digestive gland dr. zahiri in the name of god. digestive glands digestive glands are consist of: ...
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Digestive gland
Dr. Zahiri
In the name of God
Dr. Maria Zahiri
Digestive GlandsDigestive glands are consist of:
Salivary glands
Pancreas
Liver
Gall bladder
Dr. Maria Zahiri
Salivary Glands
• minor (Accessory) salivary glands • pairs of major (main) salivary glands
Three pairs of major salivary glands are:Submandibular glandsSublingual glandsParotid glands
Dr. Maria Zahiri
Salivary Glands
capsule and septa that organize the glands into lobes and lobules
Dr. Maria Zahiri
Dr. Maria ZahiriSalivary Gland Cells Serous cells produce proteins pyramidal cells spherical euchromatic nucleus Cytoplasm is basophilic (RER, Golgi apparatus) Apically located granules that are usually eosinophilic Many basal mitochondria
Dr. Maria Zahiri
Dr. Maria Zahiri
Mucous cells
cuboidal or pyramidalheterochromatic basal flattened nucleusApical cytoplasm is paleThey have less RER, fewer mitochondria but greater GA
Dr. Maria Zahiri
Dr. Maria Zahiri
• Organized as acinus or demilune that secrete proteins, polysaccharides and ptyalin
Dr. Maria Zahiri
Ducts system
Intercalated duct smallest branches short, cuboidal or squamous cells and myoepithelial cells
Striated duct Larger diameter cuboidal to low columnar cells which are eosinophilic, and secrete fluid
and ions basolateral membrane folded with Na – ATPase pump, elongated
mitochondria
Dr. Maria Zahiri
intralobular ducts:Striated ducts join each other and forming intralobular ducts that are
invested by more CT elements
interlobular ducts (excretory ducts):intralobular ducts join each other and forming larger caliber ducts
known as interlobular ducts (excretory ducts)
Excretory duct have large diameter, large lumen, cuboidal or columnar cells, located outside of lobules
Dr. Maria Zahiri
Dr. Maria Zahiri
Dr. Maria Zahiri
Myoepithelial cells (Basket cells)
have large processes which form desmosomal contact with acini and ducts cells,
Their processes are rich in actin and myosin
have a common basal lamina with acinar cells
They attach to basal lamina by hemidesmosome
Dr. Maria ZahiriParotid Gland The largest salivary gland produce 30% of saliva capsule & many septa divided the glands into lobes and lobules serous cells After 40 year of age adiposetissue invaded the gland
Dr. Maria Zahiri
Submandibular Gland produce 60% of saliva Mucous and serous acini; mucous acini with limited number of
serous demilunes About 80% of cells are serous (basophilic)
Dr. Maria Zahiri
Sublingual Gland It is very small that produce 5% of total saliva Mostly mucous cells in acini with some serous demilunes Produce mix saliva but mostly mucous saliva
Dr. Maria ZahiriSaliva
Saliva includes water, enzymes, IgA, mucous, ions
Moisten and lubricate food for swallowing
Enzymes like amylase and lipase to begin digestion
Saliva has protective effect on oral cavity tissuesParticipate in taste sensation
IgA, lactoferrin, lysozyme have different role against antigens and microorganisms
Dr. Maria ZahiriPancreas is a mixed exocrine and endocrine gland Thin capsule with septa between lobules Exocrine part organized similar to parotid gland Endocrine part are islets of Langerhans scattered among the
excretory units Centroacinar cells occupy the lumen of the acini, these cells are
beginning of the duct system Centroacinar cells are pale, low cuboidal
Intercalated ducts, intercalated ducts, Intralobular ducts, and interlobular ducts
Dr. Maria Zahiri
Dr. Maria Zahiri
Dr. Maria Zahiri
Liver
largest gland in the body (1500 gr) has endocrine and exocrine functions
Receives portal blood from intestine via portal vein and oxygenated blood from hepatic arteries
Dr. Maria Zahiri
Liver hepatocytes Liver has a lobular organization Classical lobule:
hepatocytes arranged as an hexagon
Portal area (triad): is where three classical lobules are in contact with each other, more
CT elements present, houses branches of hepatic artery, tributaries of portal vein, interlobular bile ducts, and lymph vessels
Dr. Maria Zahiri
classical lobule blood flow from periphery to center of lobuleBile flow in opposite direction in small intercellular spaces known as bile canaliculi
Portal lobuleIs a triangular region that portal area is located in its center and central veins form apices of the triangle
Hepatic acinus (acinus of Rappaport)is diamond-shaped, a distributing artery located in center of acinus, three regions of parenchyma surrounding the artery(zone I, II, III)
Dr. Maria Zahiri
Liver The space between the anastomosing plates of hepatocytes are
occupied by hepatic sinusoids
Sinosuidal lining cells are fenestrated are not in contact with each other
They prevent direct contact between blood and hepatocytes
Resident macrophages known as Kupffer cells associated with lining cells
The space that separates sinusoidal lining cells from hepatocytes is called perisinusoidal space (space of Disse)
Microvilli of hepatocytes occupy much of the space Type III collagen that is present in space support lining cells(no basal
lamina)
Fat storing cells ( known as Ito cells or Stellate cells) may present in Disse space and store vitamin A
Pit cells which are natural killer cells also may be seen in space of Disse
Hepatocytes are polygonal
forming anastomosing plates of one to two thickness cells, eosinophilic with 1 or 2 spherical nuclei,
Cells
In lateral domain bile canaliculi form between two cells, microvilli, Na-K ATPase and gap junctions are common characteristics of lateral domain
Bile canaliculi between hepatocytes leading to hepatic ducts with simple cuboidal epithelium
Cells
LiverSinunosoidal domains of cell membrane have many microvilli protrude to perisinusoidal space (of Disse), endocrine secretion of hepatocytes release here
Bile secreted from hepatocytes into bile canaliculi contains water, ions, bile salts and acids, phospholipids, cholesterol, & bilirubin
Liver Functions
Glycogen storage Lipid metabolism Vitamin storage (A, D, B12 ) Bile production (Bile acids solubilize lipids and aid
digestion) Detoxification of drugs and toxins in SER Synthesis of plasma proteins (albumin) Metabolism of lipid, carbohydrate, proteins Erythrocyte breakdown (Bilirubin formed in breakdown
of RBC) Complex IgA with secretory component
Gall Bladder
Mucosa : simple columnar epithelium Epithelial layer is highly folded lamina propria: loose CT
Smooth muscle layer is composed of thin obliquely oriented fibers with perimuscular connective tissue
Serosal and adventitial membrane Stores and concentrates 30-50 ml bile Cholecystokinin and acetylcholine stimulates contraction to force
bile into small intestine
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