myogenic, and paracrine. Comprehension of the regulation of circulation of specific organs is a matter
of knowing the relative importance of each of the building blocks in a particular organ in a particular
circumstance. The coronary and cutaneous circula- tions are contrasting examples in that regulation of
coronary blood flow greatly influenced by local meta- bolic events and cutaneous blood flow is predomi-
nantly influenced by neural control related to central temperature regulation. However, in both organs
other building blocks are needed to achieve a com- plete working model of the circulatory control.
Address for reprint requests and other correspondence: H. V. Sparks, Jr., 241 Giltner Hall, Dept. of Physiology, Michigan State
Univ., East Lansing, MI 48824 E-mail: sparkspsl.msu.edu.
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