BIO 446L 1st Edition Lecture 28 Outline of Last Lecture I. Digestive System contda. Stomachi. Gastric pitsb. Small intestinei. duodenumOutline of Current Lecture I. Digestive System contd.a. Small intestinei. Absorption of fatsii. Cryptsiii. MALTiv. Blood vessels and nervesb. Large intestinec. Salivary glandsi. Ductsd. Pancreasi. Acinar cellse. Liveri. Hepatic portalii. Hepatic sinusoidThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.f. Gall bladderCurrent LectureDigestive System contd*note: the small intestine notes belonged in the previous lecture but were accidentally left out, so they are included with this lecture’s notes- small intestineo absorption of fats fats entering the duodenum must be emulsified- fat droplets with water soluble lipase- these lipid particles can then diffuse in and reassemble into triglycerides again and packaged by golgi into chylomicrons (fats packaged into soluble protein shell)- transported in lactiles with lymph and circulated to heart to recirculate to rest of bodyo presence of smooth muscle allows microvilli to move closer or farther away depending on digestive needso crypts gastric pits extending into submucosa specialized endocrine cell= paneth cell- innate immunityo lamina propia MALT peyer patch= essentially lymphoid nodules- lymphoid tissue (MALT)- epithelial enterocytes interrupted by M cells that can bind and transport antigens into area with lymphoid tissue- sieve-like leaky structure helper T cells and B lymphocytes and APCs- B lymphocytes—produce IgA, retransported across enterocytes and into lumeno Blood vessels and nerves Usually arteries/veins flow together Superior mesenteric vein—draining intestinal tract of glucose and amino acids Takes detour to liver before going to heart, joins hepatic portal vein, blood to liver, liver processes glucose and amino acids to hepatic vein to inferior vena cava to heart- Large intestineo Begins at illium Secum—appendix attached Ascending colontransverse colon descending colon Sigmoid Rectum—smooth muscle internal sphincter Anus—skeletal muscle external sphinctero Wall is gathered into rounded sections called Haustra Haustra organized by Teniae coli (smooth muscle)o Colonocyte—absorptive cells Have finger-like invaginations Uses Na ions—osmotic gradient to absorb water- Water enters absorptive cellso Large intestine absorbs lots of water- Accessory organso Salivary glands 2 types of secretions- Serous and mucus Serous acinus—secretes water/serum and enzymes, round- Simple cuboidal- Make way to intercalated duct Mucus tubule—secretes mucus—tubular- Make way to intercalated duct Striated ducts—look like striations (infoldings of basal membrane)- Saliva collects- Sodium concentration decreases by the time that saliva is releasedo Pancreas Acinar cells—associated with blood vessels, secrete enzymes, collected in pancreatic duct, enter duodenum Bile duct from liver with bile will join and combine with enzymes secretedby pancreatic duct Pancreatic acini- Food activates parasympathetic in gut- CCK= stimulates enzyme secretion- Secretin= stimulates bicarbonate secretion- Enzymes activate when they enter the duodenumo Protease activates trypsino Trypsin activates other enzymeso Protease inhibitor prevents activation of trypsin until it’s appropriate- Surrounds beginning of intercalated ducto Some duct cells are internal= centroacinar cellso Liver Hepatic portal vein carries nutrient rich, O2 poor blood Liver stores vitamin A, can remove aged blood cells, stores iron Structure formed from cells and sinusoids, organized in hepatic lobules- Portal triad= periphery of lobuleo Branch of bile ducto Venule of hepatic portal veino Arteriole from hepatic artery- Each lobule separated by connective tissue septum- Reticular fiber network maintains hepatic lobules’ structure framework- Each lobule around a central vein, made up of hepatocyteso Hepatocytes= stacked like bricks, sinusoids run through each layer Immense blood supply Has 2 apical layers Perisinusoidal space between hepatocyte and sinusoido Hepatic sinusoid Fenestrations in endothelia of sinusoid Kupffer cells= macrophages of liver, associated withsinusoids- Detox and removes old RBCs Ito cells- Like fibroblasts- Repair and regenerate liver- Sense disease state (like cirrhosis)o Secrete fibrous network Hepatocytes and bile canaliculi- Bile secreted by hepatocytes collected into bile duct that will lead to gall bladdero Then to common bile duct pancreatic duodenumo Gall bladder Bile emulsifies fat so lipase can digest it CCK stimulates bile to contract and release stored bile Bile stores b cirrhosisecomes very concentrated- Water removed- Absorptive cell absorbs