Epithelial Tissue Morphology Flashcards

1
Q

epithelia functions

A

trans-epithelial transport,

secretion and synthesis and absorption,

protection,

generation of movement over apical surface (thanks to cilia)

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2
Q

how are epithelia classified?

A

dependent on their shape and number of layers

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3
Q

different types of shape

A

cuboidal, flat and columnar

transitional- capacity to change shape

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4
Q

different types of layers

A

simple epithelia- one layer

stratified epithelia- many layers

pseudostratified- appear as if many layers however only one

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5
Q

another name for transitional epithelium

A

uroepithelium

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6
Q

how else can epithelia be classified and give the classes?

A

dependent on function

absorptive, mechanical and secretory

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7
Q

two different types of surface specialisations + functions

A

cilia- movement of particles

microvilli- increase surface area for absorption

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8
Q

simple squamous location

A

blood vessels, loops of Henle

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9
Q

simple cuboidal location

A

kidney

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10
Q

simple columnar location

A

alimentary tract (nucleus is at the base of all cells)

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11
Q

stratified squamous location

A

skin

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12
Q

stratified squamous structure + function

A

many flat layers, that begin more cuboidal and become more squamous nearer the surface

differentiator cell found at the top

protect against abrasion and infection

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13
Q

rarest epithelia + location

A

stratified cuboidal

sweat glands and ducts

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14
Q

pseudostratified columnar cells location + structure

A

respiratory epithelium

nucleus appears in different places, cillia on surface

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15
Q

location of transitional epithelium + function

A

urinary tract (bladder)

capacity to alter their width, able to distend or contract the bladder

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16
Q

cilia structure + function

A

microtubulin core

move back and forwards to repel mucus out of the respiratory tract, dyenin

17
Q

microvilli structure + function

A

microfilament actin core

increase SA of small intestine for absorption, forming a brush border

18
Q

what separates epithelia from connective tissue?

A

basement membrane

19
Q

what is the basement membrane?

A

a thin, fibrous, non cellular matrix that separates the lining of an internal or external body surface from the underlying connective tissue

20
Q

structure of basement lamina

A

composed of three layers

lamina lucida- layer closest to the epithelia (not electron dense)

lamina densa (electron dense)- contains perlecan (heparan rich GAG)

lamina reticularis- also associated with reticular fibres of the underlying connective tissue

contains collagen VII anchoring fibrils and fibrillin microfibrils

21
Q

basement membrane function

A

anchors the epithelium down to loose connective tissue (dermis/lamina propria)

acts as a mechanical barrier, preventing the infiltration of malignant cells

cell differentiation

differentiates between apical and basolateral domains

22
Q

key feature of epithelia

A

polarity of cells

23
Q

two different domains

A

apical- external surface

basolateral- internal surface

24
Q

what does the basolateral domain consist of?

A

cell unctions

25
5 main types of cell junctions
tight- occluding junctions adhesive gap desmosomes and hemidesmosomes
26
gap junctions structure + function
formed of connexins allow chemical and electrical signals to diffuse through cells rapidly, forming syncytiums
27
tight-occludng junctions structure + function
zona occludens, a band formed near the apical region of the cell formed of occludins and other adhesion molecules prevent intercellular transport
28
explain adhesive junctions
bind cells together, forming the zonula adherens cadherin proteins linked to actin cytoskeleton
29
desmosome location
localised spot like adjesions on the lateral sides of plasma membranes
30
desmosome structure
desmosome intermediate filament complexes a network of cadherin proteins, linker proteins and keratin intermediate filaments desmogleins and desmocollins
31
desmosome function
strong cell to cell adhesions that are found in tissues that experience intense mechanical stress, such as cardiac muscle, bladder tissue
32
hemidesmosome location + function
attach basal epithelial cells to lamina lucida (basement membrane)
33
hemidesmosome structure
integrin and plectin membrane spanning components no cadherin bind to keratin intermediate filaments in the cytoskeleton
34
two types of movement through epithelia defined
transcellular - through the cells paracellular- between the cells
35
what determines which transport will be favoured?
type and number of junctional complexes
36
two types of epithelia
leaky, tight
37
disorder of the junctional complexes
pemphigus
38
explain pemphigus
antibodies produced against adherens and desmogleins in the skin no desmosomes cells become unglued from each other, resulting in blisters and sores