digestive system 2014

8/12/2019 Digestive System 2014

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dr. Alya Amila Fitrie, M.Kes, Sp.PADepartment of Histology

Faculty of MedicineUniversity of Sumatera Utara

2014


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Lip

Palate

Tongue

OralCavity

Esophagus

Stomach (Cardia, Fundus andCorpus, Pylorus)

Small intestine (Duodenum,Jejunum, Ileum)

Large Intestine (Caecum,Appendix, Colon,)

Rectum

Anal Canal)

AlimentaryCanal

SalivaryGland

Liver

Gallbladder

Pancreas

Glands


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3 regions:

External aspects is covered with thin skin

Vermillion Zone

The pink region of the lip

is covered with thin skin, devoid sweat gland and hair follicles

Mucous aspect

is covered by stratified squamous non keratinized ep.

Sub mucosa is composed of dense and loose connective

tissue. They have dense vascularization

Muscle: skeletal muscle


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Crown, cervix, root

Mineralized: Enamel, Dentin,

Cementum

Periodonsium: Gingiva, Alveolus,Periodontal ligament

Pulp chamber: Connective tissue,

vascular, lymph, nerve


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Hard palate

str squamouskeratinized/parakeratinized ep,irregular

collagenousCT, and bonyshelf

Soft palate

str squamousnonkeratinized ep, denseirregular CT,minor

salivaryglands, andbony shelf

Uvula

str squamousnonkeratinized ep,areolar CT,muscle


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Dorsal surface : Lingual papillae

Filiform papillae : Str squamous

keratinized ep

Fungiform papillaeFoliate papillae (degenerate at 3 y old)

Circumvalate papillae : Von Ebner

glands produces lipaseIntrinsic and extrinsic skeletal muscle


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Papila filiformis

Papila foliate

Papila

fungiformis

Papila

circumvallate


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Sensory organs, perception of

taste. (In fungiform andcircumvalate papillae)

Taste pore

Oval structure, composed of 60 80 spindle-shaped cells, pale.Microvili protrudes from tastepore Basal cells (type IV cells)

Dark cells (type I cells)

Light cells (type II cells)

Intermediate cells (type III cells)

Nerve fibers form synapticjunctions w/ type I, II, III cells


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MUCOSA : Epithelium, Laminapropria (glands, lymph vessel

and nodules, richlyvascularized), Muscularis

mucosa

SUBMUCOSA : Connectivetissue layer (Dense, irregularfibroelastic CT: glands (+) in

oesophagus n duodenum)blood&lymphatic vessels,

Submucosal plexus(Meissners)

MUSCULARIS EXTERNA :Most consist of smoothmuscle w/ myenteric(Aurbacchs) plexus)

SEROSA & ADVENTITIA

Intraperitoneal : serosa

Retroperitonea : adventitia


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Mucosa Submucosa

Muscularis externa

Serosa/

Adventitisa


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Enteric Nervous System Meissners submucosal plexus Controlling secretory, mucosal movement, blood flow

regulation

Auerbachs myenteric plexus Peristaltic Motility functions

Parasympathetic and Sympathetic Nerve Parasympathetic Stimulates peristalsis; inhibits sphincter muscle; triggers

secretion

Sympathetic Inhibit peristalsis; activate sphincter muscles


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Epithelium

Lamina Propria

Muscularis mucosae

Submucosa

Muscularis Externa

Mucosa

Esophageal glands

Inner circular layer

Outer longitudinal layer


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Mucosa

Submucosa

Muscularis Externa

Serosa


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Epithelium: simple columnar ep

Mucus layer/visible mucus; bicarbonate ion

Gastric pit/Foveola gastrica Surface lining cells Regenerative/stem cells

Lamina propria

Loose CT, vascular >>> Houses gastric/fundic/oxyntic glands Surface lining cells Mucous neck cells Regenerative (Stem) cells Parietal (Oxyntic) cells

Chief (Zymogenic) Cells DNES Cells/APUD/Enteroendocrine/Argentaffin Cells

Muscularis mucosae

3 layers: inner circular; outer longitudinal; outermost circular(occasionally)


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SUBMUCOSA

Dense, irregular CT

Richly vascularized n lymphoid tissueSubmucosal plexus

MUSCULARIS EXTERNA

Innermost oblique layer, middle circularlayer, outer longitudinal muscle layer

Auerbachsmyenteric plexus

SEROSA

Thin, loose CT covered by simple

squamous ep


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Cardiac Gastric pit depth is shallower

Highly coiled glands

Cell population: mostly surface-lining cell, some mucous neck

cells, a few DNES and Parietalcell, but no chief cells

Pylorus Gastric pit deeper

Highly convoluted and tend tobranch

Same as cardiac; but mostlymucous neck cells


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REGION CELL TYPES

ISTHMUS Surface-lining cells and few DNES

cells

NECK Mucous neck cells, Stem cells,

parietal cells, and few DNES cellsBASE Chief cells, occasional parietal

cells, and few DNES cells


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Produced thick mucus layer

Apical cell Glycocalyx-covered, short, stubbymicrovili

Secretory granules

Lateral cell

Zonula occludens n adherensBasally nucleus


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Columnar, resemble surface-lining cells

Produce soluble mucusand lysozymeto lubricate gastric contents

Predominat in pyloric


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In the base of pits but more numerousin the neck

Columnar

Have little heterochromatin anddisplay large nucleolus


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Large, round to pyramid-

shapedMainly in upper half of

fundic glands

Produce HCl and gastric

intrinsic factor

Eosinophilic cytoplasm

Invaginations apical

plasmalemma to formintracellular canaliculi

Tubulovesicular system


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Columnar with basophilic

cytoplasm, basally locatednuclei, apical secretorygranules (pepsinogen)

Rich RER, Golgi apparatus,

but a few lysosomesMicrovilli

Secretion of pepsinogen isinduced by both neural and

hormonal, triggered bysecretinbinding to thereceptor (in basal cell)


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Releases secretory granulesto lamina propria Paracrine

Endocrine

Neurocrine

13 different secretorygranules types

2 types Closed type

Open type Microvili monitor luminal

contents


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Modifications of the Luminal Surface

Transversefolds ofsubmucosaand mucosa

that formsemicircularto helicalelevations

Plicaecirculares(valves ofKerckring)

Epitheliallycovered,finger-like oroak leaf-likeprotrusionsof laminapropria

Vili

Modificationsof apical ofintestinalepithelium

cellmembrane

Microvili


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Duodenum

Brunners (duodenal) glands in submucosa

Jejunum

Plicae circulares (Valves of Kerckring)

Ileum

Peyers patch


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Jejunum

Ileum


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The most numerousTall cell with

basally located

nucleus, brush

border (microvili),

and cell junction

For terminal

digestion and

absorptions of

water and nutrients


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Unicellular glands

Produced mucinogen


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Squamous like cell above the lymphoid nodule

Important for defense mechanism


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Large,

eosinophilic,

apical secretorygranules

lysozyme

Pyramid-shapecell in bottom of

crypts Lieberkuhn


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Appendix

Caecum and Colon

Rectum and Anal Canal


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Mucosa Epithelium: simple columnar Lamina propria Richly endowed crypths of Lieberkuhn No Paneth cells; surface absorptive cells >>>>> Goblet cells >>>, DNES

>

SubmucosaMuscularis externa 2 layers: inner circular; outer longitudinal

Outer longitudinal layer is not continous but is gathered into 3fascicles: taenia coli

Serosa Appendices epiploicae: fat-filled pouches


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Taenia Coli


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Rectum resembles colon but the crypts of

Lieberkuhn are deeper and number fewer per

unit area


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Mucosa Epithelium: simple cuboidal from rectum to pectinate line Str squamous nonkeratinized: from pectinate line to external anal

orifice Str squamous keratinized: epidermis at anus

Lamina propria houses anal glands (at rectoanal junction) andcircumanal glands (distal end of anal canal)

Submucosa Fibroelastic tissue houses 2 venous plexus: internal and external

hemorrhoidal plexus

Muscularis externa Inner circular layer becomes thickened at pectinate line to form

internal anal sphincter muscle

External anal sphicter muscle comes from pelvis


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Thank you

digestive system 2014

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