Term
| liver gross histological organization |
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Definition
| surrounded by delicate connective tissue capsule (Glisson's capsule) and divided into four lobes; CT entering liver at the porta branches within the liver to produce many septa which delineate the lobules; portal vein and hepatic artery enter liver at the porta and branch extensively to supply lobules with blood and bile ducts exit the liver at the porta; lobules drained by hepatic veins which pass through parenchyma of liver to empty into the IVC |
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Term
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Definition
| hexagonal in shape and its edges are outlined by connective tissue; has at the corners areas of connective tissue that contain branches of hepatic artery, portal vein, and bile duct-called portal triads |
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Term
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Definition
| drains blood at center of lobule into hepatic veins via sublobular veins |
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Term
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Definition
| hepatic cells radiating from central vein typically one to two cells thick and may anastomose with each other |
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Term
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Definition
| blood passageways on either side of a plate link branches of portal vein and hepatic artery to central vein |
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Term
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Definition
| emphasizes exocrine function of the liver-no definitive boundries and defined by edges connecting the three central veins of three adjacent classical lobules and at center is a bile duct or portal canal and bile drains toward the bile duct |
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Term
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Definition
| emphasizes blood flow to the hepatocytes formed by portions of two adjacent lobules; outer edges defined by drawing line from central vein of one lobule to a portal canal and to a central vein of adjacent lobule and back; center of this lobule is CR lying between adjacent lobules which houses branches of portal vein and hepatic artery |
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Term
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Definition
| blood flows from center of hepatic acinus to central vein and zone 1 has most oxygen and most nutrients and zone 3 has least oxygen and least nutrients |
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Term
| characteristics of sinusoids |
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Definition
| larger than capillaries and has lining that presents a minimal barrier to substance reaching the hepatocyte surface; there are gaps between adjacent endothelial cells and basal lamina is discontinuous and endothelial cells bear fenestrate |
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Term
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Definition
| phagocytic cells in sinusoids lie on the surfaces of endothelial cells and send cytoplasmic processes between endothelial cells |
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Term
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Definition
| sinusoidal epithelium is seperated from underlying hepatocytes by a narrow space constaining blood plasma, microvilli of hepatocytes, fine reticular fibers, and fat storing cells (storage of vitamin A) |
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Term
| blood supply to the liver |
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Definition
| portal vein (75% of blood) and hepatic artery (25%) enter porta and go into sinusoids which go into central vein to sublobular vein to hepatic veins to inferior vena cava |
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Term
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Definition
| tiny channel which lies at the interface between adjacent liver cells, its walls are formed by the plasma membrane of apposed hepatocytes; drains bile towards bile ducts located at periphery of lobule; lumen is expansion of intercellular space and sealed off from remaining intercellular space by tight junctions and form 3-D anastomosing net around hepatocytes |
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Term
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Definition
| bile canaliculi drain into and line by simple epithelium ranges from low cubodial to columnar |
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Term
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Definition
| secreted about 500-1000ml per day; contains water and electrolytes along with certain lipids (bilirubin and bile acids) |
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Term
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Definition
| large polyhedral have microvilli on surfaces and contain one or more rounded nuclei contain lysosomes, peroxisomes, mitochondria, glycogen, lipiddroplets, abundant RER and SER, golgi complex, etc |
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Term
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Definition
| processing and storage of major foodstuffs also removes water from the blood, produces bile, synthessizes several major proteins (albumin, globulins and clotting factors fibrinogen and prothrombin) and role in drug detoxification and hormone nactivation |
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Term
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Definition
| forms by the fusion of cystic duct and common hepatic duct and latter joins with the pancreatic duct to empty into the duodenum |
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Term
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Definition
| has a mucous membrane thrown into folds that flattern out as gall bladder becomes distended; epithelium is simple columnar with cells that are tall and have microvillar surface have basal nuclei and lateral interdigitations; and lamina propria is loose CT and no submucosa is present; composed of circularly arranged smooth muscle and well developed perimuscular CT layer and has a serosa |
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Term
| functions of the gall bladder |
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Definition
| functions as temporary storehouse for bile and concentrates the bile via a sodium dependent resorption process by epithelial cells |
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Term
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Definition
| hormone that brings about the release of bile causes smooth muscle of the gall bladder to contract and expell bile into common bile duct and into the duodenum |
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Term
| secretory end pieces of pancreas |
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Definition
| made up of serous ascini containing acinar cells and centroacinar cells; role is to produce and store digestive enzymes; majority of enzymes are in inactive form until reach duodenum |
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Term
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Definition
| main pancreatic duct lined by tall simple columnar epithelium gives rise to interlobular and intralobular ducts; intralobular are called intercalated ducts very small in diameter and lined by very low simple cubodial epithelium |
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Term
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Definition
| intercalated cells that are trapped within ascini |
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Term
| functions of exocrine pancreas |
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Definition
| secretes about 1-2 liters per day contain high concentration of NaHCO3 making it highly alkaline and variety of digestive enzymes; normally releases stored secretions when acidic chyme enters the duodenum |
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Term
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Definition
| produced by enteroendocrine cells in the intestinal mucosa bringing about release of bicarbonate rich watery secretion from intercalated duct cells |
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Term
| after pancreas secretions enter duodenum |
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Definition
| trpysinogen is converted to trypsin and converts remaining proenzymes to their active forms and bicarbonate solubilizes the digestive enzymes which where released in concentrated form and helps to produce neutral pH need for pancreastic enzymes to carry out the break down of food |
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Term
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Definition
| small clusters of cells scattered throughout the exocrine pancreas comprise the endocrine portion of pancreas; arranged in compact mass and these are richly vascularized and contain fenestrated capillaries and no ducts |
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Term
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Definition
| most numerous secrete insulin promoting uptake of glucose and reduces reduction of rate of breakdown of glycogen in liver |
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Term
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Definition
| less numerous and secrete glucagon act antagonistically to insulin and leads to inrease in amount of blood sugar |
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Term
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Definition
| secrete somatostatin and local effect is to suppress release of insulin and glucagons |
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Term
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Definition
| PP cells contain pancreatic polypeptide which may be involved in local regulation of acinar cell secretion; islet cells also secrete gastrin |
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Term
| cephalic phase control of pancreatic secretion |
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Definition
| results from central integration of visual, olfactory, and tactile stimuli stimuli associated with meal and excitatory vagal efferent fibers from DMX activate ganglion cells within the acinar and ductile cell areas of the pancreas and produce a low volume secretion with high protein content |
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Term
| gastric phase of pancreatic control |
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Definition
| initiated by distension-mediated vagovagal reflex and by amino acid and peptide induced release of gastrin from antral G cells and response is slight to moderate increase in enzyme secretion |
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Term
| intestinal phase pancreatic control |
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Definition
| delivery of chyme into upper small intestine major stimulus mediated by cholinergic reflexes and release of hormones; enteropancreatic reflex most likely due to CCK stimulation of afferent vagal neuron which leas to a vago-vagal reflex |
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Term
| feedback inhibitory factors modifying release from pancreas |
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Definition
| bile salts and trypsin decrease CCK release and pancreatic polypeptide released upon vagal stimulation; and peptide YY released from distal small bowel and colon |
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Term
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Definition
| bile acids, lecithin, cholesterol, bilirubin, protein, Na, K, Ca, Cl, HCO3 |
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Term
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Definition
| involves conversion of cholesterol into primary bile acids, cholic and chenodeoxcholic acid and rate limiting step is catalyzed by 7a-hydroxylase represents 50% of daily turnover of cholesterol; secondary bile acids are formed from action of bacterial enzymes on primary bile acids; and bile acids are conjugated with glycine or taurine resulting in inonization of bile salt increasing water solubility |
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Term
| bile-acid independent flow (BAIF) |
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Definition
| reflects water and electrolyte secretion by hepatocytes and ductile cells; about 1/3 of total bile flow; formation of alkaline watery bile devoid of bile acids is referred to as hydrocholeretic effect can be increased by secretin |
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Term
| bile acid dependent flow (BADF) |
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Definition
| driven by the canalicular secretion of bile acids carrier mediated process results in passive paracellular and transcellur movement of water and electrolytes due to osmotic effect of secreted bile acids; choleretic effect; depends on integrity and efficiency of enterohepatic circulation |
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Term
| reabsorption of bile salts |
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Definition
| because most bile salts are large, ionized molecules do not pass readily through lipid membrane; remain in high concentration in proximal bowel where they facilitate fat digestion and absorption and special active transport processes are localized to the terminal ileum; some passive absorption of bile salts occurs along entire length of small bowel and in the colon (deconjugated bile salts and some glycine conjugates) |
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Term
| storage and concentration of bile in gall bladder |
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Definition
| in interdigestive period hepatic bile enters the gallbladder and volume is 50mL and must reabsorb most of volume presented to it and occurs via active absorption of NaCl and NaHCO3 |
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Term
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Definition
| major stimulus is presence of fat and protein digestion products in the upper small intestine products in the upper small intestine; release CCK from endocrine cells, promoting smooth muscle contraction and sphincter of Oddi smooth muscle relaxation; partial empyting can be demonstrated during cephalic and gastric stages of digestion |
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