University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2024
Views:

245

Pages:

107
Author:

Lily Callahan

Liver, Gallbladder, Pancreas, And Salivary Glands Objectives To understand the general organization of the accessory organs of the digestive system and how they contribute to obtaining metabolites necessary for growth and energy for the body. To learn the origin of these glands and how structural features of these glands contribute to their function in digestion and absorption of food stuffs Function of the Digestive System Role of liver, gallbladder, salivary glands, and pancreas Movement of food Salivary glands lubricates Secretion of digestive juices Salivary glands and pancreas secretes digestive juices and liver secretes bile Absorption of digested foods, water, and electrolytes Liver stores nutrients and cleans the blood. Also, the accessory digestive organs contribute antibodies and antibacterial/viral growth substances. Origin And Distribution Of Epithelium Ectoderm - epidermis of skin and epithelium of cornea together covers the entire surface of the body; sebaceous and mammary glands, oral cavity Ectoderm Endoderm - alimentary tract, Liver, pancreas, gastric glands, intestinal glands, gallbladder – Endocrine glands - lose connection with surface Mesoderm Mesoderm Endothelium - lining of blood vessels Mesothelium - lining serous cavities Endoderm ORIGIN AND DISTRIB UTION OF EPITHELI UM con’d Salivary gland 19758 Liver Histo 67 155 Gallbladder Pancreas 158 454 Histo 067 pig liver Human liver Classical liver lobules Separated and surrounded with connective tissue in the pig Mesothelium Connective tissue capsule Monkey liver 118 Liver The hepatocyte functions as an endocrine-like cell (e.g., secretion of glucose and plasma proteins directly into the blood vascular system) and as an exocrine cell (e.g., secretion of bile into the bile canaliculi). This dual export of secretory products by a single cell requires a unique cellular arrangement in the liver in order to separate and compartmentalize the exocrine and endocrine-like products. Hepatocytes are arranged in fenestrated, anastomosing plates of one cell thick. Also each hepatocyte may have as many as four areas of access to the lumen. Landscape of the Hepatocyte – Four Luminal Regions HEPATOCYTE LIVER FUNCTION - LARGEST GLAND EXOCRINE - BILE ACIDS, BILIRUBIN ENDOCRINE ALBUMIN, FIBRINOGEN, ETC. LIVER FUNCTIONS Blood filtration - 1.2 x 107 Kupffer cells/g Blood storage - liver size and sinusoids expand Maintain normal blood glucose concentrations Metabolism and transport of lipids Secrete plasma proteins - blood clotting Nutritional metabolism and bile secretion Drug metabolism - drug tolerance Excretion of bilirubin - jaundice Secrete bile - emulsifying fats Bile from canaliculi Blood from intestine Oxygenated blood from arterial source Portal radicles containing: A bile duct Branch of portal vein, Branch of hepatic artery Lymphatic vessel (usually) or portal canals 155 Liver 155 Cords of hepatocytes 454 Liver Portal radicles containing: A bile duct Branch of hepatic artery Branch of portal vein Lymphatic vessel (usually) 454 Central vein Cords of hepatocytes Bile Canaliculi Bile luminal surfaces 155 Bile duct Blood luminal surface Liver Cells of the Liver Lobule A. Hepatocyte B. Kupffer and fat-storing cells C. Endothelial cell Hepatocyte Kupffer cells Endothelial cell Cells of the Liver Lobule A. Hepatocyte B. Kupffer cells C. Endothelial cell Triad with bile duct, blood sinusoids, and central vein Liver with colloidal carbon, rat 118 Liver Liver Lobule Portal triad Blood supply Central vein Hepatic sinusoids Zonation of the liver Acinus with portal vein and artery in center Zonation of The Liver 1. Classical lobule 2. Portal lobule with triad in center 3. Acinus layers between two central veins Zonation of the liver Classical lobule Classical lobule Portal Lobule with Triad in its Center as the blood travels to each of three central veins Acinus with portal vein and artery (between two triads) in its center as the blood travels through three zones on its way to each of two central veins. Acinus with portal vein and artery in center Acinus If liver damage is due to a toxicant, it kills hepatocytes in Zone I first. If liver damage is due to a oxygen deprivation, it will kill the hepatocytes in Zone III first. Hepatocyte organelles HEPATOCYTE Hepatocyte organelles Histological Reaction for Peroxidase Hepatocyte Hepatocyte Space of Disse Bile canaliculi Space of Disse = serum bath hepatocytes’ microvilli Hepatic sinusoid Hepatic parenchymal cells with microvilli Endothelial cell projecting into sinusoid Bile canaliculi with lysosomes close by the canaliculi Liver cells EM 18 Platelet Space of Disse containing reticular fibers Sugar and protein Glycogen (red granular clumps) in Hepatocytes Dietary Differences In Amount Of Glycogen In Hepatocytes 2-hour Fast (8.2% Glycogen) 24-hour Fast (0.9% Glycogen) Disease opportunity at each step in a pathway SER Surface Specializations of Epithelia Transcytosis is used to get antibodies into secretions “Transcytosis is a type of transcellular transport in which various macromolecules are transported across the interior of a cell.” Four + compounds that are deposited/secreted into the bile canaliculus. a. Cholesterol b. EGF c. insulin d. IgA Bile canaliculi also bile salts and BILIRUBIN Bilirubin is the brownish-yellow substance of bile. It is produced when phagocytic cells of the liver, spleen, or bone marrow breaks down old red blood cells. Bilirubin removed from the body in liver bile through the stool (feces). Bilirubin gives stool its normal color. Bilirubin circulates in the bloodstream and too much can cause jaundice (yellow skin). Bile Canaliculi Bile Duct Gallbladder & Bile Ducts Function Biliary tract Organization of gallbladder Epithelium Connective tissue Histophysiology Gallbladder The mucosa is thrown into folds which project into the lumen of the gallbladder. 155 Smooth muscle layer or branching layers Lamina propria. A thick perimuscular layer of connective tissue. Simple columnar epithelium Peritoneal serosal layer The gallbladder stores and concentrates the 155 Mucosa bile elaborated by the liver Plasma cells In the lamina propria Simple columnar epithelium 126 Bile duct with portal vein, monkey Portal vein Cystic duct Common hepatic duct The wall of the cystic duct is convoluted and contains abundant smooth muscle fibers which represent the spiral valve preventing distention or collapse of the cystic duct when the latter is subject to sudden changes of pressure. Gallstones may form if your body is already producing too much bilirubin due to a liver condition or if your liver's creating too much cholesterol. They can also be a complication of an infection of your bile ducts or from a blood disorder. Bilirubin builds up when your gallbladder's blocked and can't drain properly. Distinguishing characteristics between the mucosa of the various parts of the stomach, intestines, and gallbladder. Mucosa = surface epithelium, lamina propera, and muscularis mucosa Cardiac stomach Fundic stomach 437 145 Pyloric stomach 141 Intestines 148 Gallbladder 155 Salivary Glands Function Histological organization Acinus = functional unit Serous Mucous Mixed Origin of Salivary Glands? • Ectoderm - oral ectoderm epithelial sheet • Endoderm - alimentary tract Saliva Helps Prevents Infections Contains secreted IgA Contains lactoferin - bind up iron needed for bacteria division Contains lysosome that kills bacteria Constantly washes mouth to dislodge and sweep bacteria down GI tract Salivary Glands Salivary Glands Ducts of Salivary Glands Intercalated Striated 19758 Submandibular gland - intercalated duct runs into striated duct of salivary gland The salivary gland is a compound, tubuloacinar gland. 130 Striated Ducts These striations reflect vertically arranged mitochondria associated with deep enfolding of the basal plasma membrane Secretory acini Intercalated ducts 130 Salivary gland Secretory acini are drained by intercalated ducts and join striated ducts Serous and mucous acini Myoepithelial cells Salivary gland Striated ducts drain into a series of interlobular ducts Lobules Adipose cells Serous and mucous acini Demilune 130 Artery Vein Individual secretory acini are drained by intercalated ducts and join striated ducts Interlobular ducts Myoepithelial cells Salivary glands 440 Lobules 440 Histo 52 Nerve cell bodies Striated ducts Serous and mucous acini Nerve 19758 PANCREAS FUNCTION 1. EXOCRINE 2. ENDOCRINE HISTOLOGICAL ORGANIZATION, EXOCRINE PORTION 1. ACINI 2. DUCTS ENDOCRINE PORTION • ISLETS OF LANGERHANS HISTOPHYSIOLOGY 36723 Beginning of intercalated ducts Intercalated duct Islets of Langerhans Interlobular duct 156 and 157 Pancreas 157 156 36723 Intercalated duct 36723 Secretory granules All acini are of the serous type and many contain centroacinar cells initiate the duct inside the acinus. 157 Langerhans 158 Pancreas - IsletsTheofpancreas is a compound Intercalated duct Insulin is secreted by the B cells which are most numerous and centrally located in the islets. tubuloalveolar (tubuloacinar) gland which functions in the digestion of food. Lobes composed Islets of Langerhans of lobules Connective tissue septa. Blood vessels Nerve Interlobular duct EM 1 Pancreatic acinar cell (EM 1) 1. Lumen 2. Zymogen granule 3. Vesicles 4. Central acinar cell In summary 148 Ileum Meissner’s plexus cell bodies in submucosa Paneth cells Submucosa Small intestinal villi Slide 66: Recto-anal junction Internal anal sphincter Anus Rectum Questions on the Liver, pancreas, and salivary glands The humoral activity of the immune system is illustrated by the transfer of IgA immunoglobin by epithelial cells into which of the following body fluids? a. saliva b. milk c. bile d. a and b e. a, b, and c Which function(s) do the gallbladder and urinary bladder have in common? a. temporary storage of waste products b. concentration of their respective luminal contents c. similar type of luminal epithelium d. a and b e. a, b, and c Characteristics of the pancreas include: a. a portal blood vascular system b. endocrine cells of the islets of Langerhans c. acinar cells and striated ducts d. a and b e. a, b, and c

Liver, Gallbladder, Pancreas, and Salivary Glands

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