Module 1 (Epithelium) Flashcards
What is epithelium
Basic tissue composed of closely apposed cells with little to no intervening intercellular substance
What are the two types of epithelium
Covering and glandular
What is covering epithelium
Cells that cover the external and internal surfaces
What is glandular epithelium
Cells that produce and secrete hormones
What is cellularity
Adjacent epithelial cells joined by specialized surfaces
What are the 4 types of junctions
Tight junctions, adhering junctions, desmosomes, and gap junctions
What is polarity
When an epithelial cell has an exposed surface that faces the exterior of the body or internal space
A basal surface where it is attached to the underlying tissue
What is attachment
Epithelial cells rest on and are attached to the basal lamina (basement membrane)
What is avascularity
Epithelial tissues have no direct blood supply so they receive nutrients from the blood vessels in the underlying tissue
What is regeneration
When epithelial cells are renewed continuously
What are the functions of epithelium
Support and protection
Permeability
Sensation
Secretion
Support and protection (Epithelium)
Covers and lines external and internal surfaces of the body protecting underlying tissue from injury, pathogens and dehydration
Permeability
Allows for substances to be absorbed into the body
Sensation
Some cells contain specialized cells that detect sensory stimuli
Secretion
Some cells are specialized to secrete specific substances (skin secretes lubrications oil)
Two ways cells can be organized
Simple or stratified
How many cell layers do simple cells have
One
How many cell layers do stratified cells have
Two or more
Only the deepest layer is in contact with the basal lamina
What are the three cell shapes
Squamous
Cuboidal
Columnar
Characteristics of squamous
Flat (thin), wide, somewhat irregularly shaped
Characteristics of cuboidal
About the same size on all sides, the nucleus is centrally located
Characteristics of columnar
Taller than they are wide, nucleus is oval and located in the basal region of cell
Simple squamous
Single layer of flattened cells
Where can simple squamous be found
In the lining of blood vessels
Why should blood vessels have a thin barrier
They transport materials to and from cells and the thin barrier allows for rapid exchange
Simple cuboidal
Single layer of cube cells
Where can simple cuboidal cells be found
In the lining of some glands
Simple columnar
Single layer of column shaped cells
Where can simple columnar cells be found
In the lining of the gastrointestinal tract
Why is it useful for cells to be simple columnar in the lining of the gastrointestinal tract
Allows for rapid secretion or absorption of material
Stratified squamous
Multiple layers of flat cells
Where can stratified squamous cells be found
The most superficial layer of skin to protect deeper structures from abrasion and damage
Stratified cuboidal
Multiple layers of cube shaped cells
Where are stratified cuboidal cells found
In some ducts of glands
Function of stratified cuboidal cells
Secretion, protection, and strengthening the walls of ducts
Stratified columnar
Multiple layers of column shaped cells
Where can stratified columnar cells be found
Rare in the human body but can be found in male urethra
Functions of stratified columnar cells
Protection and secretion
Transitional epithelium
Multiple layers of epithelial cells that allow for stretching
Shape of transitional epithelium
Vary in shape, depending on whether the tissue is stretched or relaxed
Where can transitional epithelium be found
Lines the ureters and proximal end of the urethra (near the bladder)
What happens to transitional epithelium in the urinary bladder
Able to change shapes as urine accumulates in the bladder
Pseudostratified (ciliated columnar)
Single layer of cells and has its cell nuclei positioned in a manner suggestive of stratified epithelium
What does the cilia on the surface of pseudostratified epithelium help with
Helps to move mucous
Where can pseudostratified epithelium be found
Throughout most of the respiratory tract
