Epithelia Flashcards

1
Q

Why is it important that epithelial cells divide rapidly?

A
  • To have a quick turnover –> due to damage, infection
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2
Q

Primary cilia

A

Non-motile, present in non-dividing cells

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3
Q

Mucous glands

- structure x2

A
  • Flat, dense nuclei

- Foamy cytoplasm

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4
Q

Serous glands

- structure x2

A
  • Round vesicular nuclei

- Eosinophilic cytoplasm

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5
Q

Simple epithelium occurs where….

A

There’s diffusion, absorption, secretion etc.

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6
Q

Stratified epithelium occurs where…

A

Protection is needed (as there are more layers)

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7
Q

Qualities of simple squamous x4

A
  • Single layer
  • Thin flattened cells w central nucleus
  • Close proximity (no gaps)
  • Some secretion
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8
Q

Mesothelium

  • type of endothelium
  • where
  • function
  • example
A
  • simple squamous
  • lines body cavities
  • secretes fluid –> less friction
  • e.g. pleura, peritoneum
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9
Q

Endothelium

  • type of endothelium
  • where
  • function
  • variations in structure…
A
  • simple squamous
  • lines blood vessels
  • secretes fluid –> less friction
  • can be almost impermeable vs having fenestrae (allows different molecules through)
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10
Q

Blood brain barrier

- function x2

A
  • Protects brain from infection
  • Restricts passage of potentially harmful molecules
    BUT
  • Allows essential ones through (O2, nutrients, ALSO drugs, alcohol etc)
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11
Q

Qualities of simple cuboidal x2

A
  • Round, central nucleus

- Approx. equal height & width

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12
Q

Qualities of simple columnar x1

A
  • Basal nucleus
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13
Q

Small Intestine

  • type of epithelium
  • where specifically
  • why this one
  • surface modifications x2
A
  • Simple columnar
  • Villi
  • More cytoplasm = more organelles for secretion/active transport
  • Microvillus brush border on apical surface
  • Goblet cells = release mucus, stopping pathogens binding
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14
Q

Modified columnar epithelium

- examples & their modification x2

A
  • Villi (GI tract) –> + goblet cells & microvillus brush border
  • Kidney –> microvillus brush border
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15
Q

Qualities of pseudo-stratified columnar epithelium

A

Appears to have multiple layers, but just nuclei at different levels, as not all cells reach the apex

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16
Q

Respiratory epithelium

  • type of epithelium
  • types of cells
  • adaptation
A
  • Pseudo-stratified ciliated columnar
  • Columnar, goblet, basal
  • Cilia –> protection –> as pathogens transported upwards towards larynx
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17
Q

Stratified squamous:

  • Apical layer (+ the 2 variations)
  • Basal layer
  • Function
A
  • Squamous epithelial cell –> of the keratinising or non-keratinising type
  • Columnar/cuboidal
  • Protection –> abrasion & pathogens
18
Q

Stratified squamous keratinised

  • example
  • function
  • basal layer structure
  • apical layer structure
A
  • Lips, skin
  • Resists dehydration, abrasion
  • Mainly keratinocytes
  • Mainly dead cells, consisting of keratin
19
Q

Keratinocytes

what happens as they move basal –> apical

A
  • As become more apical, fill w keratin
  • Junctions fill w waxy substance, restricting nutrients –> cells die
  • At apical surface, mostly hard, dead, keratin-filled cells
20
Q

Stratified squamous non-keratinised

  • example
  • function
A
  • Tongue, oesophagus

- Resists abrasion BUT not dehydration

21
Q

Desquamation

A

When epithelial cells = worn off and shed

22
Q

Oesophagus

  • type of epithelium
  • why this structure
  • wet epithelium so subject to….
A
  • Stratified squamous non-keratinised
  • lots of layers to protect from abrasion
  • abrasion BUT not dehydration
23
Q

Transitional epithelium

  • example
  • structure
  • ‘transitional’ as
  • adaptation that goes w this
A
  • Bladder
  • Crowded basal layers, which extend towards lumen
  • Can change shape –> e.g. become more distended
  • Lots of tight junctions –> prevent leakage
24
Q

Simple squamous

  • function x2
  • example x2
A
  • Rapid diffusion, smooth surface

- Endothelium, mesothelium

25
Q

Simple cuboidal

  • function x2
  • example x2
A
  • Secretion, absorption

- Liver, kidneys

26
Q

Simple columnar

  • function x2
  • example
A
  • Secretion, absorption

- GI tract

27
Q

Pseudostratified

- example

A
  • Respiratory epithelium
28
Q

Stratified squamous (keratinised)

  • function
  • example x2
A
  • Protects from abrasion & dehydration

- Lips, skin

29
Q

Stratified squamous (non-keratinised)

  • function
  • example
A
  • Protects from abrasion

- Oesophagus

30
Q

Stratified cuboidal

- example

A
  • Sweat glands
31
Q

Stratified columnar

  • function
  • example
A
  • High protection

- Male urethra

32
Q

Transitional

  • function
  • example
A
  • Changes shape as stretched

- Bladder

33
Q

Tight junctions

- function x2

A
  • Join cells together

- Helps control passage of molecules BETWEEN cells

34
Q

Membrane proteins: connexin

A

Communication between cells

35
Q

Membrane proteins: occluding, claudin

A

Binding of cells

36
Q

Adherens junctions

- function x2

A
  • Encircles cell –> stability

- Binds cells, linking cytosolic bundles, creating 1 functional unit

37
Q

Gap junctions

- function x1

A
  • Allows small molecules to pass between cells
38
Q

Desmosomes

  • function x2
  • subject to…
A
  • Strength
  • Strong cell attachment (as link filament networks)
  • Subject to abrasion
39
Q

Sealing strands

  • Where
  • Contain
  • More =
A
  • Within tight junctions
  • Actin, claudins, occludins –> amounts vary in diff. body parts
  • More sealing strands = more difficult to get through
40
Q

Routes for molecular movement x3

A
  • Between cells
  • Trans-cellular (through cells)
  • Paracellular (movement occurring in and out)
41
Q

Different roles of tight junctions x3

A
  • BARRIERS –> no movement
  • FENCES –> maintains distribution between membranes
  • GATES –> selective, regulated movement