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Classification of Glands

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Glands Associated with the Gastrointestinal Tract Classification of Glands Classification of Glands Classification of Glands Salivary Glands There are three pairs of ... – PowerPoint PPT presentation

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Title: Classification of Glands


1
Classification of Glands
  • Glands
  • Associated with
  • the
  • Gastrointestinal Tract

2
Classification of Glands
  • Classification of Glands

3
Salivary Glands
  • There are three pairs of major salivary glands
  • Parotid
  • Submandibular
  • Sublingual
  • There are many small salivary glands in the oral
    cavity
  • Major glands are surrounded by dense connective
    tissue capsule
  • Capsule sends septa separating the parenchyma
    into lobules
  • Each lobule consists of many secretory acini and
    excretory ducts

4
Secretory Part of The Glands
  • Serous cells are characteristically protein
    synthesizing cells, pyramidal in shape with broad
    base and narrow apical region.
  • Mucus cells are basically cuboidal to columnar
    have condensed, basally located flat nuclei. They
    are characteristically mucus synthesizing cells
    and they form tubules
  • Acini are surrounded by myoepithelial cells
  • Serous demilunes are serous cells capping the
    mucus acini

5
Glandular Duct System
  • Intercalated duct
  • Striated duct
  • Interlobular duct
  • Intralobular duct
  • Main duct

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7
Parotid Gland
  • Branched acinar
  • Capsule sends septa dividing it to
  • lobes
  • Lobules
  • Serous acini
  • Secretes proteins
  • amylase, proline-rich protein
  • Acinar cells

8
Submandibular Gland
  • A mixed gland
  • Branched Tubuloalveolar
  • Capsule
  • Lobules
  • Serous Demilunes
  • Secrete amylase, proline-rich protein
  • and lysozyme
  • Ducts

9
Sublingual Gland
  • A mixed gland
  • Branched tubuoalveolar
  • Capsule
  • Lobules
  • Serous Demilunes
  • Secrete amylase,
  • proline-rich protein
  • and lysozyme

10
Pancreas
  • It is mixed gland
  • Looks like parotid gland
  • Islands of Langerhans
  • No striated ducts
  • Centroacinar cells

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12
Liver
  • It is divided into lobules
  • Classical
  • Portal lobule
  • Liver acinus
  • Classical lobule is hexagonal
  • in shape
  • Central vein
  • Portal triads
  • Perisunusoidal space (of Disse)

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15
  • Portal Triads

    A
    branch of the portal vein, a branch of the
    hepatic artery and a branch of the bile duct -
    are called portal triads. Portal triads are a key
    feature of the organization of the liver. Portal
    triads are embedded in interlobular connective
    tissue.

16
  • The Liver Lobule


    The "classical" liver lobule is
    hexagonal(six-sided). It is delimited by
    interlobular connective tissue (only little, if
    any, visible in humans plentiful in e.g. pigs).
    In its corners we find the portal triads.

17
  • In cross sections, the lobule is filled by cords
    of hepatic parenchymal cells, hepatocytes, which
    radiate from the central vein and are separated
    by vascular sinusoids.
    Hepatocytes are separated from the bloodstream
    by a thin fenestrated simple squamous epithelium,
    which lines the sinusoids.

18
  • Between the hepatocytes and the epithelial cells
    is a narrow perisinusoidal space (of Disse).
    Contents of the blood plasma can freely enter the
    perisinusoidal space through the fenestrations of
    the epithelium lining the sinusoids. Fixed
    macrophages, Kupffer cells, are attached to the
    epithelium.

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21
  • The liver lobule is drained by the central vein,
    which open into the sublobular veins of the
    liver. These in turn coalesce to form the hepatic
    veins. They run alone through the tissue, are
    usually covered by connective tissue and
    eventually empty into the inferior vena cava.

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23
Liver Functions
  • Protein synthesis
  • Bile secretion
  • Metabolic storage
  • Metabolic functions
  • Detoxification

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25
  • a

26
  • Gallbladder
  • The gallbladder is a hollow, pear-shaped organ
    attached to the lower surface of the liver. It
    can store 30 to50 mL of bile.
  • The wall of the gallbladder consists of a
  • mucosa composed of simple columnar epithelium
    and lamina propria, a
  • layer of smooth muscle,
  • a perimuscular connective tissue layer, and
  • a serous membrane

27
  • The mucosa has abundant folds that are
    particularly evident when the gallbladder is
    empty.
  • The epithelial cells are rich in mitochondria
  • . All these cells are capable of secreting small
    amounts of mucus. Tubuloacinar mucous glands near
    the cystic duct are responsible for the
    production of most of the mucus present in bile.

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30
  • The main function of the gallbladder is to store
    bile, concentrate it by absorbing its water, and
    release it when necessary into the digestive
    tract. This process depends on an active
    sodium-transporting mechanism in the
    gallbladder's epithelium.

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