Epithelium Flashcards

1
Q

What are the functions of epithelium?

A

1) PROTECTION of the underlying tissue from trauma
2) SECRETION: mucus, enzymes, hormones
3) ABSORPTION ( via endocytosis/pinocytosis) substances from lumen, eg intestine & kidney
4) TRANSPORT OF MATERIAL ON THE EPITHELIAL SURFACE (cilia) and TRANSCELLULAR TRANSPORT across epithelium (diffusion & vesicle mediated)
5) SELECTIVE PERMEABILITY of intercellular junction
6) SENSORY CELLS: taste bud, retina & hair cells in ear

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2
Q

Define simple epithelia

A

All cells contact the basement membrane and all cells reach the free surface

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3
Q

Define pseudostratified epithelia

A

All cells touch basement membrane but not all reach the free surface

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4
Q

Define stratified epithelia

A

Only basal layer of cells touch basement membrane, not all cells reach free surface

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5
Q

Define transitional epithelia

A

Type of stratified epithelia where the surface cells change between squamous and cuboidal shapes

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6
Q

Function of simple squamous epithelium

A

Involved in passive transport (diffusion) of gasses or fluids

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7
Q

Types of simple squamous epithelium

A

Endothelium
Mesothelium

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8
Q

Functions of simple cuboidal epithelium

A

Excrete, secrete, or absorb

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9
Q

Where can simple cuboidal epithelium be found?

A

Lining the small ducts and tubules, e.g. ducts of salivary glands and pancreas; collecting tubules of kidney

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10
Q

Where are simple columnar epithelium found?

A

Absorptive surfaces such as in the small intestine (with microvilli)

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11
Q

“Strongest protection against abrasion (not to dryness)” describes what kind of epithelium?

A

Non-keratinized stratified squamous

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12
Q

Where is non-keratinized stratified squamous found?

A

Oral cavity, pharynx, esophagus, anal canal, vagina, cervix

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13
Q

Mucus producing glands are associated with what kind of epithelium?

A

Non- keratinized stratified squamous

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14
Q

The only keratinized type of stratified squamous epithelium is the _______

A

Epidermis

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15
Q

Function of keratinized stratified squamous

A

Protects against abrasion

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16
Q

Where is stratified cuboidal epithelium found?

A

Lining the ducts of sweat glands in skin

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17
Q

What is the function of stratified columnar epithelium?

A

Just to provide lining of ducts

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18
Q

Where is stratified columnar epithelium found?

A

Lining of larger excretory ducts of exocrine glands, such as the salivary glands

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19
Q

Where is pseudostratified (columnar) epithelium found?

A

Respiratory tract

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20
Q

Where is pseudostratified (columnar) epithelium with stereocilia found?

A

Epididymal duct or the inner ear

21
Q

“Basal layer cells are cuboidal, intermediate cells are polygonal; and superficial are large, rounded, may contain two nuclei” describe what epithelium?

A

Transitional epithelium

22
Q

What are the top layer of cells in transitional epithelium called?

A

Dome cells or umbrella cells

23
Q

Where is transitional epithelium found?

A

Urinary system
Bladder
1/3 urethra

24
Q

“Finger-like projections extended toward the lumen”

A

Microvilli

25
Q

Function of microvilli

A

To increase surface area for the purpose of better and faster absorption

26
Q

Where is microvilli found?

A

Epithelium of small intestine and proximal convoluted tubules in kidney

27
Q

The core structure of microvilli is made up of

A

Actin

28
Q

The collection of microvilli on cells is called what?

A

Brush border

29
Q

Kinocilia (true cilia) is found where?

A

Respiratory and female reproductive tracts

30
Q

Function of cilia

A

Beat with a wave like synchronous rhythm propelling mucus in trachea or the ovum in fallopian tube

31
Q

What motor protein allows cilia to bend or move?

A

Dynein

32
Q

“Extremely long microvilli, readily visible with light microscopy. Actin core”

A

Stereocilia (non-motile cilia)

33
Q

A junctional complex encircles each cell in…

A

Simple cuboidal and simple columnar

34
Q

Zo Za Ma

A

Zonula occludens (tight junction)
Zonula adherens (adhering belt)
Macula adherens (desmosomes)

35
Q

What forms a collar around each cell beneath the apical surface?

A

ZO

36
Q

2 molecules of transmembrane protein ____, one from each membrane stitch the membrane together tightly (in ZO)

A

Claudin

37
Q

What are connected to ZO on the inside?

A

Actin

38
Q

Function of ZA and MA

A

Provide anchorage spots for the cytoskeleton (actin or intermediate filaments)

39
Q

What provide junctions on the basal surface of cells?

A

Hemidesmosomes & basal lamina

40
Q

Gap junctions aka _____

A

Communicating junctions

41
Q

Gap junctions contain numerous transmembrane channels called…

A

Connexons

42
Q

Each connexon is made up of…

A

6 connexins

43
Q

Functions of gap junctions

A

1) control growth, development, cell recognition, and differentiation
2) GJ more numerous in embryonic epithelia —> exchange of signaling molecules
3) also for electrical coupling of visceral and cardiac muscle cells —> permitting synchronous contraction

44
Q

Function of hemidesmosomes

A

Mediate adhesion of epithelium to basement membrane

45
Q

What is the basal lamina made up of?

A

Type 4 collagen, laminin, entactin, & proteoglycans

46
Q

Below the basal lamina is the _____ which is made up of ____

A

Reticular lamina
Type 3 collagen

47
Q

Glandular epithelium:
With ducts ______
W/O ducts _____

A

Exocrine gland
Endocrine gland

48
Q

Characteristics of goblet cells

A

Unicellular
Synthesis & secretion of mucus
Basal cytoplasm: organelles for synthesis

49
Q

Where are goblet cells found?

A

Respiratory & gastro-intestinal tracts