12- Accessory Organs of Digestive Tract Flashcards
These have lubricating, protective, digestive, and absorptive functions mediated by their secretory products.
Digestive Glands
What are the 3 main digestive glands?
Major Salivary Glands
Exocrine Pancreas
Liver
These digestive glands are associated with the oral cavity through independent excretory ducts.
Major Salivary Glands
These digestive glands secrete its alkaline aqueous and enzymatic product into the duodenum.
Exocrine Pancreas
This digestive gland is an endocrine and exocrine gland with extensive access to the blood circulation.
Liver
Salivary glands consist of a CT capsule with septa, dividing the gland into lobes and smaller lobules. These provide routes for _________.
Neurovasculature
In Salivary glands, secretory cells organized in an ________ produce saliva via ANS control.
Acinus
Describe the path of excretion via ducts in Salivary glands.
Acinus — Intercalated Duct — Striated Duct — Excretory Duct
This type of acini has cloudier-looking cytoplasm and produces thick, glycoprotein-rich product.
Mucous Acini
This type of acini has clear-staining cytoplasm and produces a water-based product.
Serous Acini
This type of acini contain a core of mucous cells surrounded by a serous demilune.
Mucoserous
_________ cells are located between epithelial cells and basal lamina, and assist in moving secretory products toward the excretory duct.
Myoepithelial
Describe the pathway of saliva flow, and state what type of epithelium is present at each stage.
Acinus —>
Intercalated Duct (Low Cuboidal) —>
Striated Duct (Simple Cuboidal-to-Columnar) —>
Excretory Duct (Simple Cuboidal – Pseudostratified Columnar or Stratified Cuboidal)
What are the types of salivary glands?
Parotid
Submandibular
Sublingual
This type of salivary gland is the largest, and adipocytes may be present. Acini consist mainly of serous secretory cells.
Parotid Gland
The hallmarks of this type of salivary gland are the following:
- Serous only
- Adipose tissue
- CN VII pass through
Parotid Gland
Parotid Glands have _________ cells with a basally located nucleus and prominent RER in the basal region. Secretory granules are visible in the apical region.
Pyramidal
This type of salivary gland is a branched tubule-alveolar gland with both serous and mucous cells. It lacks a defined capsule, but is divided by CT into small lobes. Intercalated and striated ducts are poorly developed.
Sublingual Gland
This type of salivary gland is a mixed gland, but predominantly mucous.
Sublingual Gland
This type of salivary gland has predominantly serous cells, but mucous cells are also present. Mucous cell-containing acini are capped by serous demilunes (“bonnet”). Myoepithelial cells control serous secretions.
Submandibular Gland
In Submandibular Glands, intercalated ducts are (LONGER/SHORTER) and striated ducts are (LONGER/SHORTER) than those in Parotid Glands.
Shorter
Longer
This is a large gland with endocrine and exocrine functions, but the bulk of it is exocrine. It has a thin layer of loose CT that forms capsules. It divides the gland into ill-defined lobules, neurovasculature and ducts extend within the septa.
Pancreas
The (ENDOCRINE/EXOCRINE) component of the Pancreas is that it synthesizes and secretes enzymes that are essential for digestion in the intestine.
Exocrine
The (ENDOCRINE/EXOCRINE) component of the Pancreas is that it synthesizes and secretes hormones (insulin and glucagon) into the blood. These regulate glucose, lipid, and protein metabolism.
Endocrine
The exocrine Pancreas has serous acini as the functional unit and is structurally unique because they contain _______ _______ _______.
Pancreatic Acinar Cells
For the exocrine Pancreas, the intercalated duct begin within the acinus. ________ ________ are duct cells inside the acinus. They are continuous with the low cuboidal epithelium of the intercalated duct, and secrete HCO3-, Na+, and H2O which alkalinizes secretions.
Centroacinar Cells
For this portion of the Pancreas, the hallmarks include the following:
- Acinar cells stain intensely
- Centroacinar cells stain lightly
- Pancreas often confused with Parotid
Exocrine Pancreas
Pancreatic Acinar Cells have a well-developed RER, prominent golgi apparatus, and apical domain of ________ granules.
Zymogen
Zymogen granules within Pancreatic Acinar Cells contain about 20 different pancreatic proenzymes. List a few of these and state their function.
Trypsinogen, Chymotrypsinogen – digest proteins
Amylolytic enzymes (a-amylase) – digest carbohydrates
Lipases – digest lipids
Deoxyribonuclease, Ribonuclease – digest nucleic acids
A protein-rich diet will (INCREASE/DECREASE) synthesis of proteases in Pancreatic Acinar cells.
Increase
A carbohydrate-rich diet will (INCREASE/DECREASE) synthesis of amylases, and (INCREASE/DECREASE) synthesis of proteases.
Increase
Decrease
The endocrine Pancreas contains spherical masses of endocrine cells called _______, surrounded by thin reticular capsule. These contain several hundred cells, and arise from endodermal epithelial outgrowths.
Islets
What type of cells are in pancreatic islets, and what do they secrete?
Alpha cells = Glucagon
Beta cells = Insulin (most abundant)
Delta cells = Somatostatin (least abundant)
PP cells = Pancreatic polypeptide
The gland is enclosed in thin CT capsule lined with mesothelium of visceral peritoneum that is lacking where it directly adheres to the diaphragm and other organs.
Liver
These are liver cells that function in metabolism, storage, and bile production (exocrine). They are arranged in cellular ‘cords’.
Hepatocytes
The liver structure varies in regard to its functional unit, which are…
Hepatic Lobule
Portal Lobule
Liver Acinus
These are large, polygonal cells with eosinophilic cytoplasm and microvilli. They contain large, spherical nuclei with many being binucleate. Most are tetraploid. There are numerous peroxisomes and lysosomes, extensive sER, and large golgi.
Hepatocytes
Hepatocytes secrete _______, which is a mixture of water, bile salts and pigments, phospholipids, and electrolytes. It functions in fat absorption, and excretion of cholesterol, bilirubin, iron, and copper.
Bile
Hepatocytes drain into ________ ________, which is a canal lined with cholangiocytes located between adjacent hepatocytes. These join to eventually contribute to _______ _______.
Bile Canaliculus
Biliary Tree
Liver parenchyma is organized as ________ ________. Hepatocytes form irregular plates radiating from a central vein, and these plates are supported by a stroma of reticular fibers. Plates are separated by sinusoids.
Hepatic Lobules
Peripheral angles of each hepatic lobule contains a portal triad in fibrous CT. This triad is…
1) Venule branch of portal vein (increased nutrients, decreased oxygen)
2) Arteriole branch of the hepatic artery (supplies oxygen)
3) Bile ductules (1-2, branches of the bile conducting system)
T/F. Blood and bile flow in the same direction.
False. Blood and bile flow in opposite directions.
These are brown-staining “stick” like structures located in between hepatocytes.
Bile Canaliculi
These are anastomosing capillaries that perfuse hepatocytes with portal and arterial blood. They contain Kupffer cells and Hepatic Stellate cells (Ito cells).
Hepatic Sinusoids
These are stellate macrophages within the endothelium of hepatic sinusoids. They are larger than the endothelial cells and detect and phagocytose effete erythrocytes. They distinguish the hepatic sinusoid.
Kupffer Cells
These are cells within hepatic sinusoids that have small lipid droplets that store Vitamin A and other fat-soluble vitamins.
Hepatic Stellate Cells (Ito Cells)
This is located between hepatocytes and sinusoidal epithelium (discontinuous capillaries). It creates a potential space for exchange of materials between blood and hepatocytes. Also facilitates uptake and release of nutrients, proteins, and potential toxins.
Perisinusoidal Space (of Disse)
In the Perisinusoidal Space (of Disse), _________ project into this space. Plasma fills the space and directly bathes ________, increasing surface area available for material exchange.
Microvilli
Microvilli
These are an anastomosing network of channels formed by hepatocyte plates that end near portal triads. Transport Bile.
Bile Canaliculi
Bile flow occurs from the center of the portal lobule to the periphery. Bile Canaliculi drain into _______ _______ _______, composed of cuboidal epithelial cells called ________.
Canals of Hering
Cholangiocytes
Describe the pathway of bile, beginning with the bile canaliculi.
Bile Canaliculi —>
Canals of Hering —>
Bile Ductules (merge and enlarge) —>
Right and Left Hepatic Ducts
This is a triangular block of tissue that can be seen by drawing an imaginary line between 3 central veins. It outlines the bile drainage pathway from adjacent lobules into the same bile duct. The central axis is the bile duct (portal triad).
Portal Lobule
This is diamond-shaped and occupies parts of adjacent classic lobules. Hepatocytes are “arranged” in concentric zones around a short axis. Based on oxygen gradient along sinusoids of adjacent lobules.
Liver Acinus
In _______ _______, the flow of arterial blood creates a gradient of oxygen and nutrients. Cells within each “zone” have different metabolic functions and distribution of hepatic enzymes. This explains distribution of liver damage resulting from ischemia and/or exposure to toxic substances.
Liver Acinus
***Zone 1 has most oxygen/nutrients and decreases down to Zone 3!
This is a sac-like structure that stores and concentrates bile and releases it into the duodenum after a meal.
Gallbladder
The gallbladder has ________ ________ where it is against the liver, but a ________ where it is exposed to peritoneal cavity.
External Adventitia
Serosa
These are deep diverticula of the gallbladder mucosa that may extend through the muscularis externa. They develop as the result of hyperplasia and herniation of epithelial cells through the muscularis externa.
Rokitansky-Aschoff Sinuses
Rokitansky-Aschoff Sinuses (gallbladder) may accumulate bacteria, causing chronic inflammation and increasing the risk for…
Gallstones
