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Unformatted text preview: enous pressure and increase venous return
as more blood is returned to the heart. Increase
Increase venous volume increase venous pressure
Increase venous capacitance decrease venous pressure Sympathetic Nervous System &
Blood Pressure Mean
Mean Arterial Pressure (MAP) MAP is the average pressure that drives blood through
the systemic organs.
MAP = 1/3 (SP) + 2/3 (DP) Not simply an average of the two pressures because the
heart spends more time in diastole than it does in systole
(at rest). Blood
Blood Pressure Measurement
Sphygmomanometer – inflatable cuff and
measuring unit to restrict blood flow and
Compression of Brachial Artery Sympathetic Nervous System (SNS) – can change
arteriolar resistance and venous capacitance Greatly influence blood pressure
Norepinephrine released from these nerves binds to 1
adrenergic receptors on the smooth muscle cells and
causes vasoconstriction In the arterioles, this results in an increase in
resistance, which decreases blood flow to the venous
si d e
id On the venous side, vasoconstriction leads to a
decrease in capacitance which decreases venous
decrease in capacitance, which decreases venous
Venous constriction plays a major role in increasing
blood return to the heart Total Peripheral Resistance (TPR) TPR the overall resistance to flow
TPR – the overall resistance to flow
through the systemic cardiovascular
Can be calculated if MAP and CO ar...
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This document was uploaded on 01/13/2014.
- Winter '14