General Anatomy (Epithelial Tissue) Flashcards
What are the four types of tissues?
- Connective tissue
- Epithelial tissue
- muscle tissue
- Nervous tissue
What is the epithelial tissue?
- Epithelial tissue covers or lines every body surface and body cavity
- Epithelial is composed of one or more layers of closely packed cells between two compartments
What are the characteristics of epithelial tissue?
- Cellularity - composed almost entirely of cells
- polarity - has specific top and bottom
- attachment - basal surface bound to basement membrane
- avascularity - no blood vessels, receive nutrients across apical surface or by diffusion
- Innervation - lots of nerve endings
- high regeneration capacity - epithelial cells are frequently damaged or lost to abrasion, so they are replaced quickly
What are the functions of epithelial tissue?
- physical protection - protect exposed and internal surfaces from dehydration, abrasion, destruction
- Selective permeability - act as gatekeepers to let some substances in and keep others out
- sensation - sense changes in the environment
What is basement layer?
Is extracellular layer between epithelium and connective tissue
What is a hemidesmosomes?
In some epithelial tissue, basal cells anchored to basement membrane with junctions called hemidesmosomes.
What are intercellular junctions?
- Junctions between cells in epithelium
What are tight junctions?
- anchor cells to each other
- prevent substances from passing between cells
- materials must move through cells, or are blocked from moving past cells
- found in intestinal lining
- Adhering junctions often deep to tight junctions
- form all the way around a cell
- support apical surface
- allows passage between cells below apical surface
What is the cell-cell attachment?
- Desmosomes attach cells yo each other
- bind epithelium together
- bind muscle cells
- resist shear forces
What is cell-cell communicating attachment?
- Gap junctions tunnel between two plasma membrane
- found in muscles
- Enables sharing of ions and proteins
- enables fast communication between cells
What are the two different type of epithelial tissue?
Simple - one cell layer thick
Stratified - more than two cell layers thick
What are the three different types of epithelial tissue?
Squamous - flattened
Cuboidal - cube shaped or roundish
Columnar - long and thin like a column
What is a microvilli?
- they are cylindrical, membrane-bound, finger like cytoplasmic projections emanating from the apical surface of absorptive cells
- found in the intestinal absorptive cells and the kidney proximal tubule cells
What is stereocilia?
- long, non-motile processes
- longer branched microvilli
- do not contain microtubules
- function is absorbing
- found lining part of male reproductive tract
What is a cilia?
- Cylindrical, motile structures that produce rapid back and forth movement in one direction
- contains central and peripheral microtubules surrounded by cell membrane
- permits movement of fluid or particulate matter over epithelial surface
- ATP is a source of energy for ciliary motion
- found in respiratory tract and uterine tube
What is the simple squamous epithelium?
Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm, the simplest of the epithelia
What is the function of the simple squamous epithelium?
Allows passage of materials by diffusion and filtration in sites where protection is not important, secretes lubricating substances in serosae
What is the location of the simple squamous epithelium?
- kidney glomeruli
- air sacs of lungs
- lining of heart
- blood vessels
- lymphatic vessels
- lining of ventral body cavity