Cardiovascular physiology
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Cardiovascular physiology is the study of the circulatory system. More specifically, it addresses the physiology of the heart ("cardio") and blood vessels ("vascular").
These subjects are sometimes addressed separately, under the names "cardiac physiology" and "circulatory physiology".[1]
Although the different aspects of cardiovascular physiology are closely interrelated, the subject is still usually divided into several subtopics.
Heart
- See Heart#Physiology for more details
- Cardiac output (= heart rate * stroke volume. Can also be calculated with Fick principle.)
- Stroke volume (= end-diastolic volume - end-systolic volume)
- Ejection fraction (= stroke volume / end-diastolic volume)
- Inotropic, chronotropic, and dromotropic states
Blood vessels
- See Blood vessel#Physiology for more details
- Compliance
- Microcirculation
- Starling equation
- Fick's law of diffusion
- Poiseuille's law
- Skeletal-muscle pump
Regulation of blood pressure
- Baroreceptor
- Baroreflex
- Renin-angiotensin system
- Juxtaglomerular apparatus
- Aortic body and carotid body
- Autoregulation
Hemodynamics
Under most circumstances, the body attempts to maintain a steady mean arterial pressure.
When there is a major and immediate decrease (such as that due to hemorrhage or standing up), the body can increase the following:
- Heart rate
- Total peripheral resistance (primarily due to vasoconstriction of arteries)
- Inotropic state
In turn, this can have a significant impact upon several other variables:
- Stroke volume
- Cardiac output
- Pressure
- Pulse pressure (systolic pressure - diastolic pressure)
- Mean arterial pressure (usually approximated with diastolic pressure + 1/3 pulse pressure)
- Central venous pressure
Regional circulation
| Name of circulation | % of cardiac output | Autoregulation | Perfusion | Comments |
| pulmonary circulation | 100% (deoxygenated) | Vasoconstriction in response to hypoxia | ||
| cerebral circulation | 15%[2] | high | under-perfused | Fixed volume means intolerance of high pressure. Minimal ability to use anaerobic respiration |
| coronary circulation | 5% | high | under-perfused | Minimal ability to use anaerobic respiration. Blood flow through the left coronary artery is at a maximum during diastole (in contrast to the rest of systemic circulation, which has a maximum blood flow during systole.) |
| splanchnic circulation | 15% | low | Flow increases during digestion. | |
| hepatic circulation | 15% | Part of portal venous system, so oncotic pressure is very low | ||
| renal circulation | 25% | high | over-perfused | Maintains glomerular filtration rate |
| skeletal muscle circulation | 17%[3] | Perfusion increases dramatically during exercise. | ||
| cutaneous circulation | 2%[4] | over-perfused | Crucial in thermoregulation. Significant ability to use anaerobic respiration |
References
External links
- Cardiovascular+physiology at the US National Library of Medicine Medical Subject Headings (MeSH)
- www.cvphsysiology.com - Comprehensive explanation of basic cardiovascular concepts.