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MCM > ILS6-epithelial tissue > Flashcards

ILS6-epithelial tissue Flashcards

1
Q

Functions of the Epithelial Tissue (7)

A
  1. Protection or barrier (epithelial cells of the
    skin)(ILS-4 HDM)
  2. Absorption (epithelium in liver, intestines, and
    lungs)
  3. Secretion (epithelial tissue in glands secrete
    enzymes, hormones, and fluids)
  4. Excretion and transport (epithelial tissue in the
    kidney and sweat glands)
  5. Filtration (epithelium in the kidney and
    respiratory system)
  6. Contractility (Myoepithelial cells)
  7. Sensory reception (Taste buds of the tongue,
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2
Q

what is the basement membrane (BM) of epithelial tissue compossed of?

A

basal lamina + reticular lamina

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3
Q

basal lamina contains____

A

a thin meshwork of type IV collagen (ILS-7) and laminin associated with proteoglycans and glycoproteins, secreted by epithelial
cells

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4
Q

reticular lamina contains ____

A

type III collagen and anchoring fibrils of type
VII collagen, secreted by fibroblasts

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5
Q

function of Basement membrane

A
  • attach epithelia to connective tissue
  • provide a guide or scaffold during tissue regeneration after injury
  • compartmentalize epithelial cells from other tissues
  • filter substances passing from connective tissue into epithelia
  • Prevent tumor metastasis
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6
Q

below the Basement membrane you find the _____

A

Lamina propria is a thin, irregular connective tissue

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7
Q

special function of basement membrane in kidney

A

filter

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8
Q

Microvilli

A

short membrane projections with cores of actin filaments
* increase epithelial cells’ apical surface area for absorption (intestine)

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9
Q
  • Stereocilia
A
  • Long microvilli with specialized mechanosensory functions in cells of the
    inner ear and for absorption in tissues of the male reproductive tract
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10
Q

Cilia

A
  • larger projecting structures
  • has a well-organized core of microtubules (in a 9 + 2 arrangement called
    the axoneme) in which restricted, dynein-based sliding of microtubules
    causes ciliary movement that propels material along an epithelial surface
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11
Q

The internal structure of microvilli

A

The internal structure of microvilli contains a core of
actin that is cross-linked by actin-bundling proteins

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12
Q

what are the Actin-bundling proteins:

A

Actin-bundling proteins: fascin, espin, and fimbrin FEF

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13
Q

what anchors the actin of microvilli to the membrane

A

tip of head is anchored by villin

Myosin I: binds the actin to the plasma membrane of the microvillus
* Myosin II and tropomyosin of the terminal web (TW)
explain its contractile ability
* The TW is composed of actin filaments stabilized
by spectrin, which also anchors the TW to the apical cellmembrane

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14
Q

stereocilia

A

immotile microvilli

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15
Q

where is stereocilia found ?

A
  • Limited to the epididymis, the proximal part of
    the ductus deferens of the male reproductive
    system, and the sensory (hair) cells of the
    inner ear
  • Stereocilia of the genital ducts are extremely
    long processes that extend from the apical
    surface of the cell and facilitate absorption
  • Stereocilia of the sensory epithelium of the
    ear are sensitive to mechanical vibration and
    serve as sensory mechanoreceptors
  • Stereocilia can be easily damaged by
    overstimulation, so they have a molecular
    mechanism to continuously renew their structure
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16
Q

stereocilia of epididymis are ______

A

long

17
Q

stereocilia are anchored to the memebrane by

A

Ezrin (myosin 1 and 1 in microvilli)

no villin

18
Q

cilia

different types of cilia

A

Cilia
* Hair-like extensions of the apical plasma membrane containing an axoneme

19
Q

different types of cilia

A
  • Motile cilia are on the apical side of
    epithelial cells
  • Primary cilia (monocilia) are solitary
    immotile projections on almost all
    eukaryotic cells
  • Nodal cilia are in the embryo on the
    bilaminar embryonic disc at the time of
    gastrulation
20
Q

Motile cilia

A

Motile cilia are on the apical side of
epithelial cells

21
Q
  • Primary cilia (monocilia)
A

are solitary
immotile projections on almost all
eukaryotic cells

-function as chemosensors, osmosensors,
and mechanic sensors
- mediate light sensation, odorant, and
sound perception

22
Q
  • Nodal cilia
A

_____are in the embryo on the
bilaminar embryonic disc at the time of gastrulation

  • play an important role in early embryonic development
  • perform clockwise rotational movement
23
Q

what is the structure of Cilia?

A

Axoneme- microtubule based structure, extends from the basal body

a centriole-derived, microtubule-organizing center (MTOC) located in
the apical region of a ciliated cell

microvili and cilia look similar under microscope

  • ciliary apparatus= basal bodies + basal body–associated structures
  • Motile cilia and their counterparts, flagella, possess a typical 9 + 2
    axonemal organization with microtubule-associated motor proteins
    generating forces needed to induce motility
24
Q

Epithelial intercellular junctions
* Lateral cell-to-cell junctions (3)

A

Tight or occluding junctions:

Adherent junctions or desmosomes

Gap or communicating junctions

25
Q

Tight or occluding junctions:

A

interacting
transmembrane proteins (claudin and occludin)

prevents intracellular passage

26
Q

Adherent junction or desmosomes

A

formed by the
cadherin, strong sttachement between epithelium

may form zonula adherens encircling epithelial cells just below
their tight junctions and attach indirectly to actin filaments or
scattered, spot-like attachment sites
called desmosomes or maculae adherens, which attach
to keratin* intermediate filaments

27
Q

Gap or communicating junctions

A

points of cell contact
where both plasma membranes have hexameric complexes
of transmembrane connexons, each forming a channel
(pore) allowing passage of small molecules from one cell to
the other

28
Q

epithelial Basal surface junction

A

Basal surface junction
* Hemidesmosomes composed of transmembrane integrins
attach cells to proteins of the basal lamina

29
Q

Tight junctions (TJ) fuction

A

Allow epithelial cells to function as a barrier
* Form the primary paracellular diffusion
barrier between adjacent cells
* Limit the movement of ions, water, and other
macromolecules through the intercellular
space
* Act as fences to prevent the migration of
lipids and specialized membrane proteins
between the apical and lateral surfaces
* Maintain cell polarity and integrity of the
apical and lateral surfaces
* Recruit signaling molecules to the cell
surface and link them to the actin
filaments of the cell cytoskeleton

30
Q

Helicobacter pylori damages

A

binds the extracellular domains of tight-junction proteins in cells
of the stomach and inserts a protein into these cells, which
targets (Zona Occludin-1) ZO-1 and disrupts signaling from the
junction

leads to gastric ulcers

31
Q

Pemphigus vulgaris

A

autoimmune skin disorder where IgG
targeting desmoglein leads to dissolution of the desmosomes, fluid
accumulation, and epidermal cells detach
– Symptoms: painful blisters and sores in the mouth, skin blisters

– Treatment: corticosteroids, immune suppressants,
plasmapheresis or immunoglobulins

32
Q

Bullous Pemphigoid:

A

rare autoimmune skin disorder where IgG
(antibody) targets hemidesmosomes, specifically type XVII collagen,
causing the epidermis to detach from the basement membrane,
causing blistering

33
Q

gap junctions

A

consists of an accumulation of
transmembrane channels or pores
* present in epithelia, smooth and
cardiac muscle, and nerves
* permit the direct passage of
signaling molecules from one cell to
another
* important in tissues in which the
activity of adjacent cells must be
coordinated, such as epithelia
* engaged in fluid, electrolyte, small
metabolites transport, vascular and
intestinal smooth muscle, and heart
muscle

34
Q

what microorganism damages the tight junction s

A

Clostridium perfringes
-its enterotoxin binds to claudin of tight junction and messes up its maintence

causes fliud loss

Helicobacter Pylori,
target the Zona occludin and disrupt the signaling from the junction, leads to gastric ulcers

35
Q
A

MCM (13 decks)

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