Lecture B1 Flashcards

1
Q

epithelial cells make up a large component of the body (less than erythrocytes) because _____

A

they forms the inside & outside layers

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2
Q

epithelial cells are the building ____

A

blocks of tissues

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3
Q

3 main functions of epithelial cells

A

-covering, lining surfaces
-absorption
-secretion of enzymes, sweat, mucous etc.

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4
Q

5 common features of epithelial cells

A

-Layer(s) of tightly adhering cells to prevent leakage
-Show a polarity (apical & basolateral)
-Can have specialized apical surfaces
-Lipid rich
-Largely avascular

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5
Q

Epithelial cells sits on ___ which is ____

A

-basement membrane
-the interface of epithelial cells and connective tissue

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6
Q

since epithelial cells are avascular, they get their blood supply from ____

A

the surrounding connective tissue which has capillaries

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7
Q

epithelial cells come from _____ (embryonic layer)

A

all layers (ectoderm, endoderm, mesoderm)

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8
Q

epithelial cells from ectoderm form _____ (4)

A

skin, lining of mouth, nose, anus

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9
Q

epithelial cells from endoderm form _____ (2)

A

lining of airways, digestive system

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10
Q

epithelial cells from mesoderm form _____ (2)

A

lining of vessels of lymphatic and cardiovascular
(endothelium)

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11
Q

Epithelial cells were histologically classified by _____ (3) because _______

A

-cell shape, cell layers, nuclei shape
-epithelial cells are lipid rich and hard to see with light microscopy

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12
Q

epithelial cells are characterized by ___ (2)

A

-number of layers
-shape of top layer of cell

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13
Q

simple epithelial cell means ____

A

one layer

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14
Q

stratified epithelial cell means ____

A

two or more layer

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15
Q

squamous epithelial cell means ____

A

flat cell

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16
Q

cubiodal epithelial cell means ____

A

cubed shaped cell

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17
Q

columnar epithelial cell means ____

A

columned shaped cell

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18
Q

columnar epithelium is often ____

A

ciliated on the apical surface (have modified apical surface)

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19
Q

pseudo stratified epithelial cell (descr.)

A

-cells look stratified (nucleus at different levels) but all the cells touch the basement membrane
-not all the cells with reach apical surface

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20
Q

simple squamous epithelium location

A

-air sacs of lungs
-lining of the heart, blood vessels, lymphatic vessels

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21
Q

simple squamous epithelium function

A

-allows materials to pass through by diffusion
-filtration
-secretes lubricants

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22
Q

simple cuboidal epithelium location

A

-ducts
-secretory portions of small glands
-kidney tubules
-ovary and thyroid

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23
Q

simple cuboidal epithelium function

A

-secretion and absorption
-covering
-high level of active transport

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24
Q

simple columnar epithelium location

A

-ciliated tissues in bronchi, uterine tubes, uterus
-non-ciliated tissues/smooth are in digestive tract, bladder

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25
Q

simple columnar epithelium function

A

-absorption
-secretions mucous & enzymes
-protection, lubrication

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26
Q

pseudo stratified columnar epithelium location

A

-ciliated tissue in the trachea & upper respiratory tract
-bronchi and nasal cavity

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27
Q

pseudo stratified columnar epithelium function

A

-secretes mucous, ciliated tissue moves particles trapped in mucus
-protection

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28
Q

stratified squamous epithelium location

A

-lines the esophagus, mouth, vagina
-(keratinized/dry) = skin/epidermis

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29
Q

stratified squamous epithelium function

A

-protects against abrasion
-secretion, prevents water loss
-(keratinized/dry) = protection, prevents water loss

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30
Q

stratified cuboidal epithelium location

A

-sweat glands
-salivary glands
-mammary glands

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31
Q

stratified cuboidal epithelium function

A

-protective tissue
-secretion

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32
Q

stratified columnar epithelium location

A

-male urethra
-ducts of some glands

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33
Q

stratified columnar epithelium function

A

-secretes and protects

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34
Q

transitional epithelium (descr.)

A

-type of stratified epithelium
-changes shape when stretched
-relaxed: looks cuboidal
-stretched: looks squamous

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35
Q

transitional epithelium location

A

-lines bladder, urethra, ureters

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36
Q

transitional epithelium function

A

-allows the urinary organs to expand and stretch
-protection

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37
Q

All epithelial tissue, regardless of functions, have _____

A

-apical junctions to maintain the tight separation of apical and basolateral compartments (creates polarity)

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38
Q

apical junctions prevents ____

A

the paracellular movement of solutes

39
Q

Absorption (def.)

A

process of transport from an organ or duct’s lumen to capillaries near the epithelial basement membrane and involves movement from the apical to the basolateral cell membrane domains

40
Q

Secretion (def.)

A

involves transport in the other direction from the capillaries into a lumen

41
Q

Features of typical epithelial absorptive cells

A

-apical membrane has a brush border/microvilli to increase surface for transport/absorption
-endocytosis, pinocytosis, transcytosis
-basal membrane has invaginations which associate with mitochondria

42
Q

endocytosis (def.)
pinocytosis (def.)
transcytosis (def.)

A
  • uptake of things outside the cell (general classification)
    -uptake of dissolved solutes
    -vesicular transport of macromolecules from one side of a cell to the other
43
Q

glands (def.)

A

specialized secreting tissues formed from epithelial tissue in the fetal stage

44
Q

glands are formed by the ____

A

invaginations of epithelial cells in to CT due to TF, signals

45
Q

exocrine gland (def.)

A

-maintain the connection to the overlying epithelium via a duct

46
Q

endocrine gland (def.)

A

-lose the connection to the overlying epithelium

47
Q

exocrine gland function

A

Secrete specific substances to other organs or body surface via the duct

48
Q

endocrine gland function

A

-Produce hormones
-Are rich in capillaries that absorb secreted hormones

49
Q

secretory cells of endocrine gland are arranged in _____

A

irregular cords or rounded follicles

50
Q

exocrine glands can come in different structures: _____

A

-simple (ducts don’t branch)
-compound (ducts from different secretory unit converge to form a large duct)

51
Q

parts of exocrine gland

A

-duct
-secretory portion/acinus

52
Q

exocrine secretory portion can also be ____

A

branched

53
Q

3 types of secretion by exocrine glands

A

-merocrine gland: exocytosis of vesicles/granules on apical side; most common
-holocrine gland: secretion of the entire terminally differentiated cells
-apocrine gland: secretion of apical membrane (pinched off(

54
Q

merocrine gland typically secrete ____ & gland example? holocrine? apocrine?

A

-protein/glycoprotein (ex. salivary gland)
-lipids (ex. sebaceous gland)
-large secretions (ex. mammary gland)

55
Q

How do epithelial cells stick together?

A

Intercellular adhesion and other junctions

56
Q

Cell junctions in mammalian cells

A

-Tight junctions
-Adherens junctions
-Desmosomes
-Gap junctions
-Hemidesmosome

57
Q

Tight junctions descr.

A

-most apical.
-Seals neighbouring cells together in an epithelial sheet to prevent leakage of molecules between them
-associated with actin filaments, microtubules

58
Q

Adherens junction descr.

A

joins actin bundles in one cell to a similar bundle in another cell

59
Q

Desmosomes descr.

A

joins the IFs in one cell to those in a neighbour

60
Q

Gap junction descr.

A

allows passage of small water soluble ions and molecules between cells; “holes between cells”

61
Q

Hemidesmosome descr.

A

anchors IFs in a cell to the basal lamina

62
Q

Tight junctions (aka _____ )

A

occluding junctions

63
Q

Tight junctions and Adherens junctions are composed of _____

A

protein complexes

64
Q

anchoring junctions (3)

A

-adherens junction
-desmosome
-hemidesmosome

65
Q

gap junctions (aka ____)

A

communicating junction

66
Q

Tight junctions includes ______ and forms ______ and contains ridges to ______

A

-occludins, Claudins and ZO1 proteins
-a continuous band around the cell
-prevent passive flow of molecules between cells

67
Q

Adherens junctions contains ______ which forms ______

A

-cadherins (ex. E-cadherins)
-homodimers in the plasma membrane of each interacting cell

68
Q

Adherens junctions are ___-dependent

A

Ca++ (occurs in the presence of calcium)

69
Q

Adherens junctions: The extracellular domain of one cadherin dimer binds to ______

A

-the extracellular domain of an identical cadherin dimer on the adjacent cell.

70
Q

Adherens junctions: The intracellular tails of the cadherin proteins bind to ______

A

-anchor proteins (α-catenin, β-catenin) that tie them to actin filaments.

71
Q

______ & ______ together of Adherens junction form a _____

A

-Cadherins
-a/B-Catenin
-stabilizing strong belt like structure that encircles the cell

72
Q

Desmosomes are _____ points of intercellular contact that ______

A

-button–like
-rivet cells together

73
Q

Desmosomes are anchoring points for _______ ( ______ in epithelial cells)

A

-intermediate filaments
-keratin filaments

74
Q

Desmosomes forms a cytoplasmic plaque containing _____ & bound to ______ extracellularly

A

-plakoglobin and desmoplakin bind to IFs
-cadherin family proteins desmoglein and desmocollin

75
Q

Hemidesmosomes (half desmosome) while
similar in appearance to desmosomes, they
include the adhesion proteins called ______
.

A

-integrins rather than cadherins

76
Q

Gap junctions: A ______ gap between cells formed by channel forming proteins called _______. Gap is formed by _______

A

-2-4 nm
-connexons
-6 transmembrane connexin subunits

77
Q

Similar to hemidesmosomes another adhesion complex, _______, anchor cells to the underlying basal lamina (basement membrane)

A

-Focal Adhesions (FAs)

78
Q

Focal Adhesions are formed by ____________ of which extracellular domain bind to extracellular matrix (proteins) and the
cytoplasmic tail of ______ via several intracellular anchor proteins such as ________

A

-transmembrane integrin heterodimers (a and β subunits)
-β subunit binds indirectly to actin
-actinin, talin or filamin and vinculin.

79
Q

Focal Adhesions vs Hemidesmosomes

A

-focal adhesion bind actin to ECM
-hemidesmosomes bind IF (keratin) to ECM
-both use integrins (transmembrane)

80
Q

Changing in protein make up of tight junctions changes ____

A

permeability of epithelial tissue

81
Q

tight junctions major function? adherens junction? desmosome? hemidesmosome? gap junction?

A

-seals cell together, prevents passage of molecules
-strengthens tight junctions
-strengthens tissues
-anchor to basal lamina
-allows movement between cells

82
Q

tight junctions loss leads to _____ ? adherens junction? desmosome? hemidesmosome? gap junction?

A

-bad blood-brain barrier
-allows for metastasis of cancer cells
-loss of cohesion of cells
-skin blistering
-deafness & peripheral neuropathy

83
Q

proteins that make up cytoskeleton

A

-actin (smallest)
-microtubules (biggest)
-intermediate filaments

84
Q

actin cytoskeleton descr.

A

-determine shape of cell surface
-needed for cell movement
-needs binding to other accessory and motor proteins
-constantly changing (constant state of flux)
-temporary & permanent

85
Q

microtubule cytoskeleton descr.

A

-determine position of membrane enclosed organelles
-direct intracellular transport
-stiffer than actin filaments

86
Q

intermediate filament cytoskeleton descr.

A

-provide mechanical strength and resistance to shear and bending stress
-filaments composed of smaller subunits of elongated fibres (acidic and basic keratins in epithelial cells)
-highly resistant to bending/stretching forces

87
Q

Actin assembly

A

-actin globular monomers (G-actin) spontaneously nucleated (unfavourable) or by nucleation-promoting factors (NPFs) (Formin/Arp 2/3) to form actin filament (F-actin)

88
Q

actin filaments and microtubules are _____

A

polarized (+/- sides)

89
Q

microtubule assembly

A

-tubulin dimers intrinsically self-assemble to form protofilaments which are arranged on NPFs like ɣ-TuRC to form microtubules

90
Q

Junctions and the cytoskeleton are important for function of an epithelial cells in terms of ______

A

-targeting proteins to the proper location in a cell

91
Q

To ensure selective targeting of proteins to establish apical/basal domains: ______

A

1) Selective targeting of a protein to specific cell surface domain
2) Selective stabilization of a protein at a specific cell surface domain

92
Q

Apical /Basal polarity of plasma membrane is needed for _________

A

-vectorial trafficking or secretion of proteins, solutes,
ions.

93
Q

Cytoplasmic polarity can generate ______ after division for tissue development

A

-different cell progeny

94
Q

Apical and Basal surfaces have different ______

A

-proteins and lipid components