Epithelial Tissue Flashcards Preview

Histology > Epithelial Tissue > Flashcards

Flashcards in Epithelial Tissue Deck (21):
1

Junctions

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A=Tight Junction

B=Adherens

C=Desmosome

D=Gap Junction

E=Hemidesmosome

2

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Simple Squamous

Function: allows passage of materials by diffusion and filtration, secretes lubricating substances

Location: Lining of blood vessels/lymphatics, alveoli, renal glomeruli, heart; serous lining of cavities (mesothelium)

3

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Simple Cuboidal

Function: Secretion and absorption

Location: Renal tubules, ducts and gland

4

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Simple Columnar

Function: protection, lubrication, absorption, secretion

Location: lining of intestine, gallbladder, female reproductive tract

5

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Stratified Squamous

Function: protection, secretion, prevention of fluid loss

Location: skin, mouth, esophagus, larynx, vagina, anus

6

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Stratified Cuboidal

Function: protection, secretion

Location (rare): sweat glands, mammary glands, testes, developing ovarian follicle

7

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Transitional

Structure: top layer made up of dome shaped cells with specialized membrane that allows them to withstand hypertonic effects of urine and protect underlying cells from toxins; cells can adjust their relationships with each other as urinary bladder fills and wall is distended

Function: protection,distensibility

Location: Bladder, ureters, renal calyces

8

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Stratified Columnar

Function: protection, secretion

Location (rare): parts of male urethra, some glands

9

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Pseudostratified

Function: protection, secretion, cilia-mediated transport of mucous and trapped particles

Location: lining of trachea, bronchi, nasal cavity

10

Endocrine or Exocrine Gland?

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Exocrine (duct)

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Endocrine or Exocrine Gland?

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Endocrine

12

Tight Junction

  • function like the plastic that holds 6 pack of beer together
  • Found in epithelia, opposing cell membranes held in tight contact by transmembrane adhesive proteins (claudin ,occludin, junctional adhesion molecule)

    •Creates a physical/chemical barrier to control paracellular movement of substances

    •Also helps define and maintain separation between apical and basal areas of cell membrane to maintain cell polarity

13

Epithelial Tissue Function

  • Protection
  • Transport of nutrients, gases, waste material
  • Screte lubricating fluid (serosal surfaces)
  • Make up functional tissues of organs and are key elements of many glands
  • Specialized epithelail cells serve as sensory receptors

 

14

Adherens Junctions

•holds opposing cell membranes together (with thin sliver of intercellular space)

•The intercellular space is bridged by cadherins

•Cadherins attach to cytoplasmic proteins (catenins) which in turn attach to cytoskeletal components (actin filaments, microtubules)

•These transmembrane protein complexes interact with signaling molecules, including tumor suppressor molecules

–Play a role in regulating cell-to-cell contact

(essential for morphogenesis, remodeling of

tissue/organs, controlled proliferation of cells)

15

Desomosomes

  • Anchoring junctions that reinforce cellular adhesion
  • Desmosomal cadherins attach to intermediate filaments in cytoskeleton for additional support
  • Prominent in tissues under mechanical stress
  • dysfunction of desmosoal cadherins associated with cell adhesion cardiomyopathy (arrythmogenic right ventricular dysplasia) blistering diseases (pemphigus vulgaris)

16

Gap Junctions

  • Clusters of intercellular channels that allow rapid transmission of electrical or chemical information from cell to cell
  • Intercellular gap spanned by channel forming transmembrane proteins
  • connexins form connexons, which aligh with neighboring connexons

17

Hemidesmosome

  • Integrin interacts with laminin to links intermediate filaments of cytoskeleton to extracellular basement membrane
  • integrin plays role in cell-cell communication

18

Basement Membrane

  • Macromolecules that bind hormones and other cell signaling molecules
  • semi permeable filter for substances coming to cell from underlying tissue
  • epithelial cells require contact with basement membrane for normal function and to establish polarity
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