Epithelial tissue covers body surfaces, lines many internal spaces, and forms much of the body's glandular tissue. Understanding its locations and shared features helps explain how it protects the body and controls the movement of substances.
Epithelial tissue forms sheets that cover surfaces exposed to the outside world and line many organs and passageways. Skin is one example, but the respiratory airways, digestive tract, and urinary and reproductive systems are also lined by epithelium. Epithelium also forms much of the body's glandular tissue.
All flashcards
What is epithelium?
A closely packed tissue that covers body surfaces, lines organs and passageways, and forms much of the glandular tissue.
What is endothelium?
The epithelial lining of blood vessels and lymphatic vessels.
What is epithelial polarity?
The structural and functional difference between a cell's apical surface, facing a space or exterior, and its basal surface, facing underlying tissues.
What forms the basement membrane?
The basal lamina, associated with the epithelium, and the reticular lamina, secreted by underlying connective tissue, together form the basement membrane.
Why are epithelia called avascular?
Blood vessels do not enter most epithelial tissues across the basement membrane, so nutrients reach cells by diffusion or absorption from nearby surfaces and tissues.
Quiz questions
In the airways, what do cilia move along the epithelial surface?Answer: Mucus containing trapped particles toward the throat.
What is the primary function of tight junctions between epithelial cells?Answer: They seal the space between cells and restrict passage through it.
Which feature distinguishes pseudostratified epithelium from truly stratified epithelium?Answer: All its cells contact the basal lamina, though some do not reach the surface.
How does transitional epithelium change as the urinary bladder fills?Answer: It stretches, its folds flatten, and its apical cells appear more squamous.
How do endocrine glands release hormones?Answer: They release hormones into interstitial fluid, which then carries them into the blood.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.