Epithelial Tissues Flashcards
What are the four types of tissues and their general function?
Connective tissue: support
Epithelial tissue: covering
Nervous tissue: control
Muscle tissue: movement
What does the epithelium do?
It covers or lines every body surface and body cavity
What is the epithelium composed of?
One or two layers of closely packed cells between two compartments.
What are the characteristics of epithelial tissues?
- Cellularity
- Polarity (apical, basal, lateral)
- Attachment
- Innervation
- High regeneration capacity
What is cellularity?
Epithelial tissues are almost entirely composed of cells (with some extra cellular matrix and other structures)
What is polarity?
Epithelial tissues have specific top and bottom:
Apical: exposed to external environment or internal body space
Lateral: connected by intercellular junctions
Basal: connected to the underlying connective tissues
What is attachment?
Basal surface is bound to basement membrane
What is avascularity?
No blood vessels, receives nutrients across apical surface or through diffusion.
What is innervation?
Lots of nerve endings
What is high regeneration capacity?
Epithelial cells are frequently damaged or lost to abrasion, so they are replaced quickly
What are the functions of epithelial tissues?
Physical protection: protects exposed and internal surfaces from dehydration, abrasion and destruction.
Selective permeability: act as gatekeepers to let some substances in and keep others out.
Sensation: sense changes in the environment
Secretion: some contain glands that release sweat, scents and hormones etc.
