Accessory Organs of the Digestive Tract Flashcards
Pancreas is what type of gland
Exocrine
Liver is what type of gland
Endocrine and exocrine gland
Myoepithelial cells
Located b/w epithelial cells and basal lamina
Assist in moving secretory products towards the excretory duct
Pathway of saliva flow
Acinus Intercalated duct (low cuboidal) Striated duct (simple cuboidal to columnar) Excretory duct (simple cuboidal to pseudostratified columnar or stratified cuboidal)
Parotid glands
Largest salivary gland, may have adipocytes near
Acini consist of only serous secretory cells
Pyramidal cells with basal nucleus and prominent RER
Secretory granules visible in apical region
Sublingual glands
Branched tubule-alveolar gland with both serous and mucous cells
Predominantly mucous cells
Intercalated and striated ducts are poorly developed
Submandibular gland
Serous cells are predominant, but also has mucous cells
Mucous cell containing acini are capped by serous demilunes
Myoepithelial cells control serous secretions
Intercalated ducts are shorter and striated ducts are longer than those in parotid gland
Exocrine vs endocrine pancreas function
Exocrine- synthesizes/secretes enzymes that are essential for digestion in intestine
Endocrine component- synthesizes/secretes hormones (insulin and glucagon) into the blood
Exocrine pancreas
Serous acini
Contains pancreatic acinar cells
Intercalated duct begins w/in the acinus
Centroacinar cells, duct cells inside the acinus
^^ they are continuous with low cuboidal epithelium of intercalated duct
Pancreas often confused with parotid glands
Acinar vs centroacinar cell staining
Acinar cells stain intensely, centroacinar cells stain lightly
Pancreated acinar cell
Well developed ER
Prominent Golgi
Apical domain of zymogen granules that contain tons of proenzymes such as trypsinogen, a-amylase, lipases, ribonuclease
Endocrine pancreas
Spherical masses of endocrine cells, surrounded by thin reticular capsule
Islets arise from endodermal epithelial outgrowths
a-cells vs b-cells vs d-cells vs PP cells
a - secrete glucagon
b- secret insulin
d- secrete somatostatin (least abundant)
PP- secrete pancreatic polypeptide
Liver
Enclosed in thin CT capsule lined with mesothelium of visceral peritoneum
Hepatocytes function in metabolism, storage, and bile production
Hepatocytes (histo description) and bile
Large polygonal cells with eosinophilic cytoplasm and microvilli
Large spherical nuclei, man are binucleate, most are tetraploid
Hepatocytes secrete bile that drains into bile canaliculus, which is lined with cholangiocytes b/w hepatocytes
Canaliculi join to eventually contribute to biliary tree
Bile function
Fat absorption, excretion of cholesterol, bilirubin, iron and copper
Hepatic lobules
Liver parenchyma is organized as hepatic lobules
Hepatocytes form irregular plates radiating from a central vein
Plates are supported by a stroma of reticular fibers, and separated by sinusoids
Portal triad
Venule branch of the portal vein
Arteriole branch of the hepatic artery
Bile ductules (1-2), branches of the bile conducting system
Hepatic sinusoids
Anastomosing capillaries that perfuse hepatocytes w/portal and arterial blood
Contain Kupffer cells and hepatic stellate cells
Kupffer cells
Stellate macrophages within endothelium of sinusoids
Larger than endothelial cells
Detect and phagocytose defective erythrocytes
Distinguishes hepatic sinusoids
Hepatic stellate cells
Cells with small lipid droplets that store vitamin A and other fat soluble vitamins
Perisinusoidal space (of Disse)
Located b/w hepatocytes and sinusoidal endothelium (discontinuous capillaries)
Creates a potential space for exchange of materials b/w blood and hepatocytes
-microvilli project into this space, which is filled w/plasma
-Increases surface area for exchange of material
Bile canaliculi
Anastomosing network of channels formed by hepatocyte plates
End near portal triads
Bile canaliculi drain into canals of Hering, composed of cuboidal epithelial cells called cholangiocytes
Bile pathway
Bile canaliculi Canals of Hering Bile ductules Merge and enlarge Right/left hepatic ducts
