Epithelium Flashcards

1
Q

Parenchyma-active portion

A

fxnal
epithelial portion of organs
cells of an organ that provide fxn (hepatocyte)

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2
Q

Stroma-organization aspect

A

supporting CT of organ

CT serves as support, structure and protection of epithelial cells of the organ

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3
Q

Fxns of Epithelium

A

Covering/lining surfaces-skin, mucus membranes, respiratory tract, blood vessels
Absorption-intestines
Secretion-glands (salivary, intestinal, endocrine)
Sensation- neuroepithelium
Contractility- myoepithelium of sweat, salivary, mammary glands

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4
Q

Types of Epithelium: Shape

A

Squamous
Cuboidal
Columnar

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5
Q

Types of Epithelium: Number of layers

A

Simple
Stratified
Pseudostratified

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6
Q

Types of Epithelium: Specializations

A

Cilia
Microvilli
Goblet cells
Kertinization

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7
Q

Types of Epithelium: Fxn

A

Covering epithelia
Glandular epithelia
Secretory cells

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8
Q

Structure of Epithelium

A

All epithelial cells rest on a ECM called basal lamina (basement membrane)

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9
Q

Basal Lamina

A

Separates epithelium from support tissues (CT beneath)

Identifies orientation of cells above

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10
Q

Fxn of basal lamina

A
  • Supports the epithelial cells above
  • Acts as a diffusion barrier w/pores that are semi-permeable
  • Controls cell organization and differentiation
  • Pathway for cell migration during development and healing
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11
Q

Basal Lamina Components

A

Type IV collagen, laminin, heparan sulfate, fibronectin, CHO

—Composition of the basal lamina varies among tissue types based on the fxn of the particular tissues

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12
Q

Simple Squamous

A

Lungs
Lining of vessels
Serous lining of cavities
Facilitate mvmt of viscera; Active & Passive transport of substances

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13
Q

Simple Cuboidal

A

Covering of ovary, thyroid gland, kidney
Covering, secretion
Molecule Transport: active & passive

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14
Q

Simple Columnar

A

Lining of intestine, gall bladder

Protection, lubrication, absorption, secretion

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15
Q

Pseudo-stratified Columnar/Cuboidal

A

Lining of trachea, bronchi, nasal cavity, ducts of male repro.
Protection, secretion,absorption, cilia-mediated transport (trap air-borne particles)
Nuceli are at different levels–cilia;goblet cells

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16
Q

Keratinized: stratified squamous

A

Epidermis-multiple layers of squamous cells
Protection against friction, prevents water loss (dehydration)
no nuclei–deepest layer cuboidal shaped

17
Q

Non-keratinized: stratified

A

Mouth, esophagus, vagina, anal canal
Protection-areas of repeated forces/friction, secretion, prevents water loss
nuceli present

18
Q

Cuboidal: stratified

A

Sweat glands, ovarian follicles

Protection, secretion

19
Q

Transitional: stratified

A

Bladder, ureters

Protection, distensibility

20
Q

Columnar: stratified

A

Conjunctiva of eyes

Protection–mucus secreting

21
Q

Goblet Cells

A
  • Mucus secreting cells of epithelial tissues

- Found in intestinal and respiratory tracts

22
Q

Facet cells

A

change shape according to degree of bladder distention (cuboidal to squamous (closer to surface))

23
Q

Epithelial Cells: Innervation

A

Rich supply of capillary blood and sensory nerve endings from nerve plexuses in the CT (lamina propria-basement membrane)

24
Q

Renewal of Epithelial Cells

A

renewed continuously by means of mitotic activity

Rate of renewal is variable

25
Q

Rate of renewal rapid vs slow

A

Rapid: intestinal epithelial cells replaced each week; skin replaced in a month
Slow: liver and pancreas (monthS)

26
Q

Communicating Jxns= Gap Jxns

A

control passage of chemical and electrical signals from cell to cell
allow easy exchange of ions and small molecules–and pass b/w ells w/o reaching the extracellular fluid
IMPORTANT FOR APs to be coordinated, synchronized

27
Q

Occluding Jxns=tight jxns

A

seals cells together in a sheet-like formation

prevents mvmt of molecules b/w cells

28
Q

Anchoring Jxns

A

Desmosomes; Hemidesmosomes

-Attach cells to other cells or to extracellular matrix

29
Q

Gap Jxns Characteristics

A

Connexon
Permeability of the gap is controlled by individual connexins
Cells are able to control permeability of these jxns
Most wide spread cell jxns

30
Q

Connexon

A

pair of 6-protein connexons span lipid bilayer of adjacent cells
each protein of connexon is called CONNEXIN

31
Q

Tight Jxns-Occulding Jxns Structure and Fxn

A

Jxn forms a “band” completely encircling adjacent cells
Membranes “fuse” preventing material from moving b/w cells
Main fxn is to prevent diffusion b/w cells

32
Q

Why are tight jxns important in epithelial tissues

A

Skin-provides waterproof barrier

GI tract-prevents molecules from moving out of the gut lumen b/w nutrient absorbing cells

33
Q

Anchoring Jxns-Desmosomes

A

Serve as anchoring jxn to bind cells together
Widely distributed in animal tissues
Attachment sites for intermediate filaments

34
Q

Make-up of Desmosomes

A
  • intracellular attachment protein that connects desmosome to intermediate filament in cytoplasm
  • transmembrane linker protein (cadherin)
35
Q

Hemidesmosomes

A

bind cells to basal lamina