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Histology and Embryology > Epithelium Lecture > Flashcards

Epithelium Lecture Flashcards

1
Q

What are the characteristics of epithelial cells?

A 
Avascular 
Covers exterior body 
Lines internal cavities
Forms secretory portion of glands
Receptors for special senses
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2
Q

Does a basement membrane have cells?

A

Acellular

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3
Q

How does gas exchange happen at the basement membrane?

A

Diffusion

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4
Q

What are the domains of the epithelium cells?

A

Apical -> lumen/environment
Lateral-> neighbor cells and junctional complexes
Basal domain-> basement membrane

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5
Q

What is simple squamous epithlium? Where is it found?

A

Single layer polygonal cells
Thinnest tissue of body

-Bowman’s capsule kidney, respiratory spaces in lungs

LINES blood + lymphatic vessels for DIFFUSION

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6
Q

What is lining all blood + lymphatic vessels?

A

Simple squamous epithlium

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7
Q

What lines the atria + ventricles of the heart

A

Endocardium -> Simple squamous epithelium

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8
Q

What lines the walls + closed cavities of the body

A

Mesothelium -> simple squamous epithelium

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9
Q

What tissue forms ducts and glands?

A

Simple cuboidal epithelium

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10
Q

What are the characteristics of simple cuboidal epithelium?

A

Width similar to height

Nuclei are at similar levels, and nuclei is not much taller than cell

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11
Q

Where do you find simple cuboidal epithelium?

A

Kidney tubules, small ducts of exocrine

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12
Q

Do exocrine or endocrine glands have ducts?

A

Exocrine glands have ducts, endocrine glands do not

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13
Q

What are the characteristics of simple columnar epithelium?

A

Nuclei are lined up at basal portion of the cell

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14
Q

Where do you find simple columnar epithelium?

A

Small intestine, stomach lineing

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15
Q

What kind of epithelium has brush border? What is the brush border called?

A

Simple columnar epithelium, microvilli

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16
Q

What epithelium has goblet cells? What do they do?

A

Simple columnar epithelium, unicellular gland which secretes mucus

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17
Q

In stratified epithelium, what is the shape based off of?

A

The top most layer

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18
Q

What kind of epithelium are found in the esophagus, oral canal and the vagina?

A

Stratified Nonkeratinized epithelium

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19
Q

Where is stratified squamous epithelium kertanized found?

A

SKin

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20
Q

What happens when stratified squamous epithelium becomes keratinized?

A

lost nuclei, peel off

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21
Q

What epithelium is found in sweat glands/ large ducts of exocrine glands?

A

Stratified cuboidal epithelium

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22
Q

Where is stratified columnar epithelium found?

A

Largest ducts of exocrine, rectum, anus

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23
Q

Keratinization is only applicable to what type of epithelium?

A

Stratified squamous

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24
Q

Where is pseuostratified columnar epithelium found?

A

Trachea

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25
What is a characteristic of pseudo stratified epithelium?
All cells touch the base, only some reach the surface
26
What is transitional epithelium?
Specialized stratified epithelium *cobblestone
27
Where is transitional epithelium found?
Bladder, ureter, urethra
28
What are characteristics of transitional epithelium?
Impermeable to salts + water, plasma membrane hugely folded to stretch
29
What are exocrine glands? What are endocrine glands?
Exocrine secrete into ducts Endocrine secrete into nearby capillaries
30
What are merocrine secretion?
Exocrine Vesicle approches apical domain -> fuses with plasma membrane into extracellular space Plasma membrane can be returned via endocytosis and recycled
31
What is apocrine secretion?
Exocrine (milk) Apical cytoplasm is pinched off w/ secretions Mammary glands secrete LIPIDS by APOCRINE and milk casein by MEROCRINE
32
What is holocrine secretion?
Accumulates secretory product (sebum) and then disintegrates
33
Why are epithelium cells polarized?
For function and junction TIGHT JUNCTIONS ENSURE POLARITY
34
What are microvilli?
Closely packed "brush border" present in kidneys + intestine
35
What covers microvilli?
Glycocalyx coat of glycoprotein
36
What is within microvilli?
A core of actin filaments which are cross linked by actin binding proteins
37
What do actin filaments connect to within microvilli?
Actin filaments extend downward to cytoplasm where they attach to terminal web (horizontal actin filaments below base)
38
What is significant about stereocilia?
Non-motile (one cilium) Faciliate absorption Mechanical vibration (ear)
39
Are cilia motile? Where are they found
Cilia are motile (fluid over epithelial surface) -> can actively propel particles along a cell surface Found in respiratory tract
40
What are the characteristics of cilia?
Beat in synchronous pattern, arranged in orderly rows (respiratory tract) looks like hair at apical surface Basal bodies are thin, dark staining at base
41
What is a motile cilia composed of?
Microtubules in 9+2 pattern w/ doublet dynein arms Radial spokes extend from outer doublets to center Basal body has a core of 9 MT triplets, assembly INITIATED BY BASAL BODY
42
What is Kartagener's syndrome?
Structural abnormalities that results in ABSENCE of dyeing arms -> dysfunctional cilia -> bronchitis INFERTILITY in males/females bc motor proteins damaged
43
What are mono-cilia?
Non-motile primary cilia such as chemosensory, osmosensors, mechanosensors ESSENTIAL IN GASTRULATION (right left symmetry
44
What do junctional complexes between cells generate?
A functional barrier that maintains the cohesive nature of the epithelium -structure + polarity
45
What are junctional complexes made up of?
cell adhesion molecules (CAMs)
46
What are lateral specializations?
``` Zona occludens (tight junction) Zona adherens (adhesion belt) Desmosomes (spot weld) ```
47
Where are zona occludens found? What is characteristic of this?
Apically within the lateral domain, encircles the cell Not a continuous seal (a focal fusion of leaflets of plasma membrane) Focal fusion-> junctional proteins of adj cells transverse the plasma membrane and come into contact to occlude the ICS
48
What is Afadin + Nectin + JAMS? What is specific of afadin?
zonula occludent proteins (ZO1, ZO2, ZO3) -Faciliate interaction of occluden, claudin, JAMS w/ F-Actin Afadin is embryo lethal (ZO proteins attach transmembrane proteins to inside of cell and signaling molecules)
49
Where are tight junctions in the body? What do they prevent
BBB (astrocytes) - prevent lipids/membrane proteins from apical surface and lateral regions - signaling molecules to cell surface and link to actin filaments of cytoskeleton
50
What are claudins + occludins a member ?
tetraspan family of proteins (
51
What are nectins part of ?
transmembrane component of TJ, Ig Superfamily of proteins
52
Where does paracellular transport occur?
Across the ZO (water, electrolytes + small molecules depends on the tightness of the ZO)
53
What does the the tightness of ZO depend on?
Claudins to Occludins ration and the other proteins + aqueous channels in seal
54
What are TJ composed of?
Claudins
55
What are adherens junctions composed of?
E-Cadherin
56
What are gap junctions composed of?
Connexins
57
What are focal adhesions composed of?
Integrins
58
What is the characteristics of the zonula adherens?
Continuous belt that encircles the belt junction *Actin cytoskeleton* is linked Important for maintaining structure
59
In zonula adherens, what complex is it composed of?
Afadin-nectin complex
60
What are the catherine in the zonula adherens?
Cadherins (desmocollins + desmogleins)
61
What are the main transmembrane components of zonula adherens?
Cahderins (ca+ dependent)
62
What do cadherins form?
Homotypic calcium-dependent interactions in the EC space w/ cadherins of the neighboring cell
63
What is one of the main components in the folding of epithelial sheets into tubes, ducts for lateral specializations?
Cadherin-catenin-actin complex
64
In human disease, during the epithelial mesenchymal transitions, with mesenchymal, what is down regulated, what is up regulated?
Cdherins are down regulated Vimentin are upregulated
65
What are desmosomes?
Spot welds for cell to cell adhesion LATERAL SIDES SUPER STRONG!! (intermediate filaments)
66
What are the parts of the desmosomes?
Plakophilin -> desmoglein Pakoglobin-> desmocollin both to make desmoplakin
67
What are gap junctions?
Nexuses, gated channels that allow for ELECTRICAL + chemical communication between cells
68
What can pass through gap junctions?
LArge molecules CANNOT pass small molecules such as ions can
69
Where is the most important place for gap junctions?
Cardiac
70
What proteins are gap junctions formed out of?
Connexins | 6 monomers to form a connexion
71
What results in the closure of a gap junction?
High calcium concentration or low pH
72
What are basal attachments?
Hemi-desmosomes | Focal adhesions
73
What does PAS stain?
sugar molecules of proteoglycans
74
What is basal lamina composed of?
ECM in contact with epithelial cells (laminins, collagens, glycoproteins, proteoglycans)
75
What is the function of basal lamina?
Structural attachment for epithelial cells (Compartmentalization) COULD RESULT IN METASTASIS Of tumors
76
What are hemidesmosomes?
adhesive junctions attaching basal domain of epithelial cells to basal lamina intracellular plaque attaches
77
What is the basal lamina attached to the CT with?
Anchoring fibrils (typie VII collagen) loops around collagen III in the reticular lamina and the ECM molecules in the basal lamina
78
What is a focal adhesion?
Basal specialization Link between ACTIN cytoskeleton + ECM proteins via interns IMPORTANT for cell migration + wound healing
79
What are the major transmembrane proteins involved in focal adhesions?
Integrins

Histology and Embryology (5 decks)

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