Lecture 3: Histology Flashcards
what are the 4 types of tissues?
- connective
- epithelial
- muscle
- nervous
T or F: Epithelial tissue varies in structure and function
true
what are the 6 characteristics of epithelial tissues?
- Form surface-parallel sheets
- Rest on basement membrane
- Sheet, and individual cells, are polarized.
- Cells tightly apposed to each other
- Avascular
- Dynamic
what are the 8 functions of epithelial tissue?
- Protection
- Secretion
- Absorption
- Trans-cellular transport
- Parallel transport
- Selective barrier
- Sensory (innervation)
- Contraction
free – attached
luminal – abluminal
what are the different epithelial classifications?
Number of layers
•Simple
•Stratified •Pseudostratified
Cell shape
•Squamous
•Cuboidal
•Columnar
Other
•Transitional
describe what simple squamous epithelium looks like
Flat, scale-like cells
what type of epithelium lines the cortex of the kidney, facilitates rapid diffusion,
filtration?
simple squamous epithelium
describe what simple cuboidal epithelium looks like
Cells appear to look like cubes when viewed laterally
Retinal Pigment Epithelium (RPE) is what type of epithelium
simple cuboidal
describe what simple columnar epithelium looks like
Cells appear taller than wide
what is the function of a simple columnar epithelium?
to protect
what epithelium can be innervated to provide sensory input to the cornea?
simple columnar epithelium
describe what pseudostratified epithelium looks like
Appears greater than one cell thick, but all cells make contact with the basement membrane
describe stratified squamous epithelium
Appears greater than one cell thick, but all cells make contact with the basement membrane
where is stratified squamous epithelium
Found on surfaces where friction occurs
what type of epithelium is the stratified corneal epithelium?
stratified squamous epithelium
how thick is stratified corneal epithelium?
(50 u)
Stratified epithelium is named from what layer
the superficial layer
are the stratified squamous surface cells keratinized or non-keratinized
non-keratinized squamous cells
how thick are wing cells?
20 u
define the basal cell layer of the stratified corneal epithelium
(single layer
columnar cells, 8-10 u)
what are two types of simple squamous epithelium and what do they line?
Endothelium
lines heart, blood vessels, and lymphatic vessels.
Mesothelium
lines body cavities and covers all organs that project into these cavities.
what does keratinization protect against
Keratinization protects against abrasion, desiccation and microbial invasion
what is the clinical correlation to the keratinized epithelium?
Ocular cicatricial pemphigoid (OCP)
what is the space between two cells in angstroms?
~150 Angstroms
what are two specializations of the apical surface?
- microvilli
- cilia
what are the three specializations of the lateral surface?
- Occluding junctions
- Adhering junctions
- Communicating
what are two specializations of the basal surface?
- Basal lamina
- Basal striations
The microvillus increases what?
the surface area of a cell
The number and shape of the cell’s microvilli correlate with its what?
absorptive capacity.
Beating cilia move particulates parallel to what?
to the cell surface
what are the 3 intercellular junctions
- occluding
- adhering
- communicating
what is an example of an occluding intercellular junction?
- zonula occludens
what is are 3 examples of adhering intercellular junctions?
- Zonula adherens
- Desmosome
- Hemidesmosome
what is an example of a communicating intercellular junction?
Gap junction
what forms complete encircling girdles around the cell?
- zonula occludens (tight junctions)
what are the 3 functions of zonula occludens (tight junction)?
- Obliterates intercellular space, preventing passage of material between adjacent cells
- Points of attachment are between transmembrane proteins (occludens) located along ridge-like elevations
- Separates apical membrane region from basolateral membrane region
macula adheres are what?
desmosomes
Transmembrane proteins (cadherins) link what?
the cytoskeletal elements of adjacent cells.
Hemidesmosome attach what?
Hemidesmosome attach epithelial cell to the basal lamina
Transmembrane proteins of the integrin family link what?
the hemidesmosome to the ECM (extra cellular matrix)
what are macula communicans?
gap junctions
gap junctions allow for what?
intercellular communication and
electrical coupling of cells
do gap junctions have a low or high resistance pathway for current flow?
low resistance pathway for current flow
what allows for the fast spread of electric activity throughout the organ (smooth muscle contraction)
gap junctions
what are the 5 functions of the basement membrane?
- Structural attachment; flexible and firm
- Compartmentalization; separation of tissues
- Filtration, both physical and polyanionic
- Tissue scaffolding
- Regulation and signaling (in morphogenesis, development, wound healing)
what do exocrine glands do?
Secrete via duct or release product directly onto surface of an epithelium
what do endocrine glands do?
Produce hormones Secrete contents into underlying connective tissue or general circulation
what is adenocarcinoma?
malignant glandular epithelial cells
are goblet cells unicellular or multicellular?
unicellular
