Histology Lecture (Epithelial Cells) Flashcards
Group of similar cells specialized in a common direction to perform a common function
Tissues
3 primitive germ
layers tissue is derived from
- ectoderm
- mesoderm
- endoderm
4 Primary Tissues
- Epithelial tissues
- Connective tissues
- Muscular tissues
- Nervous tissues
____________ is made up of ____________, closely arranged and strongly attached to each other that they have scanty intercellular substances.
- Epithelial Tissue
- Polyhedral cells compact
Epithelial Tissues are attached to ____________
extracellular matrix (ECM)
Is avascular or no blood vessels found among the cells.
Epithelial Tissue
This means there is no blood vessels found among the cells.
Avascular
If the Epithelial tissue is avascular, how and where does it get its nourishment?
Nourishment is conveyed through osmosis and
diffusion from blood vessels located at the tunica
propia
Covers the body surfaces and those found as sheets lining the organ cavities.
Epithelial Tissue
Epithelial Tissues are usually wet except where?
Epidermis of the skin
Some Epithelial tissues are arranged in the form of masses. Give 2 examples.
- Adrenal gland
- Parathyroid gland
Epithelial Tissue Cells are replaced through?
Mitosis
3 main functions of Epithelial Tissue.
- Absorption
- Secretion
- Covering
Epithelial Tissue Function: Absorption
Distribution: Small Intestine
Epithelial Tissue Function: Secretion
Distribution: Glands
Epithelial Tissue Function: Excretion
Distribution: Kidney Tubules
Epithelial Tissue Function: Protection
Distribution: Skin/Epidermis
Epithelial Tissue Function: Sensory Reception
Distribution: Neuroepithelium
Epithelial Tissue Function: Lubrication
Distribution: Sebaceous Glands
Epithelial Tissue Function: Reproduction
Distribution: Lining of the Ovary
Where all epithelial tissue cells are attached.
Basement Membrane/Basal Lamina
Provides anchorage for the cells.
Basement Membrane/Basal Lamina
Barrier limiting or regulating exchanges of macromolecules b/w CT and other tissues.
Basement Membrane/Basal Lamina
Components contribute to image of basement membrane
- Basal Lamina
- Reticular Fibers
- Ground Substances
2 layers of Basement Membrane
- Basal
- Reticular
Type of basement membrane that contains Type IV Collagen and Lamina.
Basal
Type of basement membrane that contains type III Collagen and Type VII Collagen.
Reticular
It provides support to the epithelium and vascularized CT bed.
Tunica Propia/Lamina Propia
T or F: All epithelia has tunica propia.
True
Structures Associated with Epithelial Tissues
- Basement Membrane/Basal Lamina
- Tunica Propia/Lamina Propia
2 Specialization of Epithelial Tissues
- Tendency to maintain excessive contact with
one another. - For cell attachment and communication.
In __________, it refers to the structural
and functional differences b/w 2 ends.
- Columnar Epithelium
- Polarity
Imaginary line passing through the
centrosome and center of the nucleus.
Cell Axis
Perpendicular to basal lamina.
Cell Axis
Made of feltwork of fine filaments
beneath the surface.
Terminal Web
Provide mechanical support for
ciliated or striated borders.
Terminal Web
In the “Tendency to maintain excessive contact with one another,” give 3 specializations.
- Polarity
- Cell Axis
- Terminal Web
Cell attachment and communication can be observed only by?
Electron Microscopy
Give 4 Juxta-luminal Junctional Complex
- Zonula Occludens/Tight Junctions
- Zonula Adherens/Intermediate Junctions
- Desmosomes/Macula Adherens
- Gap Junctions/Nexus
Most apical of the junctions.
Zonula Occludens/Tight Junctions
Junction encircle the cell.
Zonula Occludens/Tight Junctions
Adjoining cell converge and fused to close intercellular space
Zonula Occludens/Tight Junctions
Its outer leaflets of adjacent unit membrane are fused, giving rise to a local pentalaminar appearance.
Zonula Occludens/Tight Junctions
It has a mechanical role in maintenance of structural integrity of cells
Zonula Occludens/Tight Junctions
Serve as tight seal preventing flow of materials b/w epithelial cells (parallel pathway).
Zonula Occludens/Tight Junctions
Responsible for structure called terminal bar
Zonula Occludens/Tight Junctions
Extends around the entire perimeter of the cell. found at the apex of the cell.
Zonula Occludens/Tight Junctions
2 proteins in Zonula Occludens/TIght Junctions
- Claudin
- Occludin
Regions where adjacent cells are firmly held together.
Zonula Adherens/Intermediate Junctions
Where can Zonula Adherens/Intermediate Junctions can be found (4)?
Found b/w:
1. epithelial cells
2. fibroblast
3. smooth muscle cells
4. intercalated disc of cardiac muscles
Also responsible for terminal bar.
Zonula Adherens/Intermediate Junctions
Function of Zonula Adherens. Couples what?
Couples Actin
Protein of Zonula Adherens/Intermediate Junctions
- Cadherins
Adhering Junctions
- Zonula Adherens/Intermediate Junctions
- Desmosomes/Macula Adherens
- Hemidesmosomes
Impermeable Junctions
- Zonula Occludens/Tight Junctions
Communicating Junctions
- Gap Junctions/Nexus
Disk-like structure at the surface of 1 cell that is
match with identical structure at surface of
adjacent cell
Desmosomes/Macula Adherens
____________ is only present in stratified squamous epithelium attach the ends of short processes (erroneously interpreted as “___________”)
- Desmosomes/Macula Adherens
- Intracellular Bridges
Only function is as special adhesion of cells.
Desmosomes/Macula Adherens
2 protein of Desmosomes/Macula Adherens.
- Desmoglein
- Desmocollin
Function of Desmosomes/Macula Adherens. Couples what?
Couples Intermediate Filaments
Contact b/w certain epithelial cell and basal lamina.
Hemidesmosomes
Protein of Hemidesmosomes.
Integrin
Diseases when desmosomes are abnormal.
- Blistering Disease
- Bullous Disease
Where can Desmosomes can be found?
Stratified Epithelia of esophagus, mouth, and vagina.
Bipartite structures of opposing cell membranes.
Desmosomes/Macula Adherens
______________ can be mistaken for zonula occludens but _______________.
- Gap Junctions/Nexus
- opposing membrane are not fused
____________ can occur almost anywhere along ____________ of most epithelial cells.
- Gap Junctions/Nexus
- Lateral membranes
Gap Junctions are only absent in?
- skeletal muscle
- blood cells
Well developed in tissues where cells are
electrically coupled
Gap Junctions/Nexus
Gap junctions are well developed in tissues where cells are electrically coupled:
Give 2 examples.
- cardiac cells
- smooth muscle cells
Protein of Gap Junctions/Macula Adherens.
Connexin
It aids in the synchronization of cells.
example: the pumping action of cardiac cells.
Gap Junctions/Nexus