Epithelia Flashcards

1
Q

What forms epithelium ?

A

Epithelial cells

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2
Q

What are the 4 tissue types ?

A

Epithelial
Nervous
Muscle
Connective

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3
Q

What is an epithelium ?

A

Epithelia form continuous sheets of cells.

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4
Q

Function of epithelia

A

Act as barriers :

Between the body and external world
Between fluid compartments within the body

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5
Q

How do epithelia transport molecules ?

A

Via absorptive & secretory processes

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6
Q

Epithelial Cell types

A

Cuboidal
Columnar
Squamous

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7
Q

Single Layer of cells

A

Simple epithelium

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8
Q

Basement Membrane

A

Each cell comes into contact with a basement membrane separating it from the underlying tissue

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9
Q

Cuboidal cells

A

Same cell height/width
Have a central nucleus

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10
Q

Columnar cells

A

Cell height is greater than width
Basal nucleus (near the basement membrane)

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11
Q

Squamous cells

A

Flat cells
Disc shaped nucleus

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12
Q

Simple cuboidal epithelium function

A

Secretion & Absorption

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13
Q

Simple cuboidal epithelium localisation
(4 places)

A

Kidney Tubules
Ducts
Secretory portions of small glands
Ovary surface

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14
Q

Simple columnar epithelium function

A

Absorption
Secretion of Mucus, Enzymes etc.

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15
Q

Simple columnar epithelium types

A

Ciliated
Non-Ciliated but with microvilli

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16
Q

Simple columnar epithelium localisation (non-ciliated)

A

Digestive tract
Gallbladder
Excretory ducts

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17
Q

Simple columnar epithelium localisation (ciliated)

A

Small bronchi
Uterine Tubes

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18
Q

Simple squamous epithelium function

A

Passage of materials by diffusion and filtration
Secretion of lubricating substances

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19
Q

Simple squamous epithelium localisation

A

Alveoli of Lungs
Blood Vessels
Lymphatic vessels
Kidney glomeruli

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20
Q

Simple pseudostratified epithelium

A

Looks like there are multiple layers
All cells are in contact with the extracellular matrix
Several ‘layers’ of nuclei

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21
Q

Simple pseudostratified epithelium types

A

Ciliated
Non-ciliated

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22
Q

Simple pseudostratified epithelium function

A

Secretion of mucus

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23
Q

Simple pseudostratified epithelium localisation (non-ciliated)

A

Large glands
Vas deferens

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24
Q

Simple pseudostratified epithelium localisation (ciliated)

A

Trachea
Upper respiratory tract

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25
Q

Multiple layers of cells

A

Stratified epithelium

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26
Q

Stratified cuboidal epithelium function

A

Protects underlying tissue

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27
Q

Stratified cuboidal epithelium localisation

A

Largest ducts of sweat glands
Mammary glands
Salivary glands

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28
Q

Stratified columnar epithelium function

A

Protection and secretion

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29
Q

Stratified columnar epithelium localisation

A

RARE !
Urethra
Large ducts of glands
Conjunctiva of eyes

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30
Q

Stratified squamous epithelium function

A

Protects underlying tissue

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31
Q

Stratified squamous epithelium types

A

Keratinised
Non-keratinised

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32
Q

Stratified squamous epithelium localisation (keratinised)

A

Epidermis of Skin

33
Q

Stratified squamous epithelium localisation (non-keratinised)

A

Oesophagus
Mouth
Vagina
Urethra
Anus

34
Q

Transitional epithelium

A

Several cell layers
Basal cells are cuboidal/columnar
Superficial cells are squamous like /dome shaped

35
Q

Transitional epithelium function

A

Stretches readily permitting distention of urinary organ

36
Q

Transitional epithelium localisation

A

Ureter
Bladder
Parts of urethra

37
Q

Types of simple epithelium

A

Squamous
Cuboidal
Columnar - (non) ciliated
Pseudo-stratified - (non) ciliated

38
Q

Types of stratified epithelium

A

Squamous - (non) keratinised
Cuboidal
Columnar
Transitional

39
Q

Junctional protein function

A

Connects cells to each other
Connects cells to basement membrane
Some allow intercellular communication
Enable POLARIZATION

40
Q

Junctional complexes
Top to Bottom

A

Tight Junctions
Adherens Junctions
Desmosome
Gap Junctions
Hemi-desmosomes

41
Q

Another name for tight junctions

A

Zonula occludens

42
Q

Tight Junction function

A

Hold together neighbouring epithelial cells
Prevents passage of molecules and ions. (permeability barrier)

43
Q

Which junction defines the apical/ basolateral boundary ?

A

Tight Junctions

44
Q

Another name for adhering Junctions

A

Zonula Adherens

45
Q

Adhering Junction function

A

Allows cell-cell adhesion via interaction between extracellular domains.

46
Q

Location of adhering junctions

A

Found directly beneath the tight junctions

47
Q

Another name for desmosomes

A

Macula Adherens

48
Q

What do desmosomes look like ?

A

Spot like adhesions arranged on the lateral surface of cells.

49
Q

Function of desmosomes

A

Allows cell-cell adhesion via interaction between extracellular domains.

Intracellular cytoplasmic tail associates with adaptor and signalling proteins.

50
Q

What cells have gap Junctions ?

A

Gap junctions are not specific to epithelial cells alone, nearly all cells have gap junctions.

51
Q

Structure of gap junctions

A

Consists of 2 connexons, one from each cell, each formed of 6 connexion subunits

52
Q

Function of gap junctions

A

Allows intercellular communication

53
Q

Hemidesmosomes function

A

Attach epithelial cells to the basement membrane

54
Q

Microvilli function

A

Enables absorption
Increases surface area
Central core of actin filaments

55
Q

Cilia

A

Longer than microvilli
Cilia move back and forth to move particles

56
Q

Stereocilia function

A

Longer than microvilli, as the actin filaments are longer

57
Q

Where are microvilli found ?

A

Small intestine
Proximal tube of kidney

58
Q

Where are cilia found ?

A

Oviduct
Respiratory Tract

59
Q

Types of membrane features

A

Keratin
Microvilli
Interdigitatons
Cilia

60
Q

What are membrane interdigitations ?

A

Involved in transport and intercellular adhesion.
Interlocking membrane folds of adjacent cells.

61
Q

Polarisation of Epithelial cells

A

Tight junctions form complexes between cells

This gives rise to an apical surface and a basolateral surface

62
Q

Function of polarisation of epithelial cells

A

Enables transport of ion, solutes and water

Often against their ionic and concentration gradients.

63
Q

2 types of trans-epithelial transport

A

Paracellular
Transcellular
(OR BOTH)

64
Q

Paracellular transport

A

Occurs between cells via Tight Junctions.
Epithelia are considered ‘leaky’ or ‘tight’ depending on TJ’s
Movement from tubule lumen to interstitial space

65
Q

Trans-cellular transport

A

Occurs through the cell
Crosses both apical and basolateral membranes
Requires transporters/channels
Moves ions against electrochemical gradient

66
Q

3 different places

Where does trans cellular transport occur ?

A

Intestine
Airway
Kidney

67
Q

What are the layers of skin ?

A

Epidermis
Dermis
Subcutaneous Tissue

68
Q

Epidermis structure

A

Keratinised epithelium
Some nerve endings

69
Q

Function of epidermis

A

Shedding and Regeneration of Skin, approx. 2g per day

70
Q

Dermis structure

A

Collagenous and elastin rich
Tough and Stretchy
Vascular and Innervated

71
Q

Function of dermis

A

Contains har follicles, arrestor pili muscles and some sweat glands

72
Q

Structure of Subcutaneous Tissue

A

Adipose fat store
Vascular and innervated
Contains sweat glands (eccrine and apocrine)

73
Q

Where are eccrine glands present?

A

Present on almost ALL skin
Water and some electrolytes

74
Q

Apocrine Glands

A

Lipid/protein rich secretion
‘Activate’ with puberty

75
Q

What features of the skin enable protection ?

A

Keratin, Collagen and Elastin

76
Q

What aids thermoregulation ?

A

Sweat glands, hair and arrector pili

77
Q

What feature of the skin is present for senses ?

A

Nerve endings allow recognition of :

  • Pain
  • Temperature
  • Fine touch
  • Proprioception
78
Q

What are Langer’s Lines

A

Specific lines of tension within skin