This preview shows page 1. Sign up to view the full content.
Unformatted text preview: ody organs (such as the gut, the bladder, blood vessels etc.) Epithelial Tissues II • EPITHELIAL SHEETS comprise a barrier between the body and the environment (e.g., the intestinal epithelium separates fluid in the lumen of the gut [outside the body] from the blood - the skin is a second example) and rest upon a secreted layer of extracellular protein termed the basement membrane Structure and Function of Epithelia
• Comprise a barrier between the body and the environment
Any material entering or leaving the body must cross an epithelial layer • Epithelial cells are closely joined by tight junctions and exhibit absorptive and transport functions (for both solutes and fluids) Some epithelia are secretory (e.g., milk, mucus, digestive enzymes, hormones) or have been modified to form exocrine (e.g., sweat) glands Others are specialized for active uptake (e.g., intestinal epithelium, kidney epithelium) of ions and organic molecules Epithelial Polarity
• Epithelial cells display polarity (distinct inner and outer surfaces), which differ in both structure and function Apical surfaces face either the environment or the lumen These surfaces are These frequently ciliated or possess microvilli Basolateral surfaces face the blood Different proteins are Different expressed in apical and basolateral membranes Apical surface (lumen) Basolateral surface (blood) Connective Tissues
• Specialized for connecting, anchoring, cushioning, and support of other tissues
Include loose (ad...
View Full Document
This note was uploaded on 10/25/2010 for the course MUS 347 taught by Professor Mook during the Fall '08 term at ASU.
- Fall '08