Epithelial Tissue Flashcards
What is a tissue?
A tissue is a group (aggregate) of cells organised to perform one or more specific functions.
What are cells within tissue connected by?
specialized anchoring junctions
What is the function of specialized anchoring junctions?
Helps cells to:
- SENSE their SURROUNDING extracellular environment
- COMMUNICATE with each other.
What are the three types of junctions?
1) Tight junctions
2) Desmosomes
3) Gap junctions
What are tight junctions?
Impermeable junctions which prevent molecules from passing through the intercellular space.
What are desmosomes?
anchoring junctions which bind adjacent cells together and help them form an internal tension-reducing network of fibres.
What are gap junctions?
Communicating junctions which allow ions and small molecules to pass from one cell to the next for intracellular communication.
State the four types of tissue.
1) Connective Tissue
2) Epithelial Tissue
3) Muscle Tissue
4) Nervous Tissue
What is connective tissue?
Connective tissue UNDERLIES and SUPPORTS the other three basic tissues, both STRUCTURALLY and FUNCTIONALLY.
- connects, muscle, epithelial and nervous tissue to create an organ.
What is epithelial tissue?
Epithelial tissue covers body surfaces, lines body cavities, and forms glands.
What is muscle tissue?
Muscle tissue is made up of contractile cells and is responsible for movement.
What is nervous tissue?
Nerve tissue receives, transmits, and integrates information from outside and
inside the body to control the activities of the body.
- COGNITIVE FUNCTIONS
What is epithelial tissue?
Avascular tissue composed of cells that:
- cover exterior body surfaces
- line internal closed cavities (including the vascular system)
- line body tubes that communicate with the exterior (the alimentary, respiratory, and genitourinary tracts).
What does epithelium tissue form?
the secretory portion of glands and their ducts
PARENCHYMA CELLS
What else do epithelial cells do?
they act as receptors for the special senses.
What are the three principal characteristics of epithelium tissue?
1) always connected with cell junctions
2) attached to a basement membrane (a protein-polysaccharide-rich layer)
3) exhibit functional and morphologic polarity
What are the 3 domains of epithelial tissue?
- an apical domain (free surface), (different depending on body part) (eg. microvilli, cillia)
- a lateral domain (necessary to make cell junctions: connections (communication + nutrition sharing),
- a basal domain (attach the cell to the membrane).
What are the two main factors used to classify epithelium?
1) the number of cell layers
2) the shape of the surface cells
What are the different names given to epithelium, depending on the number of cell layers?
simple - one layer thick
Stratified - two or more cell layers
What are the different names given to epithelium, depending on the shape of the surface cells?
- SQUAMOUS: width > height; (remember by “squa”shed)
- CUBOIDAL: width = depth = height;
- COLUMNAR: height > width (remember by “column”ar)
What is keratin?
The protein found in the skin, which makes the skin waterproof.
Keratin gives the cell protection and dehydration.
How else can Stratified Squamous Epithelium be characterized?
KERATINIZED and NON-KERATINIZED.
What does it mean for a cell to be “keratinized”?
When cells in the surface layers of stratified squamous epithelium lack nuclei and have increased keratin in their cytoplasm, the epithelium.
LACK NUCLEI, and are FILLED WITH KERATIN.
What is ‘pseudostratified epithelium’?
Epithelium which appears stratified, although some of the cells do not reach the free surface.
All epithelium cells rest on the basement membrane and it is actually a simple epithelium.
