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85 Cards in this Set
- Front
- Back
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Where are the Extrinsic Glands of the Digestive System located?
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Outside the wall of the alimentary canal
-they deliver their secretion into the lumen via a system of ducts |
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What do these Extrinsic Glands provide?
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Enzymes, buffers emulsifiers, and lubricants for the digestive tract as well as hormones, proteins, globulins (A), and numerous additional products for the remainder of the body
-they are salivary glands (parotid, sublingual, and submandibular) -pancreas -liver |
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What is the major Salivary Gland?
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Parotid Gland
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What is the characteristics of a Parotid Gland?
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They are purely serous, compound, tuboloalveolar gland
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How is the capsule of the Parotid Gland formed by?
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The continuation of the superficial cervical fascia which is mostly collagenous in nature
-They form broad bands of trabeculae (septa) that subdivide the gland into lobes and lobules |
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How are ducts formed? (step by step)
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Intercalated duct --> Striated duct --> Intralobular duct --> Interlobular duct --> Lobar duct --> Main duct
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What is the function of a Trabeculae?
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They convey blood and lymph vessels, ducts, and nerves into the substance of the gland
-often contain fat cells in older individuals |
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What are Acini?
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They are Seromucuous in character!! Even though they are said to be composed of purely serous cells
-surrounded by myoepithelial cells -their center contains the lumen |
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What are Acinar cells?
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They are Pyramidal cells whose apical aspects usually contain secretory granules
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What are the characteristics of Acinar cells?
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-nucleus is round (flattened )and basally located
-cytoplasm contains extensive RER -well developed Golgi apparatus -numerous Mitochondria |
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What are the characteristics of Myoepithelial Cells?
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-stellate shaped
-cytoplasm is difficult to discern with the Light Microscope -resemble smooth muscle cells and are CONTRACTILE! |
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What is the largest (main Parotid duct)?
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The Stensen's Duct
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The Stensen's Duct is lined by what type of epithelium?
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Simple columnar or pseudostratified epithelium
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Where does the Stensen's Duct open into?
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Into the oral vestibule at the parotid papilla
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Striated Ducts are lined by what type of epithelium?
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High Cuboidal cells
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What are the characteristics of Striated ducts?
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They have basal striations that parallel the longitudinal axis of the cell
-striations are due to deep infoldings of the basal plasma membrane which compartmentalize mitochondria |
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Which are the smallest ducts?
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Intercalated Ducts
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Intercalated ducts are lined by what type of epithelium?
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simple cuboidal epithelium
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Where do Intercalated ducts lie?
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Interposed among the acini where they constitute the initial part of the duct system
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Which glands have the longest intercalated ducts?
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The Parotid Gland
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Where can myoepithelial cells be visualized?
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at the periphery of each acinus
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The secretory granules of the Parotid land contain what type of proteins?
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Proline-rich proteins, enzymes (amylase ) and proteins with antimicrobial activity (cystatins and Hystatins)
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What surrounds the serous acini?
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Connective Tissue and blood vessels
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What is a Sublingual Gland?
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They are mixed, compound, tubuloalveolar gland
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What are Acini in Sublingual Gland?
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They are mostly mucous but capped with serous demilunes
-occasionally, purely mucous acini are present, but purely serous units are not present |
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Where are Serous Demilune Cells located?
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located peripheral to the mucous acini and deliver their secretions into their spaces between the neighboring mucus-producing cells
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Which gland contains both pure mucous and mixed secretory units?
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Sublingual Gland and Submandibular Glands
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What are poorly developed in the sublingual gland?
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Intercalated ducts
Striated Ducts |
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What does the mucous cells of the Sublingual glands secrete?
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Highly glycosylated mucins which contribute to the formation of the protective pellicle film
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What are Submandibular Glands?
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They are mixed, compound tubuloalveolar gland
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What are the Acini in Submandibular Glands composed of?
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Mostly serous acini, however, groups of mucous acini with serous demilunes are also present
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What structure is uncommon in the submaxillary gland?
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Pure mucous acini
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What is a Pellicle?
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thin protective film secreted by mucous cells
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On an average day, what is the daily production of saliva?
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1.0 to 1.2 Liters
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What are the functions of Saliva?
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-protect the oral cavity by lubrication
-control of bacterial flora by the presence of lysozyme, lactoferrin, and IgA and its cleansing action -assist in taste sensation -initiates digestion of carbs via action of its enzyme, salivary amylase |
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What is the primary secretion of saliva?
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Saliva secreted by the acini, prior to modification by the system of ducts,
-resembles extracellular fluid |
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Intercalated ducts deliver what type of ions into the saliva?
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Intercalated ducts may deliver bicarbonate ions into the saliva
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What type of Solution is Saliva?
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It is a hypotonic solution
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Which type of duct remove sodium and chloride ions from the luminal fluid and actively pump K ions into it?
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Striated Ducts
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The exocrine function of the pancreas is served by what type of cells and duct?
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Acinar Cells
Centroacinar cells Intercalated ducts |
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What does the Acinar cells of the Pancreas secrete?
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Digestive Enzymes
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What does the duct cells of the Pancreas supply?
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Alkaline buffer solution
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The endocrine portion of the pancreas is composed by what structure?
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The Islets of Langerhans
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What are Islets of Langerhans?
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They are richly vascularized spherical aggregates of cells encased by reticular fibers
-lie scattered in an apparently random fashion among the acini of the exocrine pancreas -more numerous in the tail region -composed of several cell types having different functions |
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The islets are composed of what type of cells?
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By five types of cells which can be differentiated from each other only with special stains
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What is the number one characteristic of a Pancreas?
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The Islets of Langerhans
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Is the pancreas a retroperitoneal gland or a intraperitoneal gland?
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It is a retroperitoneal gland
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What does the Pancreas produce?
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Both exocrine and endocrine secretions
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How is the pancreas subdivided?
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Head
Uncinate process Neck Body Tail |
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Which part of the pancreas contains the highest concentration of Islets of Langerhans?
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The TAIL!
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What is the capsule of the Pancreas composed of?
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Delicate connective tissue that subdivides the gland into lobules by forming numerous septa
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What does the Septa of the Pancreas convey?
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Blood and lymph vessels, nerves and ducts in and out of the gland
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Where are myoepithelial cells not present?
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They are not present in the PANCREAS
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What are Exocrine Pancreas?
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A purely serous, compound tubuloalveolar gland
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What are the Acini cells in the Exocrine Pancreas?
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They are only SEROUS whose center contain centroacinar cells
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What are centroacinar cells of the Exocrine Pancreas?
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They form the beginning of the duct system in the pancreas
-low cuboidal in shape -constitute the initial part of the intercalated duct |
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What structure leads from between acinar cells to the lumen of the acinus?
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Intercellular Canaliculi
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What are the characteristics of the Acinar Cells of the Exocrine Pancreas?
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They are exactly the same as the parotid glands
-pyramidal in shape and have around nucleus that is basally located -basal region is strongly basophilic -apical region is densely packed with secretory granules (zymogen granules) |
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What happens if Zymogen is activated?
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They will digest the Pancreas itself it is activated, therefore there is a very dangerous pathology
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Zymogens are full of?
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Inactive enzymes
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What are Characteristics of any active cell?
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-abundant ER
-extensive golgi apparatus -numerous mitochondria -many free ribosomes |
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What are the characteristics of secretory granules?
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-all membrane bound
-occasionally noted to be in the process of being released in "chains" that extend to the lumen of the acinus |
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Where do intercalated ducts empty into?
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Large Interlobular ducts
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In the exocrine pancreas, only what type of acini are present?
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Serous Acini
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What is a unique feature of the pancreatic acinus?
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Present of squamous to cuboidal epithelial known as CENTROACINAR cells
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Which type of duct is not present in the exocrine pancreas?
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STRIATED DUCTS!
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Where are Interlobular ducts located?
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between the lobules in extensive connective tissue
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Where do Interlobular ducts empty into?
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The main or accessory Pancreatic Duct
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What is the Pancreatic Duct?
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It is the main pancreatic duct which delivers the pancreatic secretions into the duodenum at the Papilla of Vater
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What two hormones are released from the Duodenum?
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Cholecystokinin
Secretin |
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What do the two hormones control?
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They control the pancreatic secretion
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What is Cholecystokinin (Pancreozymin) and the function?
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It is an enzyme released by the duodenum
-induces the acinar cells to release pancreatic juices rich in digestive enzymes -enzymes are trypsin, chymotrypsin, peptidase, pancreatic amylase, lipase, and ribo-and deoxyribonucleases |
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What is Secretin and what is its function?
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It induces the intercalated ducts to secrete large quantities of an enzyme-poor, alkaline fluid that probably functions in neutralizing the acidic chyme that enters the duodenum
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Where are Alpha cells located?
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They are preferentially positioned at the islet's periphery
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What are the characteristics of Alpha Cells?
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They have spherical, membrane-bound, electron-dense granules
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What do beta cells mostly occupy?
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Majority the center of each islet
80% cells are Beta cells in an islet |
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What are the characteristics of Granules within the Beta Cells?
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-They are membrane bound
-smaller than those of alpha cells -characterized by presence of an irregular dense core, surrounded by an electron-lucent periphery |
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What are Delta Cells?
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They are less common than the other two and may be recognized in the electron microscopy by their relatively large, electro-lucent granules
-The granules membranes are not usually well defined |
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What do Beta Cells secrete?
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Insulin
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Somatostatin is secreted by what type of cells?
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Delta Cells
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What is the function of somatostatin?
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It is a hormone that controls the release of insulin and glucagon, thus possibly reducing the volume of alkaline-rich pancreatic juices
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What cells release pancreatic polypeptide?
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PP cells
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What do Pancreatic polypeptides do?
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It is a hormone that may act to reduce the release of both enzyme-rich and alkaline-rich pancreatic secretions
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What do G cells release?
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They release gastrin
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What is the function of Gastrin?
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A hormone that functions in modulating the release of HCl by the parietal cells of the stomach
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