History of Cardiovascular Physiology, Dr. D. Penney
Everyday Evidence of your Cardiovascular System:
- Pulse at neck, radial artery, etc. - maximum pressure in vessel due to ejection of blood by heart is felt as thump, thus thump rate = HR.
- Heart "skipping beat" - ectopic pacemaker, extra-systole, prolonged refractoriness (momentary 3rd degree heart block), failure of impulse conduction from SA node to ventricles, pause gives extra strong beat, over-filling of ventricle, Starling mechanism.
- Heart speeding when anxious/fearful - increased sympathetic drive, adrenaline; hypotension?, relief of parasympathetic inhibition.
- Heart/pulse speeding during exercise - increased blood flow required.
- Graying/blacking-out upon standing up (orthostatic hypotension) - due to lower body venous pooling, decreased B.P., decreased brain blood flow.
- "Pumping up" veins when flexing muscles - Valsalva maneuver, increased pressure in muscle forces vein toward surface, squeezing out venous blood, cannot return to heart.
- Blushing - dilatation of cutaneous precapillary vessels.
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