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36 Cards in this Set
- Front
- Back
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What are the characteristics of the pancreas?
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-Situated retroperitoneal
-Four regions: uncinate process, head, body, tail -25cm long, 5cm wide, and 1-2 cm thick -approximately 150 g -flimsy connective tissue capsule forms septa, which subdivide the gland into lobules -mixed gland: endocrine and exocrine |
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What types of glands are found in the pancreas?
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-Exocrine: secrete digestive enzymes, bicarbonate rich buffer
-Endocrine: hormones |
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What are the characteristics of the exocrine glands of the pancreas?
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-Compound tubuloalveolar gland
-1200 ml/day buffer + digestive proenzymes -Acinus lumen have 3-4 centroacinar cells |
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How do exocrine secretions pass through the pancreas?
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1. Intercalated ducts
2. Intralobular ducts 3. Interlobular ducts 4. Main pancreatic duct 5. Joins the common bile duct 6. Opening in the duodenum at the papilla of Vater |
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What receptors are found on pancreatic acinar cells?
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-cholecystokinin
-acetylcholine |
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What receptors are found on centroacinar cells?
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Secretin
Acetylcholine |
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What is cholecystokinin?
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-Released from I-cells in duodenum and jejunum
-Stimuli for release *Fatty acids or monoglycerides *Peptides and single AA *Acid -Potent stimulator of enzyme secretion -Emptying of gallbladder - contracts gallbladder, relaxes sphincter of Oddi -Inhibits gastric emptying |
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What is secretin?
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-Released from S-cells of duodenal mucosa
-Stimuli for release: *acid in duodenum (pH <4.5) *Fatty acids in duodenum -Physiological effects: NATURES ANTACID *stimulates pancreatic and bile bicarbonate secretion *inhibits gastric acid secretion |
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What does the secretory portion of the exocrine glands of the pancreas secrete?
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-Secrete Digestive Enzymes: pancreatic amylase, pancreatic lipase, ribonuclease, deoxyribonuclease
-Proenzymes: trypsinogen, chymotrypsinogen, procarboxypeptidase, elastase -Trypsin inhibitory Release of enzymes is affected by cholecystokinin and acetylcholine |
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What are the functions of the duct portion of the exocrine glands in the pancreas?
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-Generate serous bicarbonate-rich alkaline fluid
-Neutralizes and buffers the acidic chyme -Release effected by hormone secretin -Enzyme-rich and enzyme poor secretions are regulated separately -May be released at different times or concomitantly |
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What are the islets of Langerhans?
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-endocrine cells scattered among the acini.
-Richly vascularized -3000 cells -1 million islets/pancreas - greater number in the tail |
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What do the delta cells of the islets secrete?
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Somatostatin
Reduces conctractions of alimentary tract and gallbladder smooth muscles |
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What do the G cells of the islets secrete?
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Gastrin
Stimulates production of hydrochloric acid by parietal cells of stomach |
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What are characteristics of the Liver?
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-1500 grams
-Largest gland in the body -Upper right-hand quadrant of abdominal cavity -Four lobes: right, left, quadrate, caudate |
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What are the functions of the liver?
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-Endocrine and exocrine functions
-Hepatocytes responsible for BOTH exocrine (BILE) and endocrine products -Synthesize blood proteins -Maintain blood glucose -Deamination of amino acids -Detoxification of drugs and toxins -Storage of vitamin A and Glycogen -Metabolize chylomicrons -Manufacture bile |
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What is the blood supply of the liver>
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-Hepatic vein --> blood returning to the heart via the inferior vena cava
-Hepatic artery: brings oxygenated blood -Portal Vein: Nutrient rich blood 75% - bringing blood from the intestines |
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Where does blood from the hepatic vein and portal vein mix in the liver?
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Sinusoids
Drains into the sublobular vein |
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What are the characteristics of a liver lobule?
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-Hexagonal arrangement of hepatocytes
-Central vein in middle -Portal triads at periphery |
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What are the 3 concepts of liver lobules?
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1. Classical lobule
2. Portal lobule 3. Hepatic acinus |
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What are the characteristics of the classic lobule?
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- 1st define histologically
- Portal tracts (connective tissue) in pig liver obvious -Blood flows from the periphery to center -Bile enters into bile canaliculi and flows to the periphery of the lobule to the interlobular bile ducts |
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What are the characteristics of the portal lobule?
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-Bile to periphery not like acini of most glands
-All hepatocytes that deliver their bile to a particular interlobular bile duct constitute a lobule -Defined as the triangular region whose center is the portal area and whose periphery is bounded by imaginary straight lines connecting the three surrounding central veins that form the three apices of the triangle |
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What are the characteristics of the liver acinus?
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- aka Acinus of Rappaport
- Based on blood flow from distributing arteriole - Zone 1 richest in oxygen - Zone 3 most oxygen poor |
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What are the characteristics of hepatocytes?
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-Large
-Organelle-rich (abundant): Free ribosomes, RER, Golgi, mitochondria -Proteins for secretion -Maintain blood glucose -Makes bile |
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What is found in bile?
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Water
Bile salts Phospholipids Cholesterol Bile pigments IgA |
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What are the two bile salts?
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Tauricholic acid
Glycocholic acid |
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What are the two stages of bile secretion?
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1. Hepatocytes bile acids, cholesterols, and organic constituents
2. Watery solution of sodium bicarbonate is added to the bile as it flows through the bile ducts. STIMULATED BY SECRETIN |
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Where is bile concentrated?
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In the Gallbladder
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What is the function of bile?
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Emulsification of Fat
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What are the components of the perisinusoidal space?
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-Type III collagen, no basal lamina
-Fat storing cells (ito, stellate cells) -Pit cells (natural killer cells) |
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What is the function of the intrahepatic ductule?
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Bile canaliculus drains into intrahepatic ductule
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What are the functions of the gall bladder?
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Store, concentration, and release bile
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What are the characteristics of the gall bladder?
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-Small, pear-shaped organ on inferior aspect of the liver
-10cm in length and 4cm in cross-section -Stores about 70ml of bile -Resembles a sack with a single opening -Concentrates bile and releases it into the duodenum as required |
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What are the components of the gall bladder?
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-Simple columnar epithelium (clear cells and brush cells)
-Lamina propria -Sm. Muscle layer (oblique) -Adventitia |
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What is the sphincter of oddi?
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When in closed position, bile backs up the common bile duct and the cystic duct to enter the gall bladder
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How does cholecystokinin affect bile release?
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-Gall bladder to contract
-Sphincter of Oddi Muscles to relax -Injects bile into lumen of duodenum |
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How does acetylcholine affect bile release?
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Stimulates contraction of the gallbladder
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