Digestive gland
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In the name of God. Digestive gland. Dr. Zahiri. Digestive Glands. Digestive glands are consist of: Salivary glands Pancreas Liver Gall bladder. Salivary Glands. minor (Accessory ) salivary glands pairs of major (main) salivary glands Three pairs of major salivary glands are:

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Digestive gland

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Digestive gland

In the name of God

Digestive gland

Dr. Zahiri


Digestive gland

Digestive Glands

Dr. Maria Zahiri

Digestive glands are consist of:

  • Salivary glands

  • Pancreas

  • Liver

  • Gall bladder


Digestive gland

Dr. Maria Zahiri

Salivary Glands

  • minor (Accessory) salivary glands

  • pairs of major (main) salivary glands

  • Three pairs of major salivary glands are:

    • Submandibular glands

    • Sublingual glands

    • Parotid glands


Digestive gland

Salivary Glands

Dr. Maria Zahiri

  • capsule and septa

  • that organize the glands into lobes and lobules


Digestive gland

Dr. Maria Zahiri


Digestive gland

Salivary Gland Cells

Dr. Maria Zahiri

  • 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


Digestive gland

Dr. Maria Zahiri


Digestive gland

Dr. Maria Zahiri

  • Mucous cells

  • cuboidal or pyramidal

  • heterochromatic basal flattened nucleus

  • Apical cytoplasm is pale

  • Theyhave less RER, fewer mitochondria but greater GA


Digestive gland

Dr. Maria Zahiri


Digestive gland

Dr. Maria Zahiri

  • Organized as acinus or demilune that secrete proteins, polysaccharides and ptyalin


Digestive gland

Dr. Maria Zahiri

  • Ducts system

  • Intercalated duct

  • smallest branches

  • short, cuboidal or squamous cells and myoepithelial cells

  • Striated duct

  • Largerdiameter

  • cuboidal to low columnar cells which are eosinophilic, and secrete fluid and ions

  • basolateral membrane folded with Na – ATPase pump, elongated mitochondria


Digestive gland

Dr. Maria Zahiri

  • intralobularducts:

  • Striated ducts join each other and forming intralobular ductsthat are invested by more CT elements

  • interlobular ducts (excretory ducts):

  • intralobular ductsjoin 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


Digestive gland

Dr. Maria Zahiri


Digestive gland

Dr. Maria Zahiri


Digestive gland

Dr. Maria Zahiri

  • Myoepithelialcells (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


Digestive gland

Parotid Gland

Dr. Maria Zahiri

  • 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 adipose

  • tissue invaded the gland


Digestive gland

Submandibular Gland

Dr. Maria Zahiri

  • produce 60% of saliva

  • Mucous and serous acini; mucous acini with limited number of serous demilunes

  • About 80% of cells are serous (basophilic)


Digestive gland

Sublingual Gland

Dr. Maria Zahiri

  • 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


Digestive gland

Saliva

Dr. Maria Zahiri

  • 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 tissues

  • Participate in taste sensation

  • IgA, lactoferrin, lysozyme have different role against antigens and microorganisms


Digestive gland

Pancreas

Dr. Maria Zahiri

  • 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


Digestive gland

Dr. Maria Zahiri


Digestive gland

Dr. Maria Zahiri


Digestive gland

Liver

Dr. Maria Zahiri

  • 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


Digestive gland

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


Digestive gland

Dr. Maria Zahiri


Digestive gland

  • classical lobule

  • blood flow from periphery to center of lobule

  • Bile flow in opposite direction in small intercellular spaces known as bile canaliculi

  • Portal lobule

  • Is 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)


Digestive gland

Dr. Maria Zahiri


Digestive gland

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)

  • Microvilliof hepatocytes occupy much of the space

  • Type III collagen that is present in space support lining cells(no basal lamina)


Digestive gland

Cells

  • 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, eosinophilicwith 1 or 2 spherical nuclei,


Digestive gland

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


Digestive gland

  • Liver

  • Sinunosoidal 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

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


Digestive gland

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


Digestive gland

Dr. Maria Zahiri

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