells
70% of islet cells
center of islet
PRODUCES INSULIN
describe delta/D cells
5% of islet cells
periphery of islet
PRODUCES SOMATOSTATIN
what 2 arteries anastomose along the pancreas and 1st part of duodenum
celiac and cranial mesenteric arteries
describe the spleen and its functions
LARGEST LYMPHOID ORGAN
functions:
-store RBC’s and platelets
-destroy old RBC’s
-filters foreign particles, bacteria and phagocytic cells
-produce lymphocytes
where does the spleen originate?
dorsal mesogastrium
describe the red pulp of the spleen
contains numerous macrophages in splenic cords and splenic sinuses that hemolyze damaged RBCs
describe the white pulp of the spleen
contains about a quarter of the body’s lymphocytes that attack antigens circulating in blood
