Mucous secretions that coat the passageways of the digestive and respiratory tracts result from ______ secretion.
The primary function of serous membranes in the body is:
to minimize friction between opposing surfaces.
Large muscle fibers that are multinucleated, striated, and untary are found in ___________ muscle tissue.
What are four essential functions of epithelial tissue?
provide physical protection; control permeability; provide sensations; produce specialized secretion.
What three basic components are found in connective tissues?
specialized cells, extracellular protein fibers, fluid ground substance.
Which fluid connective tissues and supporting connective tissues are found in the human body?
fluid connective tissues: blood and lymph; supporting connective tissues: bone and cartilage.
Which four kinds of membranes composed of epithelial and connective tissues cover and protect other structures and tissues in the body?
mucous, serous, cutaneous, synovial.
What two cell populations compromise neural tissue? What is the function of each?
neurons and neuroglia. The neurons transmit electrical impulses. The neuroglia comprise several kinds of supporting cells and play a role in providing nutrients to neurons.
In the body surfaces where mechanical stresses are severe, the dominant epithelium is _________ epithelium.
Why does holocrine secretion require continuous cell division?
Holocrine secretion destroys the gland cell. During holocrine secretion, the entire cell becomes packed with secretory products and then bursts, which releases the secretion but kills the cell. The gland cells must be replaced by the division of stem cells.
What is the difference between an exocrine secretion and an endocrine secretion?
Exocrine secretions are secreted onto a surface or outward through a duct. Endocrine secretions are secreted by ductless glands into surrounding tissues. The secretions are called hormones, which usually diffuse into the blood for distribution to other parts of the body.
A significant structural feature in the digestive system is the presence of tight junctions located near the exposed surfaces of cells that line the digestive tract. Why are these junctions so important?
Tight junctions block the passage of water or solutes between cells. In the digestive tract, these junctions keep enzymes, acids and wastes from damaging delicate underlying tissues.
Why are infections always a serious threat after a severe burn or a abrasion?
The extensive connections between cells formed by tight junctions, intercellular cement, and physical interlocking hold skin cells together and can deny access to chemicals or pathogens that may cover their free surfaces. If the skin is damaged and the connections are broken, infection can easily occur.