Ch. 5 short answer Flashcards
(2 cards)
Explain the similarities and differences between mucous and serous membranes.
Both serous and mucous membranes are composed of a deep fibrous connective tissue layer and a superficial epithelium layer, both secrete fluid and function in lubrication. Serous membranes are always composed of a simple squamous epithelium layer while mucous membranes may be composed of variable epithelial tissue types. Serous membranes line internal cavities while mucous membranes line external surfaces. Serous membranes secrete serous fluid and mucous membranes secrete mucous. Besides lubrication, mucous membranes also function in protection.
Name and describe two of the four types of junctional complexes found in epithelial tissue.
The three junctional complexes found in epethelial tissue are tight junctions, desmosomes, hemidesmosomes, and gap junctions.
Tight junctions are composed of fused membrane bound proteins from adjoining cells. They form a tight fusion between cells which prevents substances from moving between the cells and prevent intermembranous proteins from freely moving about the plasma membrane.
Desmosomes are composed of protein plaques attached to tonofilaments on the interior surface of the plasma membrane, and intercellular filaments which extend through the plasma membrane to the exterior. The intercellular filaments of the desmosome of an adjoining cell interlocking like velcro. The plaque serves as an anchor and provides the strength while the linked intercellular filaments are able to attach and reattach to eachother proividing resilancy to stretching. Hemidesmosomes are similiar but only at the base of the cell and attached to the basement membrane, rather than another cell.
Tight junctions are formed by aligned gap junctions created by connexons of adjoining cells. The form a channel from one cells cytoplasm to the next and allow the exchange and passage of substances between cells based on concentration gradients.
