Epithelial Tissue Flashcards
What is the structure/characteristics of epithelial tissue?
Thin tissues that cover all exposed surfaces of the body.
Cellularity- closely bound cells, ECM
Avascularity- lack of blood vessels
Regeneration- cellular division of stem cells
*Higher rates of cell division/replacement
Polarity- apical/basal/lateral surfaces
Avascularity
The condition of having no blood vessels or blood flow
Apical surface
The top side of the cell facing the exposed surface, lumen, or environment
Basal surface
The bottom side of a cell attached to the basement membrane
Basement membrane
A thin membrane separating epithelial tissue from underlying tissue.
Made of basal lamina and reticular lamina.
Basal lamina
The superficial layer of the basement membrane
Reticular lamina
The deep layer of the basement membrane
Lateral surface
The side of a cell where cellular junctions are commonly found
Germinative (basale) cells
Cells that are actively dividing to regenerate lost or damaged surface cells
What are the functions of epithelial tissue?
Internal/external protection from abrasion, dehydration, and chemical/biological destruction.
Control permeability through absorption, exchange, secretion, excretion, filtration
Secretion (glandular cells)
Sensation (neuroepithelium) through smell, taste, vision, hearing
Neuroepithelium
Specialized epithelia that function as receptors for special senses (smell, taste, vision, hearing)
Where is epithelial tissue located?
Faces exposed surfaces or lumens,
Lines internal passageways, canals, chambers, cavities, ducts,
Forms glands
Glandular (gland) cells
Cells that produce secretions.
Can be scattered among other cell types or make up most/all of the epithelia
What are the two types of epithelial tissue?
Covering and lining epithelium, and glandular epithelium
Covering and lining epithelium
Epithelia that cover or line internal/external surfaces and lumens
Lumen
The cavity of a tubular organ
Glandular epithelium
Epithelia that form glands
Endocrine glands
Ductless glands that secrete hormones into the bloodstream
Ex. Pituitary gland, thyroid gland
Exocrine glands
Glands with ducts that secrete materials from the gland to the surface
Merocrine secretion
The most common type of secretion in which the cell remains intact and is released through exocytosis
What are examples of merocrine secretion?
Sweat glands, salivary glands, exocrine glands of the pancreas
Apocrine secretion
A type of secretion produced in the Golgi apparatus in which a portion of the cell pinches off and breaks down
What is an example of apocrine secretion?
Mammary glands
Holocrine secretion
A type of secretion in which the cell bursts
What is an example of holocrine secretion?
Sebaceous glands
Unicellular glands
Glands made up of independent, scattered gland cells among the epithelia
What is the only unicellular exocrine gland?
Goblet cells
Multicellular glands
Glands with multiple cells named by their shapes
If the duct of a gland is undivided, what do we call it?
Simple
If the duct of a gland is divided, what do we call it?
Compound
If the shape of the secretory portion of a gland is tube-like, what do we call it?
Tubular
If the shape of the secretory portion of a gland is round, what do we call it?
Alveolar or acinar
If there are several secretory areas sharing a single duct, what do we call it?
Branched
What is an example of a simple coiled tubular gland?
Merocrine sweat glands
What is an example of a simple branched alveolar gland?
Sebaceous glands
What is an example of a compound alveolar gland?
Mammary glands
What is an example of a compound tubuloalveolar gland?
Salivary glands, glands of respiratory passages, pancreas
Where is simple columnar epithelium ciliated?
Bronchioles of lungs, auditory tubes, uterine tubes, uterus.
Where is simple columnar epithelium non-ciliated?
Lining of stomach, intestine, gallbladder
Where is stratified squamous epithelium nonkeratinized?
Lining of: mouth, throat, esophagus, rectum, anus, vagina
Moist areas
Where is stratified squamous epithelium keratinized?
Skin surface
Dry areas
Where is pseudostratified columnar ciliated?
Trachea, bronchi of lungs, larynx, nasal cavity, auditory tubes
Cilia
Hair-like projections that aid in movement
Microvilli
Finger-like projections that add surface area to a cell
What is the function of simple squamous epithelium?
Reduce friction, control vessel permeability, absorption, secretion
What is the function of simple cuboidal epithelium?
Protection, secretion, absorption
What is the function of simple columnar epithelium?
Protection, absorption, secretion
What is the function of pseudostratified columnar epithelium?
Protection, secretion, move mucous with cilia
What is the function of stratified cuboidal epithelium?
Protection, absorption, secretion
What is the function of stratified columnar epithelium?
Protection
What is the function of transitional epithelium?
Expansion and recoil after stretching
What is the function of stratified squamous epithelium? (Keratonized or non)
Physical protection against abrasion/pathogens/chemical attacks
