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Histology
1. Characteristics of epithelial tissue (Fares and Jamal)
Epitehelium is tissue organized as attached sheets of cells which line orcover and form tubular structures within organs.Location Covers all body surfaces/lines cavitary organs and forms exocrine& endocrine glands.hey originate in all ! embryonic layers" Endoderm #igestive$ respiratory$thyroid %esoderm Endothelium$ %esothelium
Ectoderm Epidermis$ adenohypophysisComposed of compact mass of specialized cells EC matrix contains smallamount of cells with a highly organized basement membrane.
Characteristics' various cell shapes and functions$ avascular$ (nnervated$renewable$ and can undergo metaplasia.)hapes" *latted +s,uamous-$ cuboidal and columnar*unctions" protection$ absorption$ transport of material at surface & gasexchange$ secretion$ excretion and contraction.
. Characteristics of epithelial tissue. +ohn-
Location0covers all body surface/lines cavitary organs
0forms exo' and endocrine glands.
Origin ' in all ! embryonic layers0endoderm" digestive$ respiratory epithelium$ thyroid0mesoderm" endothelium$ mesothelium0ectoderm" epidermis$ adenohypophysis
Composed of0Cells" compact mass of specialized cells0Extracellular matrix"0small amount
0highly organized ' basement membrane
Characteristics:01arious cell shapes and functions
Cell shapes" 2attened$ cuboidal$ columnar
he nuclear form often corresponds to the cell shape
0 3vascular
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0 (nnervation
free nerve endings un'myelinated axons
depends on location of the epithelium and its exposure to stimuli
0 4enewal
Epithelia continuously renew their cell population
#i5erent rates" fastest small intestine$ slowest' s6in0 %etaplasia7transformation into another type of mature epithelium$ in pathologicalcircumstances
issue has the ability to transform into a di5erent tissue if something
goes wrong. Can be reversed if the stimulus goes away.
E.g.
2. Polarity of epithelial tissue and epithelial cell. Differences between apical andlatero-basal domains of epithelial cells (Fares and Jamal)
8olarity is due to organelle distribution and membrane protein distribution+membrane domain-3pical domain" 8roteins enzymes$ transporters$ channels Lipids Cholesterol$ sphingomyelin9aso'lateral domain" 8roteins :a;/
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=. 8olarity of epithelial tissue and epithelial cell. #i5erences betweenapical and latero'basal domains of epithelial cells +ohn-
Cells will always have an apical pole$ a lateral pole and a basal pole
he free or apical domainis always directed toward the exterior
surface or the lumen of an enclosed cavity or tube. he lateral domaincommunicates with ad>acent cells and is
characterized by specialized attachment areas.
he basal domainrests on the basal lamina anchoring the cell tounderlying connective tissue.
hey are ?polarized@"
#epending on the di5erent tissue types$ di5erent things go on at each
pole polarized distribution of organelles and membrane proteins,
depending on cell function
Organelle polarity in cells:Type of cell 3pical pole 9aso'lateral pole3bsorptive cell %itochondria
3ctive absorptionre,uires 38
)ecretory cell Aolgi apparatus 7Bsecrete vesicles at theapical pole
4E4 located here+protein synthesis:ucles located below
Polarity of membrane proteins and lipids membrane domains:
Component 3pical domain 9aso'lateral domain8roteins 0Enzymes
0ransporters0Channels
0:a;/
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04eceptors03dhesion proteins
Lipids 0Cholesterol0)phingomyelin
08hosphatidylcholine08hosphatidylinositole
. !peciali"ations of the apical domain (cilia# micro$illi# stereocilia)%
structure# ultra structure# locali"ation and functions (Fares and Jamal)Cilia )eperated into motile and primary cilia- ' 8rimary cilia found in nearly every cell of the body$ movessubstances using passive 2ow of 2uid$ also can function as sensory antennae ' %otile cilia found in epithelia which are involved in transporting$uses active movement ' 9oth types of cilia possess axoneme$ basal bodies and intra 2agellartransport system)tereocilia 3ctin laments bundle anchored into a terminal web ' Located in male reproductive system +absorptive function- andinner ear$ where it *unctions as mechanoreceptors%icrovilli 3lso actin laments bundled into terminal web ' 8resent in many epithelial cells
' increases absorptive surface of cells ' 1isible in L% as striated/brush border
. )pecializations of the apical domain +cilia$ microvilli$ stereocilia-")tructure$ ultra structure$ localization and functions
(n many epithelial cells$ the apical domain exhibits special structural surfacemodications to carry out specic functions +shown in table below-
!icro"illi and stereocilia"
Types ofcilia:
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&. !peciali"ations of the latero-basal domain (Fares and Jamal)*uc6 this bullshit ,uestion.
D. )pecializations of the latero'basal domain +ohn-#omain )pecializationsLateral Celltocell complexes:
#$ ight >unctions%$ 3nchoring >unctions
wo types +on lateral pole-
zonula adherens
macula adherens or desmosome$
&$ Aap >unctions
9asal Celltoextracellular matrix 'unctionsanchor the cellto the extracellular matrix
. *ocal adhesions=. emidesmosomes
. ight unctions"
(mpermeable and allow epithelial cells to function as a barrier.
Limit the mo"ement of (ater and other moleculesthrough theintercellular space 7B maintain physicochemical separation of tissuecompartments.
Pre"ent the migration of lipids and specialized membraneproteinsbetween the apical and lateral surfaces$ 7B maintain theintegrity of these two domains
=. 3nchoring unctions"8rovide lateral adhesions between epithelial cells$ using proteins that lin6into the cytos6eleton of ad>acent cells.) zonula adherens +pl.$zonulae adherentes-$ which interacts with the
networ6 of actin laments inside the cell and) macula adherens +pl.$ maculae adherentes- or desmosome$ whichinteracts with intermediate laments
!. Aap >unctions8ermit the direct passage of signalling molecules from one cell to another.
F subunits +connexions- 7B connexons 7B gap >unction
3llows cells to function together
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+9asal pole-. *ocal adhesions
3nchors actin of the cytos6eleton in the cell to the extracellular matrix
=. emidesmosomes3nchors intermediate laments of the cytos6eleton to the extracellularmatrix
'. amina basalis and basement membrane
9asal lamina" )heet of EC material between epithelial and connective tissue. Gnly visible in E% =H'HHnm thic6 Consists of lamina densa+brilar networ6- and lamina lucida
Composed of molecules secreted by epithelial cells" type D collagen$ A8@sand 8A@s9asement membrane is a thic6 structure formed by basal lamina andreticular lamina.(t anchors down the epithelium to the loose connective tissue underneath9oth basal lamina and basement membrane are specializations of thebasolateral pole
. Classification of co$erin* epithelia
9ased on number of cell layers"' )imple' )tratied
9ased on cell shape"' ),uamous +2attened-' Cuboidal' Columnar
ypes include" ' )imple/stratied s,uamous/cuboidal/columnar ' 8seudostratied ' ransitional/urothelium
I
+. !imple epithelia% characteristics# locations# functions
)imple s,uamous" located in endothelium$ mesothelium$ bowmans capsuleetc. *unctions include ltration$ di5usion$ osmosis$ secretion+serosa-)imple cuboidal" Located in 6idney tubules$ excretory ducts of excretoryglands and covering
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Epithelium of ovary *unctions are secretion and absorption)imple columnar" Located in digestive tract$ fallopian tubes$ excretory ductsof salivary glands as apical surface specializations +cilia and microvilli-$ for
absorption$secretion
,. Pseudostatified epithelium% characteristics# locations# functions
Located in respiratory epithelium and male reproductive system*unctions include secretion +goblet cells-$ clearance +ciliated cells- andabsorption +stereocilia-(t has apical surface specializations" cilia and stereociliaConstists of single layer of cells with nuclei similar to stratied epithelia(t gives the impression of more than one layer of cells but it@s a single layer
resting on basal lamina. his is because the nuclei are disposed at di5erentlevels.
. !tratified suamous /eratini"ed epithelium% characteristics# location# functions#
)ame as stratied s,uamous +layer of 2at cells- but with dead 6eratinizedcells at surface*orms the epidermis of s6in8rotects underlying tissues in areas sub>ect to abrasion
10. !tratified suamous non /eratini"ed epithelium% characteristics# location#functions#
)ame as stratied s,uamous +layers of 2at cells- but has living$ nucleatedcells at surfaceLocated in digestive tract from mouth to esophagus$ and also in the vaginaand anterior cornea8rotects areas sub>ect to abrasion
11. !tratified cuboidal and columnar epithelia% characteristics# locations# functions
)tratied cuboidal" ' located in sweat glands and excretory duct' functions are protection and secretion' consists of layers of cuboidal cells
)tratied columnar" ' located in ocular con>unctiva and large ducts of salivaryglands
' *unctions are protection and absorption' Layers of columnar cells
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12. ransitional epithelium% characteristics# location# functions
Consists of basal cells$ rac6et shaped cells and umbrella'li6e cellsLocated in urinary excretory tract
*unctions" stretches allows organs to distend 8rotective osmotic barrier
1. ndocrine *landular epithelium% classification
Alandular epithelium is one or more epithelial cells highly specialized for
secretion.)ecretory process has D phases" 3ssimilation$ synthesis$ storage andsecretion.Endocrine glands have no connection with the surface completelysurrounded by conn tissueEliminates secretory product directly into blood streamhey can be classied based on"' Cell grouping cords$ follicles$ islets$ isolated cells' Chemical structure of secretory product small polypeptides$ cholesterol' %oment of release of secretory product immediate release$ after storage-4ange of action of secretory product autocrine +on itself-
' 8aracrine +small range neighbouring cells-' Endocrine +at distance-
1&. 3ocrine *landular epithelium% classification4 e3amples
Exocrine glands are in contact with free surface of epithelium by an excretoryduct.Eliminates product through a ductClassication"' 9y structure" )imple ubular Lieber6uhn Aland
' Coiled tubular' 9ranched tubular' acinar' 9ranched acinar
' 9y chemical composition of secretory product" %ucous gland +product richin A8@s$ viscous- )erous gland +proteinsecreting cell-
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%ixed gland' 9y secretion mechanism merocrine +exocytosis of stored granules-
' 3pocrine +secretion of both product and apicalcytoplasm-
' olocrine +destruction of entire cell during secretion-
1'. Cells speciali"ed for protein synthesis (serous cells)
ype of exocrine cell8olarity" basal pole rich in 4E4 Aolgi above round nucleus in central area 3pical pole with zymogen granules)ecretion" enzymes +pancreas$ salivary glands- ormones +parathyroid ' 8-
1. Cells speciali"ed for *lycoprotein synthesis (mucous cells)
' Exocrine Cells
' 8olarity" 9asal 8ole" :ucleus$ Grganelles3pical 8ole" )ecretory Aranules
' Location" %ucus'secreting cells" Aoblet Cells' intestinal ; respiratoryepithelium
%ucous 3cini' salivary glandsAastric Epithelium
ormone'secreting cells" 3denohyphysis
1+. Cells speciali"ed for lipid synthesis
' Location" Exocrine Cells ' )ebaceous gland
Endocrine Cells Leydig Cells' estis *ollicular Cells Gvary 3drenal Cortex Cells
1,. Cells speciali"ed for amines and small peptides synthesis
7 #igestive tract entero'endocrine cells
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' )omatostatin +# Cells-' 1(8 +# Cells-' )erotonin +EC Cells-' Colecistochinin +( Cells-' A(8 +< Cells-
' %otilin +%o Cells-' :eorotensin +: Cells-' )ecretin +) Cells-
1. Cells speciali"ed for ions transport (serous cells)
4eabsorption" ' Jniferous tubules' Excretory ducts$ salivary glands' #igestive tract
)ecretion" ' Endothelial Cells' Ciliary processes
' Ependymal cells Choroid plexus
20. 5yoepithelial cell
Location )urrounding secretory portion of" )alivary glands$ lacrimal glands$sweat glands ; mammary glands
*eatures" ' Cyto6eratin laments' epithelial tissue' Contractile laments muscle tissue
' A38 >unctions' synchronizing' #esmosomes with epithelial cells' emidesmosomes with basement membrane
21. 5erocrine# apocrine# holocrine mechanisms of secretion4 e3amples
!erocrine secretion" Exocytosis of stored secretory granules
*pocrine secretion:secretion of product along with apical cytoplasm
Holocrine secretion:destruction of entire cell during secretion
CG::EC(1E ())JE22. Definition# basic structure and functions of connecti$e tissues.
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#enition" tissue that connects$ supports$ binds or separates other tissuesor organs typically having relatively few cells embedded in an amorphousmatrix often with collagen or other bers.
*unctions" ')tructural support +capsules$ bone$ cartilage-
' :utrition' #efense +nonspecic ; immune-' Cell growth ; #i5erentiation' Cell migration' (nsulation
Characteristics"' common embryological origin 7 mesoderm' (nnervated ; 1ascularized +direct blood supply-K cartilage is only exception with no capillary beds K'EC matrix ' ground substance +gelatinous glycoproteins-
' structural bers +brous proteins eg" collagen$ elastin$reticulin-
ypes"'Connective issue 8roper ' loose
' dense +brous- irregular' dense +brous- regular
' )pecialized Connective issue" 'adipose tissue' reticular' elastic' cartilage +hyaline$ elastic$ brocartillage-
' bone' blood
2. !tructure and ultrastructure of connecti$e tissue fibers% colla*en#
elastic# reticular.
*ibers ' proteins that are embedded in the ground substance ' provide structural support$ adhesion$ connect cells
' Collagen ' tough provides high tensile strength
' also called white bers ' highly polymerized$ gigantic molecules ' tough$ moderate 2exibility ' bone$ cartilage$ tendons ligaments
'Elastic bers 7 Elastin ' branched smaller$ thinner bers thancollagen
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' very 2exible ; elastic but also strong' can be stretched to HM of its original length' 3
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' *ibril associated collagen" ypes (S ; S((' :etwor6'forming collagen" ype (1' 3nchoring collagen" ype 1((
2. 6round substance% molecular composition and functions
' participate sto binding cells to bers' colorless ; transparent in usual stains' %ay be solid$ 2uid or gel'Components" ' Cell 3dhesion 8roteins
- *ibronectin' binds cells$ collagen ; A3A=- Laminin mediates attachment of epithelial cells to
basal laminae
' 8roteioglycans large polysaccharide molecules bound toprotein core
' Alycosaminoglycans +A3As- linear polysaccharidescomposed of repetitive disaccharide units$ attached toproteoglycans
2+. Connecti$e tissue cells% classification
8roper to connective tissue +*ixed Cells-' *ibroblast' brocyte +condro' $ osteo' -' %yobroblast
' 3dipocyte +uni' $ multiocular-' 4eticular
%igrated' granulocytes' 9 ; lymphocytes' %acrophages' %ast cells' %elanocytes' 8lasma cell
Cells that produce/degrade the EC matrix' broblasts$ osteoblasts$ condroblasts$ macrophages
%etabolic Cells' adipocytes
#efense +)pecic/:on')pecic-
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' lymphocytes$ macrophages$ neutrophils$ mast cells$ plasma cells
2,. Fibroblast-fibrocyte% structure# ultrastructure# functions
*ibroblast' %ost fre,uent cell
' L! Elongated cells$ =HTm$ branched processes$ basophilic cytoplasm$oval$ euchromatic nucleus$ or = nucleoli' TE! abundant 4E4 ; prominent Aolgi apparatus
8roduce"' Elements of EC %atrix" 8rocollagen$ proelastin$ brilin$ A3A$ 8roteoglycans; Alycoproteins' Enzymes" %atrix metalloproteinases ; Collagenase ; Elastase
' Arowth *actors
8roperties"' ability to switch its phenotype" *ibroblast *ibrocyte
' can change shape' mobile' induces di5erentiation of surrounding cells
+%yobroblasts 7 *ibroblasts that contain actin-
2. 7nilocular8white adipocyte% structure# ultrastructure# functions
' L!' round +when isolated- G4 polygonal in groups ' one large lipid droplet +inclusion-
' 3 thin rim of cytoplasm at the periphery that contains a 2attened$heterochromatic nucleus +Usignet ringV-
' TE! )mall Aolgi complex$ 4E4$ mitochondria ; microlaments
*unctions" secrete adipo6ines$ resistin$ adiponectin$ leptin ; apelin.
0. 5ultilocular8brown adipocyte% structure# ultrastructure# functions
' smaller than white adipocytes' %ostly found before birth and in neonates
L!' many small lipid droplets in cytoplasm foamy loo6
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' round central nucleus TE! many mitochondira +high concentration of cytochromes in themitochondria is responsible for brown color of the aggregates of multiocularadipcytes brown color also due tohigh vascularization ! capilaries for each
brown adipocyte-
1. 9eticular cell% structure# ultrastructure# functions
*unctions' 8roduce reticular bers$ which form the ne structural networ6 of organssuch as the lymph nodes$ spleen and bone marrow.' )ynthesizes type ((( Collagen' hey also direct 9 cellsand cellsto specic regions within the lymphatictissue.
L! )tar'shaped cells with long and thin processes that establish anchoring>unctions with neighboring cells round$ central$ pale nucleus.
K)hould not be confused with the reticulocyte$ an immature erythrocyte
2. 5acropha*e% structure# ultrastructure# functions
#erived from peripheral blood monocytes$ (nvolved in phagocytosis andin2ammatory response' 3 family of cells with various shapes$ localizations and names"' istiocytes" connective tissue'
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TE!' numerous lysosomes$ phagosomes and pseudopodia$ abundant 4E4$)E4$ mitochondria and Aolgi complex.
*unctions" %ain function" phagocytosis
' riggered by a specic interaction between membrane receptors andligands.
Conse,uences"Cell movement towards target particle8seudopodia formation engulfment4espiratory burst)ecretion" cyto6ines$ interferon$ complement & coagulation factors8roduction of matrix metalloproteinases
&&$ !ast cell: structure, ultrastructure, functions
)tructure
Large$ Gval cell$ =H'!H mm Cytoplasm has numerous basophilic$ metachromatic
granules
Jltrastructure
. %any granules
=. extensive Aolgi complex
!. cisternae of 4E4
D. free ribosomes$ mitochondria and numerous microvilli and folds.
. 4ich in istamine & eparin
*unctions
3 mobile macrophage cell of the connective tissue$ able to perform phagocytosis$
plays a ma>or immune role in allergies$ also involved in wound healing and defense
against pathogens.
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+otes
1ery similar to basophil +both in function and appearance-$ it is located in most of
the loose connective tissue along blood vessels.
&$ Plasma cell: structure, ultrastructure, functions
)tructure
8ear/Gvoid shaped cells$ basophilic cytoplasm +due to abundant 4E4- with a
perinuclear pale area +Aolgi apparatus-$ can contain acidophilic 4ussel bodies
+secretory granules-
Eccentric and visible :ucleus$ with hetero and euchromatin in a Xcloc6faceX pattern
meaning theyYre assembled in a circular manner around the periphery of the
nucleus +much li6e numbers on the cloc6-
Jltrastructure
Extensive Aolgi complex$ abundant 4E4$ secretory granules +4ussel bodies-$ free
ribosomes & methachondria.
*unctions
%ainly secrete immunoglobulins +antibodies-" (g%$ (gA$ (g3$ (gE$ they originate in 9
lymphocytes that are terminally di5erentiated as a result of a response to anantigen challenge.
&-$ Classi.cation of connecti"e tissues
The classi.cation is based on the composition and organization of the
componants and its functions/
#$ Embryonic connecti"e tissue
%esenchye
%ucous connective tissue
%$ *dult connecti"e tissue
Loose connective tissue
#ense +brous- connective tissue
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#ense regular connective tissue
#ense irregular connective tissue
4eticular connective tissue
Elastic connective tissue
&$ 0pecialized connecti"e tissue
3dipose tissue
Cartilage
9one
ematopoietic +bone marrow-
9lood
&1$ Loose connecti"e tissue: structure, localization
)tructure
Comprised of all the main componants of a connective tissue in e2ual
proportions, "ery di"erse in types of cells/ most numerous being
.broblasts 3 macrophages
3bundant ground substance$ collagen$ elastic and reticular bers$ very 2exible andvery well vascularized$ and relativly delicate.
Localization
)upports epithelial tissues
Ensheathes the lymphatic and blood vessels
8apillary layer of the dermis
he serosal linings of peritoneal and pleaural cavities
Alands and mucous membranes
&4$ 5ense irregular connecti"e tissue: structure, localization
)tructure
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*ew cells +compared to loose C-$ mainly brocytes +occasional mast cells &
macrophages-
Clear predominance of collagen bers
*ew ground substance
Less 2exible thus more resistant to stress
The collagen .bers are bundled 67TH +O 5E87+7TE O97E+T*T7O+ hence
labelled irregular;
hree deminsional networ6 B 4esistant to stress from all angles
Localization
Capsules of the parenchimatose organs
#ermis
)ubmucosa of the digestive tract
8eriosteum
8erichondrium
&
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)econdary 9undles of endotenonium loose connective tissue with blood
vessels and nerves ' Peritenonium
External sheath of dense connective tissue ' epitenonium
Localization
9etween striated muscle and bone
&>$ *poneuroses: structure, localization
)tructure
inextensible structure that attaches striated muscle to bone +or other muscles-
hic6 and predominant collagen bers
%ultiple layers"
8arallel in the same layer
perpendicular on the collagen bers from the layers above and beneath
+textile aspect-
*ibrocytes ' *lattened$ narrow shaped
+ote the fastest and easiest (ay to identify on a slide is to pay
attention to the textile orginization of the collagen .bers
Localization
9etween muscle and bones +and sometimes between muscles and other muscles or
structures$ basically attaches the epiphysis of the bone to other structures-
?$ 9eticular connecti"e tissue: structure, localization
)tructure
)pecialized loose connective tissue$ double mesh(or=" 9eticular cells 3 a
net(or= of branched reticular .bers, reticular bers are enveloped by the
cytoplasm of reticular cells the bers however are ES43CELLJL34 being
seperated from the cytoplasm by the cell membrane
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Localization
*ramewor6 of the bone marrow and lymphoid tissue +lymph nodes$ spleen-$
supports the soft organs in the periphery.
#$ Elastic tissue: structure, localization
)tructure
Predominance of parallel thic= elastic .bers +remember orcein & furschin
stain- and bet(een them rare collagen .bers and @attened .broblasts
Localization
yellow ligaments of the spinal chord
)uspensory ligaments of the penis
*unction ' 8rovide elasticity
%$ !ucous tissue: structure, localization
*n embryonic connecti"e tissue
)tructure
Aelatin'li6e extracellular matrix +very loose-
*bundanceof amorphous ground substance +also 6now there as
whartonYs >elly-
Thin collagen .bers
0pindleshaped cells +mesenchymal cells-
Localization
Ambilical chord
&$ 6hite adipose tissue: structure, localization
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)tructure
8at cells 3 thin layers of loose irregularconnecti"e tissue
Jnilocular +have only one cavity-/white adipocytes '
round +when isolated- or polygonal in groups
cytoplasm ' a thin rim at the periphery Gne large lipid droplet +inclusion-
nucleus ' 2attened$ heterochromatic Xsignet ringV and compressed onto the cell
membrane by the lipid droplet.
Zhite to dar6 yellow due to carotenoids +organic pigments-
)mall amounts of collagen$ elastic bers and ground substance
Localization
hroughout the human body$ distribution is regulated endocrinologically according
to gender and age.
$ 6hite adipose tissue: function
%ainly store energy$ insulate and cushioning of vital organs.
Energy storage '
3dipocytes are specialized for synthesis$ storage$ and mobilization of neutral fats+triglycerides-. ormones$ such as insulin$ and the sympathetic nervous system$
which innervates adipose tissue$ control these activities. hese fats are stored in
nonmembrane'bound lipid droplets. Zhen fats are needed to provide fuel for cells
in other tissues$ adipocytes release them as fatty acids into circulation. #ietary
lipids from the intestine also circulate in blood as water'soluble lipoproteins called
chylomicrons. ogether with very'low'density lipoproteins +1L#Ls- from the liver$
they reach the adipocyte surface via capillaries. Lipoprotein lipase$ an enzyme
produced by adipocytes$ releases fatty acids and monoglycerides from chylomicrons
and 1L#Ls that are then moved to the adipocyte cytoplasm. 4e'esterication into
triglycerides occurs in the smooth endoplasmic reticulum$ followed by storage in
lipid droplets. )ome fatty acids are also produced from glycogen in adipocytes.
)cattered mitochondria$ a small Aolgi complex$ and cytos6eletal laments are other
organelles in the cytoplasm. 3dipocytes also secrete steroid hormones$ cyto6ines$
and leptin$ a peptide hormone$ which functions in appetite regulation by acting on
the hypothalamus.
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-$ Bro(n adipose tissue: structure, localization
)tructure
8redominance of brown adipocytes
Zell vascularized
Bro(n adipocyte
%ultilocular$ polygonal and smaller comapred to white adipocytes
)pherical$ central nucleus
Cytoblasm"
Areat nuber of lipid dropletsthat "ary in size
+umerous mitochondria with abundant long cristae
Epithelial'li6e arrangment where the cells are closely pac6ed in masses and
assosiated with blood capillaries.
)ubdevided by connective tissie into lobules$ better delineated +compared to
unilocular adipose tissue-
Cells recie"e direct sympathetic inner"ation
Localization
Large amounts in newborn
)carce at the adult
(n the cervical and mediastinum region +except perirenal & periaortic-
1$ Bro(n adipose tissue: function
hermogenetic activity
eat production$ and the recruitment process in the tissue +that results in a higher
thermogenic capacity- are under the control of norepinephrine released from
sympathetic nerves. (n thermoregulatory thermogenesis$ brown adipose tissue is
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essential for classical nonshivering thermogenesis +this phenomenon does not exist
in the absence of functional brown adipose tissue-$ as well as for the cold
acclimation'recruited norepinephrine'induced thermogenesis. eat production from
brown adipose tissue is activated whenever the organism is in need of extra heat$
e.g.$ postnatally$ during entry into a febrile state$ and during arousal from
hibernation$ and the rate of thermogenesis is centrally controlled via a pathwayinitiated in the hypothalamus. *eeding as such also results in activation of brown
adipose tissue a series of diets$ apparently all characterized by being low in
protein$ result in a leptin'dependent recruitment of the tissue this
metaboloregulatory thermogenesis is also under hypothalamic control. Zhen the
tissue is active$ high amounts of lipids and glucose are combusted in the tissue. he
development of brown adipose tissue with its characteristic protein$ uncoupling
protein' +JC8-$ was probably determinative for the evolutionary success of
mammals$ as its thermogenesis enhances neonatal survival and allows for active
life even in cold surroundings.
4$ Hyaline Cartilage: structure, localization
)tructure
CELLAL*9 CO!P*9T!E+T:
0 Chondroblasts
0 Chondrocyte
*ound in matrix cavities 'lacunae
*rranged in isogenous groups clusters or columns;
0 8erichondrium cells
!*T97
0 erritorial matrix
0 interterritorial matrix
Components"
. *ibers" collagen ((.
=. Around substance
Localization
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(n the fetus '
8orming the s=eleton
(n adults '
+ose, Larynx, Trachea, Bronchus, Dentral end of ribs, *rticular surface ofsome bones 3 in gro(th cartilage of long bones
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*ppearance under microscope:
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H. Chondroblast$ and chondrocyte" structure$ ultrastructure$ localization
5e.nition:
Chondroblast" (mmature chondrocyte
' #ivide
' )hape" elliptical long axis parallel to the surface of the cartilage
' 3lso secretes antiangiogenesis factor a substance that prevents blood vessel
growth-
3nti7 against$ angio7 vessel$ genesis 7 production 7B antiangiogenesis.
Chondrocyte" %ature cell of the cartilage
' #o not divide
' )hape" round
Chondrocytes are distributed either singularly or in clusters called isogenous
groups
Zhen the chondrocytes are present in isogenous groups$ they represent cells that
have recently divided. 3s the newly divided chondrocytes produce the matrix
material that surrounds them$ they are dispersed
Cell type 0tructure Altrastructure LocalizationChondroblast +uclei:
4ound andbasophilicEuchromatic+active-'= nucleiCytoplasm:9asophilic
uxtanuclear pale
4E4$ Aolgi$
%itochondria$glycogen$ lipiddroplets allpresent%any shortcytoplasmicpro>ections
Cells are
isolatedlocated attheperipheryunder theperichondrium
K*ound in lacunae
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region 3*E4 theysecrete matrixtherefore mostperipheralchondroblastsaren@t in lacunae
Chondrocyte +uclei:4ound andbasophilicCytoplasm:3cidophilic
*ew organelles(ncreased"
Alycogen
Lipid
droplets#ecreased"
)ynthesis
Cells form
groupscentrally.
KCompletely lllacunae
9oth secrete all components of the matrix +bres and ground substance-
. Aeneral structure of osseous tissue.
5e.nition:
Bone is a specialized form of connective tissue that$ li6e other connective tissues$
consists of"
Cells +osteoblasts and osteocytes-
Extracellular matrix-.
Grganic matter +osteoid-" amorphous ground substance and collagen bres
(norganic matter +minerals-
he feature that distinguishes bone from other connective tissues is the
mineralization of its matrix$ which produces an extremely hard tissue capable of
providing support andprotection.
he mineral is calcium phosphate in the form of hydroxyapatite crystals
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*orms of bone"
. %icroscopic
*orm of bone Aeneral description8rimary +immature$ woven- 7rregulararray of collagen bres
igher proportion of osteocytesLower mineral content
)econdary +mature$ lamellar- 9egular bands of collagen bresarranged in sheets +lamellae-
=. %acrocopic
*orm of bone #escriptionCompact +#ense- bone C.9 3 compact$ dense layer forming
the outside of the bone.
Cancellous +spongy- bone ).9 a sponge'li6e meshwor6 consistingof trabeculae +thin$anastomosing spicules of bonetissue- forming the interior of thebone
he spaces within the meshwor6are continuous and$ in a livingbone$ are occupied by marrow andblood vessels
=. Gsteoblast$ osteocyte$ osteoclast" structure$ ultrastructure$ functions
9one cell )tructure Jltrastructure
Localization
*unctions
Gsteoblast 0hape" columnar$cuboidal +matrixsynthesis-$ 2attened+inactive-+ucleus:8ale staining%ultipleCytoplasm:9asophilicCytoplasmicprocesses7Bcontact withneighbouring cells
4E4$ Aolgi$%itochondria
Liningbone+endosteum$periosteum$trabeculae$metaphysis- (.esites ofbonewhereremodelling is notoccurring
:G celldivision)ynthesizethe organiccomponents of matrix
Gsteocyte 0hape: 4educed Located Gsteocytes
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*lattenedElongated+ucleus:*lattenedCondensed chromatinCytoplasm:
Less basophilic andmore acidophilicLO+, thincytoplasmicprocessesFGentermatrix canaliculi 7Bad>acent cells ma6econtact via gap
>unctions
organelles betweenlayers ofosteon+ concentricarrangement of
bonetissuearoundbloodvessels-andoccupylacunae
cansynthesizenew matrix
Gsteoclast Large%ulti'nucleatedCytoplasm:acidophilic
:umerouslysosomes
*ound atsiteswherebone isremoved
4esponsiblefor bone
resorption
!. (ntramembranous ossication
+di5erence with endochodral ossication-
http"//answers.yahoo.com/,uestion/index[,id7=HHQ=H=!=D33EGsLJ
5e.nition: (n intramembranous ossication bone is formed by di5erentiation of
mesenchymal cellsinto osteoblasts.
*or 2at bones
)ome of the pale'staining$ elongated mesenchymal cells within the
mesenchyme migrate and aggregate in specic areas$ the sites where bone is
destined to form. his condensation of cells (ithin the mesenchymal
tissueinitiates the process of intramembranous ossication.
0tages:
. Aroup of mesenchymal cells di5erentiate \osteoblasts secrete matrix which
then becomes mineralized=. \(slands of developing bone +)8(CJLE)-!. *usion of )picules \ 439ECJL3E in C3:CELLGJ) +spongy- boneD. \ Arowth and fusion of trabeculae \ CG%83C bone
D. Endochondral bone formation
5e.nition: %esenchymal cells di5erentiate into chondroblasts that$ in turn$
produce cartilage matrix.
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*or long bones
7nitially, a hyaline cartilage model (ith the general shape of the
bone is formed$
8rocess begins with the proliferation and aggregation of mesenchymal cells
at the site of the future bone
)tages"
he process begins with the formation of a cartilage model
#- 3 periosteal +perichondrial- collar of bone forms around the diaphysis +shaft- of
the cartilage model
+%- then$ the cartilaginous matrix in the shaft begins to calcify
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+&-. 9lood vessels and connective tissue cells then erode and invade the calcied
cartilage
+-$ creating a primitive marrow cavity in which remnant spicules of calcied
cartilage remain at the two ends of the cavity. 3s a primary center of ossication
develops$ the endochondral bone is formed on spicules of calcied cartilage. hebone at the ends of the developing marrow cavity constitutes the metaphysis.
8eriosteal bone continues to form
+-- the periosteal bone is formed as the result of intramembranous ossication.
9lood vessels and perivascular cells invade the proximal epiphyseal cartilage
+1-$ and a secondary center of ossication is establishedin the proximal epiphysis
+4-. 3 similar epiphyseal +secondary- ossication center forms at the distal end of
the bone
+-$ and nally$ with cessation of growth$ the proximal epiphyseal cartilage
disappears
+#?-. he metaphysis then becomes continuous with the epiphysis. Epiphyseal lines
remain where the epiphyseal plate last existed.
. Composition of plasma
F. Erythrocytes
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5e.nition:a6a red blood cells
Pathology:
cytopenia 7 lower than normal +associated with anemia-$
cytosis 7 higher than normal +e.g.polycythemia vera-
0ize:
' ]P. ^m diameter fresh
' P.= ' P.D in stained smears
'H$Q =$F ^m thic6
Constant diameter allows 49Cs to be used as a
scale to compare with other cells"
0macrocytes B R ^m$
0microcytes _ F ^m
0anisocytosis 7 variation in size
)tructure Jltrastructure *unction9iconcave disc
folding increases
surface area +!HMmore surface area-
composition of
plasma membranegives 2exibility+s,ueeze throughcapillaries-
RPM hemoglobin
:o nucleus:o centrioles
:o organelles:o mitochondria
no cell division +as
a result of no
centrioles$ nucleior organelles- no mitochondria
means they cangenerate 38anaerobically 7Bpreventsconsumption of theG=that theytransport
ransport G=
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P. #i5erential count of blood leu6ocytes
*im: helps to indicate what type of disease may be present in a patient
!ethod:
. Gbtain sample of venous blood from patient=. 8lace one drop of blood on to slide!. 8repare a smearD. Jsing light microscopy$ count HH blood cells$ noting each leu6ocyte type and
their fre,uency.
+ormal 2uantities in blood:
:eutrophils 7 DQ'FFM
Eosinophils 7 'DM
9asophils" H'H.M
%onocytes 7 QM
Lymphocytes 7 ='=PM
Pathological results and indications:
(ncrease in"
:eutrophils" acute bacterial in2ammation
Eosinophils" allergic reaction$ parasitic infection$ chronic in2ammation
9asophils" allergic reaction therefore basophils release histamine
Lymphocytes" in viral infections and tumour cells
Q. :eutrophil" structure$ ultrastructure and functions
5e.nition:
)tructure Jltrastructure *unctionsLarger than 49C
#iameter 7 H'=
micrometresPolymorphonuclear:
:ucleus has
multiple lobes
+ucleus:as heterochromatin atthe periphery andeuchromatin morecentrally0mall golgi apparatus
:eutrophils are activephagocytes that utilize avariety ofsurface receptors torecognize bacteria andother infectious
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connected bychromatin
Cytoplasm:
Contains speci.c
granules 7B cell isranulocyte
Aranules have
a`nity for 9othbasic and eosindyes.
8e( other organelleslycogen particlesranules:
)pecic granules
+primary-
3zurophilicgranules+secondary$ non'specic lysosomes-
ertiary granules
agents at the site ofin2ammation.
R. 9asophil" structure$ ultrastructure and functions
)tructure Jltrastructure *unctionshe same size as
neutrophils+ucleus:3lsopolymorphonuclear"usually bi'lobed or tri'lobed.Cytoplasm:amed basophil becausethe numerous largegranulesin theircytoplasm stain withbasic dyes 7B blue
appearance herefore granules
cover 9Gnucleus andCytoplasm
+uclues:
eterochromatin alsolocated at the peripheryand euchromatincentrallyranules:' )pecic +basophilic-' 3zurophilic +non speciclysosomes found in allleu6ocytes-
9asophils bind an
antibody7gE$ through high'a`nity*c receptors expressedon their cell surface. hesubse,uent exposure to$and reactionwith$ the antigen+allergen- specic for (gEtriggers the activation ofbasophils and the releaseof "asoacti"e agentsfrom cell granules.
FH. Eosinophil" structure$ ultrastructure and functions
)tructure Jltrastructure *unctions3bout the same size asneutrophils+uclues:9asophilicPolymorphonuclear:nucleus is typically bi'
+ucleus:3s in neutrophils$ thecompact heterochromatinof eosinophils is ad>acentto the nuclear envelope$whereas the euchromatin
Eosinophils areassociated with allergicreactions$ parasiticinfections$ and chronicin2ammation.
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lobedCytoplasm:Contains largeacidophilic granuleswhich cover thecytoplasm7B cannot see
whether the cytoplasm isacidophilic or basophilic
is located in the centre ofthe nucleus.8e( organellesranules:
)pecic +large
eosinophilic-
3zurophilic +non
specic lysosomes-
F. %onocyte" structure$ ultrastructure and functions
)tructure Jltrastructure *unctionsLargest of all theleu6ocytes"
#iameter" Q
micrometres+ucleus:
ypically more indentedthan other leu6ocytes 7B6idney shaped
appearance9asophilic*granulocyte nucleusis non'segmented so cellis described asmononuclearCytoplasm:9asophilic/azurophilic
Organelles:
Aolgi apparatus
and centrioles arelocated in the?indented@ areaaround the nucleus
4E4$ )E4 and
small mitochondriaranules:
3zurophilic
granules+lysosomescontained in allleu6ocytes-
#uring in2ammation$ themonocyte leaves theblood vessel at the site ofin2ammation$transforms into atissue macrophage$andphagocytosesbacteria$other cells$ and tissue
debris. 4emain in the
blood for onlyabout ! days.
F=. Lymphocyte" structure$ ultrastructure and functions
)tructure Jltrastructure *unctionshree groups oflymphocytes can beidentiedaccording to size" small$medium$ and largelymphocytes$ rangingin diameter from F to !H
Organelles:
Aolgi$ ribosomes$
mitochondria allvary in amountaccording to sizeof lymphocyte
7mmunocompetentcells +i.e.$ cells that havedevelopedthe capacity to recognizeand respond to antigensand arein transit from one
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micrometres+ucleus:
4ound
!ononuclear
+non'segmented-
9asophilic
Large and occupies
most of the cellCytoplasm
3ppears as a
small$ blue ringaround nucleus+contains onlyazurophilicgranules
4ibosomes 7B
blue appearancedue to slightbasophilia
ranules:
3zurophilic
lymphatic tissue toanother-
8unctionally diIerentlymphocytes:T cells have a long life
span and are involved incell mediatedimmunity.) B cells have variablelife spans and areinvolved in theproduction of circulatingantibodies.) +J cells areprogrammed during theirdevelopment to6ill certain virus'infected
cells and some types oftumorcells.
hey also secrete
an antiviral agent$interferon
F!. 8latelet" structure$ ultrastructure and functions
)tructure Jltrastructure *unctions0mallcytoplasmicfragments derived frommega6aryocytes.
='! micrometres in
diameter!embranebounded
*nucleate
)tructural organization ofthe thrombocytecytoplasm categorizedinto four zones
he peripheral zoneconsists of the cellmembranecovered by a thic6surface coat ofglycocalyx.
' he integralmembraneglycoproteinsfunction asreceptors in
Continuous surveillanceof blood vessels$9lood clot formation$4epair of in>ured tissue.
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platelet function.he structural zonecomprises microtubules$actin laments$ myosin$and actin'bindingproteins that form a
:etwor6 supporting theplasma membrane.
' responsible formaintaining theplatelet@s discshape.
he organelle zoneoccupies the center ofthe platelet. (tconsists of mitochondria$peroxisomes$ glycogenparticles$
and at least three typesof granules dispersedwithin thecytoplasm.
he membrane zone