Doctor Dolittle Visits a Sitting Case

James R. Munis

in Just Enough Physiology

Published on behalf of © Mayo Foundation for Medical Education and Research

Published in print December 2011 | ISBN: 9780199797790
Published online June 2012 | e-ISBN: 9780199929665 | DOI:

Series: Mayo Clinic Scientific Press

Doctor Dolittle Visits a Sitting Case

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Any acceptable model must explain why the cerebral circulation must be robust enough to contend with different head positions yet continues to work in weightless environments (ie, during space flight) and it must explain the clinical phenomenon of air embolism, which is what happens when air gets sucked into perforated veins or sinuses when the surgical site is above the heart. 2 models of the cerebral circulation: the first is a common-sense model that most of us would draw without having thought about it much; the second is a model that makes a lot more physical sense and answers the questions above in a way that the first model cannot. The main difference between these models is that the correct one takes into account the principle of the siphon, whereas the incorrect one does not. A siphon is any arrangement of fluid-filled tubing that excludes air and is open on both ends to allow flow. It happens that the cerebral circulation functions like a siphon.

Chapter.  3707 words.  Illustrated.

Subjects: Professional Development in Medicine

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