Epithelium Flashcards

1
Q

general features of epithelia

A

linked tightly together by intracellular junctions, found in the lining of all cavities and surfaces

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2
Q

major function of epithelia

A

barriers between two compartments

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3
Q

epithelium

A

free apical surface, and basal surface that rests on a non-living layer of ECM (basement membrane)

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4
Q

basement membrane

A

non living layer ECM, consists of true lamina (secreted by epi cells) and reticular lamina (secreted by conn. tissue cells)

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5
Q

classification of epithelia

A

simple, stratified, pseudostratified // squamous, cuboidal, columnar

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6
Q

simple epithelia

A

one layer of cells, all cells touch both free apical surface and basal surface touching basement membrane

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7
Q

stratified epithelia

A

more than one layer of cells, In a stratified epithelium, the apical or superficial layer of cells faces the free surface and is separated from the basal lamina by one or more layers of cells.

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8
Q

pseudostratified epithelia

A

all cells rest on the basal lamina, but only some have a free surface. arrangement of the nuclei is distinctive.

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9
Q

squamous features

A

wide, flat, nuclei bulging out of apical surface

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10
Q

cuboidal

A

cube-shaped. nucleus is round, and in the centre of the cell. cells that are wider than tall = low cuboidal

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11
Q

columnar

A

taller than wide. nucleus is elongated, and on the basal side

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12
Q

modifications

A

apical surface usually has modifications - microvilli, cilia, and stereocilia

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13
Q

parenchyma

A

secretory section of glandular tissue

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14
Q

types of tissues

A

epithelia, connective, nerve, muscle

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15
Q

places you find epithlia

A

sheets of cells lining cavities and open spaces.

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16
Q

functions of epithelium

A

barrier, protection, absorption, secretion, transport

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17
Q

how does epithelia protect?

A

abrasion resistance - layers of dead cells (skin), mucous secreting cells; line outside of digestive organs and protect as they all slosh and bump into each other

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18
Q

what does epi do to increase absorption + secretion?

A

fold a lot to increase SA

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19
Q

how much blood vessel content?

A

no blood vessels

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20
Q

types of apical specializations?

A

microvilli, cilia, stereocilia

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21
Q

microvili features

A

cylindrical projections; 0.5-1.0 microns, increase surface area for absorption, create a “brush border” pattern, seen in digestive tract and kidney, <50% size of nucleus

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22
Q

microvili structure

A

actin, hollow inside, cannot actively move, core joins actin cytoskeleton, cannot usually see individual microvili

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23
Q

stereocilia features

A

modified microvilli, very long (75% cell), sparse and ragged looking, found in inner ear and male reproductive system

24
Q

cilia features

A

10x bigger microvilli, pinched appearance (beer bottle), sweeping motion moves material, found in respiratory and female reproductive (egg and uterus), has dark line beneath it (basal body)

25
Q

cilia structure

A

microtubule skeleton (axenome), 9+2 arrangement of microtububles, anchor in cell = basal body = most important feature is dark line at the apical surface

26
Q

epithelia are tightly packed. what holds them together?

A

cell junctions: tight junctions, adherens junctions, gap junction, and desmosomes IN THAT ORDER.

27
Q

tight junction features

A

membranes are closely opposed, most apical of all the junctions, prevent movements between cells, chicken-wire/fishnet feature, occluding junction (no liquid can pass through)

28
Q

adherens junction features

A

apical lateral cell junctions (just below tight junction), encircle cell completely, long parallel densities (space), NOT occluding aka liquid will get past them, consist primarily of cadherins

29
Q

desmosome features

A

strong and lateral adhesion, static and structural, PROMINENT KERATIN FILAMENT WEB, parallel densities, usually straight, same cadherin famile as adherence junction, not concractile

30
Q

gap junction features

A

tightly opposed membranes, generally below adherens junctions, collection of pores (connexons), regulates cell to cell communication through free movement of small molecules between cells

31
Q

terminal bars features

A

all cell adhesion sites, artifact of fixation = vertical line with tiny little bulges

32
Q

types of basal specialization

A

basement membrane, cell substrate adhesion

33
Q

role of basement membrane

A

separates epithelium from connective tissue

34
Q

basement membrane layers

A

basal lamina of epithelial origin (laminins), reticular lamina of connective tissue origin (often see collagen fibrils)

35
Q

where find simple squamous? what surface modifications would you find?

A

lining all cavities, and all blood vessels, found where exchange occurs; no surface modifications

36
Q

what is mesothelium

A

lines all organs; simple squamous

37
Q

what is endothelium

A

lines all blood vessels; simple squamous

38
Q

where find simple cuboidal? what are its functions? what surface modifications would you find?

A

lining tubes and glands; secretory and absorpative; mv/c/sc

39
Q

where find simple columnar? what surface modifications would you find?

A

lines tubes (kidney, gallblader); apical modifications (mc/c/sc)

40
Q

where would you find ciliated simple columnar cells?

A

oviduct only; no goblet cells present

41
Q

where would you find simple columnar cells with microvili?

A

digestive tract - goblet cells are present here

42
Q

where would you find pseudostratified columnar cells? what surface modifications would you see?

A

respiratory tract - will be ciliated; male reproductive tract - will be stereociliated

43
Q

what layer should you look to in identifying which epithelium it is?

A

apical

44
Q

where would you find stratified squamous epithelium?

A

moist areas: nose, mouth, reproductive tract; where skin meets interior

45
Q

what distinct feature does keratonized stratified squamous epithelium have?

A

no nuclei

46
Q

where would you find transitional epithelium? why?

A

bladder - transition is very stretchy

47
Q

what features does transitional epithelium have?

A

pillow-like apical cells; these are flat when stretched (full) bladder

48
Q

what are the different glands? contrast them

A

exocrine and endocrine; exocrine secretes to free surface + is connected to surface + can form ducts; endocrine secretes to circulatory system + is not connected to surface + cannot form ducts + always round

49
Q

what are the different types of exocrine glands? define them.

A

merocrine/eccrine (secretes directly), apocrine (vesicle), and holocrine (whole cell)

50
Q

what is a goblet cell? what does it do?

A

unicellular exocrine gland; secretes mucous in the digestive and respiratory system

51
Q

what is a duct?

A

multicellular exocrine gland; it’s a specialised secretory unit

52
Q

which types of glands do you find in pancreas?

A

both exocrine and endocrine; the exocrine are secreting digestive enzymes and are arranged into ducts, while the endocrine are secreting insulin and arranged into cords

53
Q

why is epithelia so prone to cancer?

A

highly mitotic

54
Q

adenocarcinoma?

A

glandular cancer, excessive glandular tissue

55
Q

skin carcinoma?

A

common and metastatic, treated by excision

56
Q

are moles carcinoma?

A

no, they are a proliferation of melanocytes, and do increase susceptibility to cancer

57
Q

what do different burn degrees mean?

A

1st = surface epi 2nd = penetrates epi 3rd = penetrates connective tissue