Download MBBS Digestive System I Lecture PPT

Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Digestive System I Lecture PPT


DIGESTIVE SYSTEM I
INTRODUCTION

? CONSISTS OF TWO GROUPS OF ORGANS

? 1)GIT or alimentary tract--extend from oral

cavity to anal canal.

? 2)Accessory digestive organs--these are

teeth, tongue, salivary glands, liver, gall

bladder and pancrease.
TONGUE

? Accessory digestive organ.
? Composed of skeletal muscle covered with mucous

membrane.

? Lining mucosa stratified squamous epithelium and

lamina propria.

? An inverted V-shaped grooved (sulcus terminalis)

divide dorsal aspect of tongue into anterior2/3 and

posterior 1/3.

? Dorsal aspect of root of tongue contains lingual

tonsil.

? LINGUAL PAPILLAE
? The anterior 2/3 of dorsal surface is covered with

specialization of epithelium called lingual papillae.

? Are projection of lamina propria
? Covered with stratified squamous epithelium which

may be keratinized.

? FOUR TYPES--

i) Filiform

ii) Fungiform

iii) Circumvallate

iv) Foliate
? FOLIATE PAPILLAE ARE NOT WELL DEVELOPED IN

HUMAN

? FILIFORM PAPILLAE
? Cone-shaped
? Mostnumerous
? Anterior2/3ofthetongue.
? Tipsarekeratinized
? No taste Buds

? FUNGIFORM PAPILLAE
? Mushroomshaped
? Lessnumerous
? Founddistributedamongthefiliformpapillae
? Has taste buds
? CIRCUMVALLATE PAPILLAE

? 8?16papillaelocated(onav-shapedline)just

anteriortothesulcusterminalis.

? Largecircularpapillae

? Serousacini(calledVon Ebner's glands)open

intothegroovetodissolvefoodparticles,sohelp

tasting

? Hastastebuds
? TASTE BUDS
? Neurosensory epithelial structure embedded in

the surface epithelium of tongue.

? Also presents in the epiglottis, soft palate and

oropharynx.

? Onion-shapedstructuresintheepitheliumof

lingualpapillaee.g.fungiformand

circumvallatepapillae.

? Theirapicalendshasopeningcalledtaste pore

? CELLS IN THE TASTE BUDS--Three types
? i)Neuroepithelial or receptor cells
? ii)Supporting cells
? iii)Basal or stem cells

? stimulationofthetastecellsleadstothe

stimulationofgustatorynervefibersand
receivingsweet,salty,bitter,andsour
sensations.

? Muscles of the tongue
? The core of the tongue striated muscle.

? Muscles fibres arranged in transverse,

longitudinal and vertical bundles.

? In between the muscle bundle loose

connective tissue, adipose tissue and lingual

gland are present.

SALIVARY GLANDS

? Major glands

? Lie completely outside the alimentary tract &

connected to it by an excretory duct.

? Compound alveolar or tubuloalveolar in type.

? Parotid
? Submandibular
? sublingual.
? Minor glands

? Small salivary glands situated in the mucous

membrane of:

? Lip (labial)
? Cheeks (buccal)
? Soft palate (palatine)
? Tongue (lingual)
Functions of Salivary glands

? Secrete saliva composed of water, mucus,

proteins, salts, salivary amylase (ptyalin),

immunoglobulins (IgA) & lactoperoxidase.

? Serves to moisten food.

? Lubricates & moistens oral mucosa and lip.

? Initiates the digestion of carbohydrates.
Basic organization

? Consists of two components:--
? i) Connective tissue component
? ii) Parenchymal components (duct and acini)

? Connective tissue capsule surrounded parotid and

submandibular gland.

? Septa divides gland into lobes and lobule.

? Septa forms a medium through which nerves,

blood vessels and ducts passes.


Duct system
? Lining epithelium of duct system--

? Intercalated--Cuboidal

? Striated--Columnar

? Interlobular--Pseudostratified columnar

? Main excretory duct--Stratified cuboidal


Acinar system
PAROTID GLAND

? Largest salivary gland.
? Well defined capsule.
? Secretory acini--Purely serous.
? Has abundant myoepithelial (basket) cells.
? Ducts--Interlobular in connective tissue septa
? Intralobular duct in between acini
? Adipose tissue present between acini and

smaller duct.
Parotid gland
SUBMANDIBULAR GLAND

? Mixed gland
? Well defined capsule and septa.
? Secretory acini--both serous and mucous.
? Serous acini are more sometimes
? Mucous acini are capped by a layer of serous cells

called serous demilunes.

? Ducts--same
Submandibular gland
SUBLINGUAL GLAND

? Mixed salivary gland.

? No definite capsule.

? Septa divides gland into lobules.

? Secretory acini-- predominantaly mucous acini.

? Duct--intercalated and striated duct rarely seen
Sublingual gland


SEROUS

MUCOUS

SIZE OF SECRETORY END PIECE SMALL

LARGE

SIZE OF LUMEN

SMALL

LARGE

SECRETION

THIN WATERY

THIC VISCOUS

NATURE OF SECRETORY

ZYMOGEN GRANULES

MUCINOGEN DROPLETS

GRANULES

NUCLEUS

ROUND, CENTRAL

FLAT , PERIPHERAL

FUNCTION

ENZYME ACTION

PROTECTION & LUBRICATION

EXAMPLE

PAROTD GLAND

SUBLINGUAL GLAND

This post was last modified on 30 November 2021