4+5 tissue types and epithelial tissue.ppt

7/21/2019 4+5 tissue types and epithelial tissue.ppt

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Tissue types

Lect. # 4+5

Dr. Essam Qnais


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Epithelial tissue

Epithelial tissue is present in two forms 1-

as sheets of contiuous cells that co!er

the "oy on its e$ternal surface an line

the "oy on its internal surface an %- as

lans which oriinate from in!ainate

epithelial cells.


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&unctions of epithelial tissue

1- co!erin an linin of surfaces e.. s'in

(protection)

%- absorptione.. intestines or certain'iney tu"ules

*- secretion of mucus hormones , etce.. epithelial cells of lans

4- sensation(neuroepithelium) e.. taste"us retina of the eye.

5- contractione.. myoepithelial cells


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riin of epithelial tissues

(eri!e from any em"ryonic layer)

1- ectoderm layer

(epithelium that lines the s'in mouth nosemammary lan an anus)

%- endoderm layer

(epithelium that lines respiratory systemiesti!e tract an the lans of the

iesti!e tract (li!er pancreas)) *- mesoderm layer

(epithelium that lines the "loo !essels)


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Epithelial tissues are classifie

accorin to

1- the num"er of cell layers "etween the "asal

lamina an the free surface

Single layer

Several layer

Basal lamina


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asal lamina

asement mem"rane is well staine "y the /0 reaction.


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asal laminae an "asement

mem"ranes The basement

membraneseen with

liht microscopy is shown

"y electron microscopy to

"e compose of thebasal lamina ela"orate

"y epithelial cells an

lamina reticularis

manufacture "y cells ofconnecti!e tissue


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asement mem"rane


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Basal lamina (seen with EM)- lamina lucia (23 collaenlaminin entactin interins an

proteolycan) - lamina ensa (23 collaen

coate with proteolycan anaminolycosie. ontains alsofi"ronectin)

- &unctions of "asal lamina

1- support %- reulatese$chanes of molecules *- cellto cell interaction 4- reulatecell proliferation anifferentiation.

Lamina reticularisis

manufacture "y fi"ro"lastsan is compose of type 2 an222 collaen an is responsi"lefor affi$in the lamina ensa tothe unerlyin T


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asement

mem"ranein iney


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asement

mem"rane

in iney


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%- the shape (morpholoy) of the component cells

(the shape of the nuclei)

(flat)

tratifie are

classifie "y

the

morpholoy

of the cells in

their superficial

layer only


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Types of simple epithelium

1- simple s6uamous

%- simple cu"oial

*- simple columnar - ciliate

- non ciliate

4- pseuostratifie columnar


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/seuostratifie epithelium

/ t tifi


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/seuostratifie

epithelium


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Types of stratifie epithelium

1- stratifie s6uamous

- 'eratini7e

- non 'eratini7e %- stratifie cu"oial

*- stratifie columnar

4- transitional epithelium


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'eratini7e

stratifie s6uamous

8 ' ti i


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8on-'eratini7e

stratifie

s6uamous


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eratini7e stratifie s6uamous

epithelium

nonkeratinized


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Transitional epithelium


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Transitional epithelium


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tratifie transitional epithelium


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/olarity an cell-surface

speciali7ations

9ost epithelial cells ha!e apical omain an"asolateral omain.

The apical omain represents the free surface of

the epithelial cells (part of the cell that faces thelumen).

The "asolateral omain inclues the "asal anlateral aspects of the cell mem"rane.

The apical an the "asolateral omains areseparate from each other "y tiht :unctions thatencircle the apical aspect of the cell.


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9oifications that are necessary for the

apical omain to carry out its functions.

1- Microvilli; are small finer li'ecytoplasmic pro:ections. (E9) (1-%


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9icro!illi


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9icro!illi


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9icro!illi


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!"lycocaly#represents car"ohyrate resiuesattache to the transmem"rane proteins of theplasmalemma (i.e. ?lycoproteins). They functionin protection an cell reconition.

$!Steriociliaare lon nonmotile micro!illi founonly in epiiymis an on the sensory hair cellsof the cochlea (inner ear). 2n epiiymis theyfunction in increasin the surface area anfacilitatin the mo!ement of molecules into anout of the cellsA in the hair cells they function insinal eneration.


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%! &iliaare lon (B-1=


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&ilia


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asal "oy; structurally similar to a

centriole anchors the tu"ules in

the cell

&ilia movement'

!Sliding the microtubules

doublets past each other

!his action needs *+

&omposition of cilia and flagella

(C+%)


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&ilia


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,! -lagella.

permato7oa one

per cell an similar in

structure to cilia.

&ilia

-lagellum.


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Lateral mem"rane speciali7ation

Lateral mem"rane speciali7ations re!eal thepresence of :unctional comple$es.

unctional comple$es may "e classifie into *

types .!/mpermeable 0unctions; function in :oinincells to form an impermea"le "arrier pre!entinmaterial from ta'in an intercellular route in

passin across the epithelial sheath. E.. tight0unction (1onulae 2ccludentes)


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ight 0unctions

Tiht :unction form a "elt li'e:unction that encircles theentire circumference of thecell.

ight 0unctionsfunction in twoways

1- pre!ent the mo!ement ofmem"rane proteins from theapical omain to the"asolateral omain

%- fuse plasma mem"ranes ofa:acent cells to pre!ent water

solu"le molecules frompassin "etween cells in eitherirection.


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ight 0unctions


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! *nchoring or adhering 0unctions;function in maintainin cell-to-cell or cell to"asal lamina aherence. E..

esmosomes an hemi esmosomes. $! &ommunicating 0unctions; function in

permittin mo!ement of ions or sinalinmolecules "etween cells thus couplina:acent cells "oth electrically anmeta"olically. E.. ?ap :unctions.


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Desmosomes

0re wel li'e :unctions alon thelateral cell mem"ranes that help toresist shearin forces.

Dis' shape attachment pla6uesare locate opposite each other onthe cytoplasmic aspects of the

plasma mem"ranes of a:acentepithelial cells. Each pla6ue is compose of a

series of attachment proteins(esmopla'ins an pa'olo"ins)

2ntermeiate filaments ofcyto'eratin are o"ser!e to insert

into this pla6ue.ee fiure;

! 3esmogleinre6uires

a+%

! /ntegrins are receptor sites for

the e$tracelular macromolecules

laminin an collaen type 23


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Desmosomes


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3esmosome

Microvilli and cillia and steriocellia

4eretinized

4+5 tissue types and epithelial tissue.ppt

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