Summary chapter 4

Epithelial Tissue


 Parenchyma the functional tissue of an organ as distinguished from the connective and
supporting tissue
 Stroma, the cells of which have a supporting role in the organ (Except in the brain and
spinal cord, the stroma is always connective tissue)




 Epithelia cells (thin layer of ECM) line cavities of organs and cover the body surface with 3
main functions:
1. Secretion (glands)
2. Absorption (intestinal lining)
3. Covering, lining and protecting surfaces (epidermis)
 Specific cells of certain epithelia may be contractile (myo-epithelial cells) or specialized
sensory cells, such as those of taste buds or the olfactory epithelium.
 Can be of 3 sizes and shapes:
 Columnar
 Cuboidal
 Squamous
 Most epithelia rest on connective tissue that contains
microvasculature bringing nutrients and O2
 The connective tissue that underlies the epithelia lining the
organs of the digestive, respiratory, and urinary systems is called
the lamina Propria.
 Papillae: evaginations between epithelium and connective tissue
 Epithelial and adjacent connective
to reduce friction (skin or tongue)
tissue
 Nutrients for epithelial cells must
diffuse across the basement membrane.
 Nerve fibers normally penetrate this
structure, but small blood capillaries
(being epithelial themselves) normally
never enter epithelia.