Epithelium Flashcards

1
Q

occluding junctions are also called

A

tight junctions, or Zonula Occludens

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2
Q

occluding junctions forms a ring or circumferential band around the cell

A

serves as a diffusion barrier

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3
Q

outer leaflets of adjoining plasma membrane fuse

A

fusion occurs in band or belt like configuration around cell

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4
Q

the tight junction seal is created by two transmembrane proteins

A

occludins, and claudins, form a zipper seal

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5
Q

zonula occludens proteins

A

ZO-1, ZO-2, ZO-3

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6
Q

zonula occludens proteins interact with cytoskeleton actin filaments

A
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7
Q

ZO-1 and ZO-2 proteins are vulnerable for toxins and pathogenic virus

A

example is Cholera toxin, cytomegalovirus, dengue virus

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8
Q

Toxins produced by helicobacter pylori damage the occluding junctions of the gastric mucosa and cause leaking of HCL in stomach wall

A

leads to bleeding and peptic ulcers

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9
Q

blood brain barrier

A

occluding junction that prevents proteins in the circulating blood entering nerve tissue

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10
Q

zonula occludens restrict movement of lipid rafts

A
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11
Q

functions of zonula occludens

A

prevents molecules crossing the epithelium, prevent a paracellular pathway

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12
Q

functions of zonula occludens

A

restrict movements of membrane lipids and proteins at the apical domain into the lateral and basal domains

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13
Q

functions of zonula occludens

A

maintain two distinct membrane domains- Apical, and basolateral

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14
Q

Anchoring junctions have two types

A

zonula adherens and macula adherens (desmosome)

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15
Q

zonula adherens are

A

continuous band like adhesion

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16
Q

macula adherens or Desmosomes

A

localized spot adhesion

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17
Q

zonula adherens are formed by

A

binding of transmembrane proteins E-cadherins (epithelial cadherins) of neighboring cells

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18
Q

zonula adherens are calcium dependent

A
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19
Q

macula adherens or desmosomes

A

provide strong attachment to cells

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20
Q

macula adherens contains large proteins of the cadherin family such as

A

desmogleins, desmocollins

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21
Q

macula adherens have cytoplasmic ends of the proteins bind with plakoglobins

A

plakoglobins bind with desmoplakins

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22
Q

gap junctions or nexuses

A

channels on the lateral surface of adjoining cells

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23
Q

gap junctions

A

allow direct passage of signaling molecules from one cell to another

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24
Q

gap junctions consist of transmembrane channels called

A

connexons

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25
Q

connexons are made up of

A

six connexin proteins

26
Q

connexons on one cell membrane precisely align with corresponding connexons that allow

A

communication between cells and exchange of ions

27
Q

anchoring junctions attach cell to extracellular matrix by two types

A

Hemidesmosomes and focal adhesions

28
Q

hemidesmosomes are

A

half desmosome located on the basal surface of cell

29
Q

hemidesmosomes - TEM exhibits intracellular attachment plaques on cytoplasmic side of plasma membrane

A
30
Q

Hemidesmosomes Attachment plaques are composed of desmoplakins such as

A

plectin, erbin, BP 230

31
Q

Hemidesmosomes attachment plaques are attached to basal lamina by transmembrane proteins :

A

integrins, BP 180 or type XVII collagen (also known as anchoring filaments)

32
Q

Bullos Pemphigold

A

rare autoimmune skin condition-high levels of antibodies are formed against BP230 and or BP180
Absence of the functional BP230 causes blistering of the skin (fluid build up between epidermis and dermis)

33
Q

focal adhesions

A

connect the cytoskeleton to the extracellular matrix by linking actin filaments to the extracellular matrix protiens

34
Q

focal adhesions consist of 3 faces

A

cytoplasmic face- actin filaments
transmembrane face- integrins
extracellular face-laminin and fibronectin

35
Q

epithelial glands form during development by proliferation of epithelial cells

A
36
Q

Some Epithelial glands retain their continuity witht the surface via a duct

A

Exocrine glands

37
Q

Some epithelial glands lose this direct continuitity with the surface when their ducts degenerate…

A

Endocrine Glands

38
Q

Endocrine glands discharge secrete into blood system

A
39
Q

exocrine gland can be unicellular

A

goblet cells

40
Q

exocrine glands can be multicellular, secretions are delivered into ducts

A

sweat glands

41
Q

Endocrine glands

A

glands without ducts, secretions are released into blood stream

42
Q

Unicellular Exocrine glands

A

release products from epithelial cells

43
Q

goblet cells

A

unicellular exocrine gland, synthesize and secrete mucus
essential role in maintaining protective mucosal barrier

44
Q

In ulcerative colitis, goblet cell number and size drastically decrease

A
45
Q

Multicellular Exocrine Glands-two features of morphological classification

A

duct structure and shape of secretory unit

46
Q

Multicellular exocrine glands-based on duct structure

A

simple-single branched duct, large intestine glands
compound-branched duct, ex salivary glands

47
Q

Multicellular exocrine glands are based on shape of secretory units

A

tubular or aveolar- example of sweat glands
acinar- rounded and saclike-salivary glands

48
Q

merocrine gland is most

A

common type of secretion

49
Q

Classification of Multicellular exocrine glands

A

Merocrine, holocrine, apocrine

50
Q

Merocrine classification

A

most common type
Secretion is released by exocytosis
example sweat gland

51
Q

Holocrine classification

A

whole cell ruptures during release of product
ex. sebaceous gland

52
Q

Apocrine classification

A

Apical cytoplasm is lost with the secretion
example of mammary gland

53
Q

Multicellular exocrine glands classification

A

Serous, mucous, mixed (serous and mucous secretion)

54
Q

Mucous Membrane or mucosa

A

lines cavities that connect with outside of body
example GIT, respiratory ducts, urogenital tract
consists of: diverse types of epithelium, basal lamina, and lamina propria
May contain glands that secrete mucus

55
Q

serous membrane of serosa

A

lines closed cavities-peritoneal, pleural, pericardial cavities
consists of : simple squamous, mesothelium, basal lamina, and underlying this loose connective tissue
DOES NOT contain glands
Two components: Parietal and Visceral

56
Q

Parietal serous membrane lines

A

body cavity

57
Q

Visceral serous membrane covers

A

organs in the body cavity

58
Q

parenchyma

A

functional tissue of an organ as distinguished from the connective and supporting tissue

59
Q

stroma

A

supporting connective tissue with blood vessels and nerve fibers

60
Q

list differences between serous glands, mucous glands, and mixed glands

A