Lecture 32: Abdomen V Liver, Gallbladder, Pancreas, Spleen Flashcards
what is the largest gland in the body
liver
liver functions (4)
-carbohydrate, fat and protein metabolism
-forms BILE
-destroys old RBCs
-vitamin and iron storage
destruction of RBCs in liver (what happens)
hemoglobin is excreted as bilirubin in bile
contents of bile (6)
-detoxified waste
-bile salts
-cholesterol
-phospholipid
-bilirubin
-electrolytes
why is bile necessary (4 functions)
-emulsification
-absorption
-digestion of fat
-make intestinal contents more alkaline (raise pH)
what cells produce bile
hepatocytes
what does bile mix with for absorption
chyme
location of liver
cranial to stomach
2 surfaces of liver
-visceral
-diaphragmatic
visceral surface of liver
impressions made by stomach
diaphragmatic surface
pull diaphragm away
6 lobes of liver
-right and left lateral
-right and left medial
-quadrate
-caudate
blood supply to liver
-majority from portal vein
-some from hepatic artery
hepatoduodenal ligament
portion of lesser omentum containing portal structures (hepatic artery, portal vein, bile duct)
hepatic artery
supply oxygenated blood to liver (25%)
portal vein: definition
delivers blood drained from abdominal digestive organs to liver
delivers 75% of liver’s blood supply
bile duct
delivers bile from liver and gallbladder to duodenum
where does portal vein receive blood from (2 with branches)
-gastroduodenal vein (right gastroepiploic, cranial pancreaticoduodenal)
-splenic vein (left gastroepiploic, pancreatics)
portal triad: 3 components
-portal areas
-hepatic sinusoids, bile canaliculi
-centrilobular region
portal areas: portal triad
-contain branches of portal vein, hepatic artery and bile duct
hepatic sinusoids: portal triad
-hepatocytes interact with venous and arterial blood
-hepatocytes secrete bile into bile canaliculi
bile canaliculi: definition and function
-channels formed by tight junctions between hepatocytes
-transport bile to bile ductules (biliary system)
centrilobular region: portal triad
-deO2 blood carried to central vein
where does central vein drain to
hepatic vein –> caudal vena cava
which direction does bile travel vs blood
opposite
bilirubin: definition
brown pigment from breakdown of heme
-excreted in bile
how blood and bile flows within portal triad
-material in sinusoidal blood passes through gaps in endothelial cells to enter perisinusoidal space of Disse –> absorbed by hepatocytes
gallbladder functions (3)
-collect and store bile from liver
-concentration of bile (remove water and electrolytes)
-release bile into duodenum
what is gallbladder surrounded by
lobes of liver
how does gallbladder release bile into duodenum
-duodenum and jejunum release cholecystokinin to cause rhythmic contraction of gallbladder and relaxation of sphincter of hepatopancreatic ampulla
biliary tree
-Hepatic ducts drain into main cystic duct that drains to bile duct which drains into duodenum
-bile duct joins pancreatic duct
what structure controls bile and pancreatic juice drainage
sphincter of oddi
contraction of sphincter of oddi (sphincter of bile duct): effects
-prevent bile from entering duodenum
-bile flows up cystic duct to gallbladder for concentration and storage
gallbladder: microanatomy (5 layers and functions)
-muscoa: simple columnar epithelium, short microvilli
-lamina propria: Na+ and water transported to concentrate bile
-muscularis exxterna: smooth muscle layers for peristalsis to empty bile from gallbladder
-adventitia: anchors to liver
-serosa: peritoneum, covers free surface
what structure/organ do horses lack
gallbladder
equine adaptation to no gallbladder
-widened bile duct = bile delivered to duodenum
-bile flows constantly
what is the largest lymphoid organ in the body
spleen
where do pancreatic ducts form and drain to
-form within body of pancreas
-drains into duodenum
2 gland components of pancreas
-endocrine
-exocrine
pancreas: exocrine gland
-produce digestive juices that are discharged into duodenum through ducts (from pancreatic acini)
-juice contains enzymes that break down protein, carbohydrates and fats
pancreas: endocrine gland
-pancreatic islets (islets of langerhans) source of insulin, glucagon and gastrin for carbohydrate metabolism
left lobe of pancreas adjacent to
greater curvature of stomach
right lobe of pancreas adjacent to
descending duodenum
exocrine secretion of digestive enzymes: process
acinus –> intercalated duct –> intralobular duct
islets of langerhans release hormones into
fenestrated capillaries
2 types of pancreatic acini
-acinar cell
-centroacinar cell
pancreatic acinar cell: definition and function
compound tubuloacinar serous glands
release granules of digestive enzymes
centroacinar cell: definition and function
compound tubuloacinar serous glands
produce alkaline fluid to keep digestive enzymes inactive
which acinar cell contains receptors for cholecystokinin from duodenum
pancreatic acinar cell
3 types of islet cells
alpha
beta
delta
majority of islet cells are what type
beta
alpha islet cells
produce glucagon
beta islet cells
produce insulin
delta islet cells
produce somatostatin
how are islets of langerhans stained
pale
blood supply to pancreas: anastamoses
cranial and caudal pancreaticoduodenal arteries
-pancreaticoduodenal arcade
cranial pancreaticoduodenal artery: parent artery
gastroduodenal –> hepatic –> CELIAC
caudal pancreaticoduodenal artery: parent artery
Cranial mesenteric
spleen: functions (4)
blood reservoir (store rbcs and platelets)
destroy old rbcs
filter foreign particles, bacteria, phagocytic cells
produce lymphocytes
which surface of spleen contacts the kidney
renal surface
which surface of spleen contacts intestines
intestinal surface
which surface of spleen sits next to stomach
gastric surface
greater omentum in spleen aka
gastrosplenic ligament
where does spleen originate/develop from
dorsal mesogastrium
blood supply: spleen (2)
left gastroepiploic artery and vein from splenic artery and vein
short gastric arteries and veins
arterial supply to stomach comes from
splenic artery
why is spleen located adjacent to left region of greater curvature of stomach
stomach rotates during development
feline splenic vasculature: difference
Left gastroepiploics branch from caudal splenic artery and vein (have 2 splenic arteries)
microanatomy of spleen (2 components)
red pulp
white pulp
red pulp: spleen
-contains macrophages that hemolyze damaged rbcs
contains all formed elements of circulating blood
white pulp: spleen
1/4 of body’s lymphocytes that attack antigens circulating in blood
which pulp type constitutes 75% of spleen volume
red
