Flashcards in Epithelial Tissue Deck (11):
Name 4 characteristics of EPITHELIAL TISSUE.
1. The cells in EPITHELIAL TISSUE have polarity. Their apical surface is exposed and their basal surface is anchored to the underlying connective tissue.
2. They have layers of cells bound tightly together by cell junctions.
3. They are avascular, so there is no blood present. Exchange of nutrients, waste by diffusion.
4. They have a high rate of cell division to replace lost or damaged cells.
What are the 3 types of cell junctions?
1. Tight junctions
3. Gap junctions
Explain TIGHT JUNCTIONS.
TIGHT JUNCTIONS are made from interlocking membrane proteins fuse adjacent cell membranes and prevents molecules moving between cells. An example of this would be keeping the stomach acid from "eating" the surrounding tissues.
DESMOSOMES are made from transmembrane proteins reinforced by cytoskeleton which gives it a strong connection that resists stretching or twisting. An example is when a sunburn is peeling off and the skin comes off in sheets (so weirdly satisfying to do...).
Explain GAP JUNCTIONS.
GAP JUNCTIONS are made from channel proteins connecting cells and allowing the exchange of small molecules and ions. an example is the coordination of cilia beating in the trachea.
What are the 8 types of EPITHELIAL TISSUE?
1. SIMPLE SQUAMOUS
2. SIMPLE CUBOIDAL
3. SIMPLE COLUMNAR
4. STRATIFIED SQUAMOUS (non/keratinized)
5. STRATIFIED CUBOIDAL
6. STRATIFIED COLUMNAR
7. PSUEDOSTRATIFIED CILIATED COLUMNAR
Characteristics of SIMPLE SQUAMOUS.
SIMPLE = 1 layer
SQUAMOUS = Flat, thin cells, great for diffusion, not so great for protection...
These cells line protected areas and reduce the time and distance required for diffusion. The MESOTHELIUM lines body cavity and the ENDOTHELIUM lines heart, blood vessels, walls of alveoli, and capillaries.
Characteristics of SIMPLE CUBOIDAL.
SIMPLE = 1 layer
CUBOIDAL = Square-shaped which means more cytoplasm and therefore more absorption and secretion.
Can be found lining the kidney tubules, pancreatic ducts, salivary glands, and even forms some glands.
Characteristics of SIMPLE COLUMNAR.
SIMPLE = (You guessed it) 1 layer
COLUMNAR = Column-shaped, even more cytoplasm which mean even better secretion and absorption! YAY!
These babies form glands and line the stomach and intestine.
*Keep in mind that their nucleus and elongated and located near the basal surface.
Characteristics of STRATIFIED SQUAMOUS.
STRATIFIED = Many layers, which is good for protection, the more the merrier!
SQUAMOUS = Apical layer of cells is flat`