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HISTOLOG Y OF GIT BY DR. MUDASSAR ALI ROOMI (MBBS, M. Phil.)
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1st Lec on GIT Histology by Dr Roomi

Apr 06, 2018

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    HISTOLOGY OF

    GIT

    BY

    DR. MUDASSAR ALI ROOMI (MBBS, M. Phil.)

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    TWO MAIN COMPONENTS OF DIGESTIVE SYSTEM:

    1. The digestive tract

    (alimentary canal)

    2. Major glands

    associated with the

    tract (salivary glands,

    pancreas, liver

    alongwith biliary

    passages)

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    Digestive tract

    Anatomically divided into

    two parts:

    1. The oral cavity.

    2. The tubular digestive

    tract which includes

    esophagus, stomach,

    small intestine and

    large intestine.

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    Oral cavity

    It is irregular space

    bounded by the lips,

    cheeks and palate.

    It contains tongue,

    gums and teeth.

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    LIPS

    Core of lips: made by

    skeletal muscles and

    fibro-elastic C.T.

    Three surfaces:

    1. Cutaneous surface

    2. The red area

    3. Oral surface.

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    Histology of Lips

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    Histology of Lips

    1. Cutaneous surface:

    Covered by ordinary thin skin which contain hair follicles, sebaceous glands and sweat

    glands.

    Epithelium= st. sq. keratinized

    2. The red area (transitional zone):

    covered by modified skin. St sq non-keratinized epithelium.

    Thick st. lucidum.

    Numerous tall vascular dermal papillae which project into the epidermis.

    Papillae are very vascular.

    numerous sensory nerve endings (lips are very sensitive!).

    No hair follicles, sebaceous or sweat glands

    3. Oral surface:

    Covered by the oral mucosa

    Epith= st. sq. non- keratinized. It is thicker than that of skin area.

    tall papillae in the lamina propria

    labial salivary glands (mucous simple tubulo-alveolar glands)

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    TONGUE

    It is a mass of sk. Musclescovered by the mucousmembrane.

    Muscles: running in all the 3

    dimensions.

    Epithelium:

    1. On ventral (lower) surface:

    st. sq. non-keratinized

    2. On dorsal (upper) surface:partially keratized,otherwise it is mainly st.sq. non- keratinized maily.

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    TONGUE

    SURFACES OF TONGUE:

    1. Dorsal surface: roughdue to presence of

    lingual papillae,irregular, divided intoanterior (2/3) andposterior (1/3) by V-shaped sulcusterminalis.

    2. Ventral surface

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    LINGUAL PAPILLAE

    These are projections on the anterior 2/3 of thedorsal surface of the tongue.

    Make the dorsal surface rough.

    Formed by: central core of C.T. And covered by st.sq. epithelium.

    Main types of lingual papillae are:

    1. Filiform papillae

    2. Fungiform papillae3. Circumvellate papillae

    4. Foliate papillae.

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    LINGUAL PAPILLAE

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    ANTERIOR REGION OF TONGUE

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    LINGUAL PAPILLAE

    1. Filiform papillae:

    most numerous,

    finger like projections,

    smallest,

    distributed over entire ant 2/3 of tongue,

    contain no taste buds,

    covered by st sq keratinized epith,

    filiform= thread like

    2. Fungiform papillae:

    scattered singly,

    fungiform= shaped like mushroom, covered by st sq non-keratinized epith,

    a few taste buds on them

    3. Circumvellate papillae:

    8-12 in number

    Located just anterior to V shaped sulcus terminalis

    Numerous taste buds in the walls of trench.

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    LINGUAL PAPILLAE

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    ANTERIOR REGION OF TONGUE

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    GLANDS OF TONGUE

    1. Anterior lingual glands:

    pair,

    mixed seromucous,

    near the tip of tongue,

    duct open on the ventral surface.2. Glands of von Ebner:

    purely serous,

    located in the region of circumvellate papillae,

    ducts open in the trenches of circumvellate papillae,

    3. Mucous glands of the root: Numerous, small, purely mucous.

    Located near the posterior region of tongue.

    Ducts open in the crypts of the lingual tonsils.

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    TASTE BUDS IN THE TRENCH OF CIRCUMVELLATE PAPILLAE

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    TASTE BUDS

    Receptors for tastesensation.

    Location: dorsal surfaceof tongue, soft palate,

    epiglottis. on H/E stain, taste bud

    appears as oval, palestaining body (30-50 umwide).

    50-90 cells One taste pore (gustatory

    pore).

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    TASTE BUDS

    TYPES OF CELLS in the tastebuds:

    1. Neuroepithelial cells:

    Tall columnar cells

    Basal portion of cellscontain synaptic vesicles.

    2. Sustancular cells:

    Function is to support

    3. Basal cells:

    Stem cells