Cardiovascular physiology
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Cardiovascular physiology is the study of the
cardiovascular system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
, specifically addressing the
physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
of the
heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
("cardio") and
blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...
s ("vascular"). These subjects are sometimes addressed separately, under the names cardiac physiology and circulatory physiology. Although the different aspects of cardiovascular physiology are closely interrelated, the subject is still usually divided into several subtopics.


Heart

*
Cardiac output In cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols Q, \dot Q, or \dot Q_ , edited by Catherine E. Williamson, Phillip Bennett is the volumetric flow rate of the heart's pumping output: t ...
(=
heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
*
stroke volume In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the left ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood i ...
. Can also be calculated with
Fick principle The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known: * Amount of marker substance taken up by the organ per unit time * Concentration of marker substance in arteria ...
,palpeting method.) **
Stroke volume In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the left ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood i ...
(=
end-diastolic volume In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right or left ventricle at end of filling in diastole which is ammount of blood present in ventricle at the end of diastole systole. Because greater EDVs cause g ...
end-systolic volume End-systolic volume (ESV) is the volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole. ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle. The main facto ...
) **
Ejection fraction An ejection fraction (EF) is the volumetric fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or heartbeat). It can refer to the cardiac atrium, ventricle, gall bladder, ...
(= stroke volume / end-diastolic volume) **
Cardiac output In cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols Q, \dot Q, or \dot Q_ , edited by Catherine E. Williamson, Phillip Bennett is the volumetric flow rate of the heart's pumping output: t ...
is mathematically ` to
systole Systole ( ) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. The term originates, via New Latin, from Ancient Greek (''sustolē''), from (''sustéllein'' 'to contract'; from ''sun ...
**
Inotropic An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction. The term ''inotro ...
,
chronotropic Chronotropic effects (from ''chrono-'', meaning time, and ''tropos'', "a turn") are those that change the heart rate. Chronotropic drugs may change the heart rate and rhythm by affecting the electrical conduction system of the heart and the ner ...
, and dromotropic states **
Cardiac input The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
(=
heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
* suction volume Can be calculated by inverting terms in
Fick principle The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known: * Amount of marker substance taken up by the organ per unit time * Concentration of marker substance in arteria ...
) ** Suction volume (=
end-systolic volume End-systolic volume (ESV) is the volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole. ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle. The main facto ...
+
end-diastolic volume In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right or left ventricle at end of filling in diastole which is ammount of blood present in ventricle at the end of diastole systole. Because greater EDVs cause g ...
) **
Injection fraction An ejection fraction (EF) is the volumetric fraction (mathematics), fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or cardiac cycle, heartbeat). It can refer to the card ...
(=suction volume / end-systolic volume) **
Cardiac input The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
is mathematically ` to
diastole Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are re-filling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventric ...
*
Electrical conduction system of the heart The cardiac conduction system (CCS) (also called the electrical conduction system of the heart) transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through the ...
** Electrocardiogram **
Cardiac marker Cardiac markers are biomarkers measured to evaluate heart function. They can be useful in the early prediction or diagnosis of disease. Although they are often discussed in the context of myocardial infarction, other conditions can lead to an eleva ...
**
Cardiac action potential The cardiac action potential is a brief change in voltage ( membrane potential) across the cell membrane of heart cells. This is caused by the movement of charged atoms (called ions) between the inside and outside of the cell, through proteins c ...
* Frank–Starling law of the heart *
Wiggers diagram A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases ...
*
Pressure volume diagram Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...


Regulation of blood pressure

* Baroreceptor *
Baroreflex The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the ...
*
Renin–angiotensin system The renin–angiotensin system (RAS), or renin–angiotensin–aldosterone system (RAAS), is a hormone system that regulates blood pressure, fluid and electrolyte balance, and systemic vascular resistance. When renal blood flow is reduced, juxt ...
**
Renin Renin (etymology and pronunciation), also known as an angiotensinogenase, is an aspartic protease protein and enzyme secreted by the kidneys that participates in the body's renin–angiotensin–aldosterone system (RAAS)—also known as the r ...
**
Angiotensin Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adrena ...
*
Juxtaglomerular apparatus The juxtaglomerular apparatus (also known as the juxtaglomerular complex) is a structure in the kidney that regulates the function of each nephron, the functional units of the kidney. The juxtaglomerular apparatus is named because it is next to ...
*
Aortic body The aortic bodies are one of several small clusters of peripheral chemoreceptors located along the aortic arch. They are important in measuring partial pressures of oxygen and carbon dioxide in the blood, and blood pH. Structure The aortic bodies ...
and
carotid body The carotid body is a small cluster of chemoreceptor cells, and supporting sustentacular cells. The carotid body is located in the adventitia, in the bifurcation (fork) of the common carotid artery, which runs along both sides of the neck. The ca ...
*
Autoregulation Autoregulation is a process within many biological systems, resulting from an internal adaptive mechanism that works to adjust (or mitigate) that system's response to stimuli. While most systems of the body show some degree of autoregulation, it ...
**
Cerebral Autoregulation Cerebral autoregulation is a process in mammals, which aims to maintain adequate and stable cerebral blood flow. While most systems of the body show some degree of autoregulation, the brain is very sensitive to over- and underperfusion. Cerebral au ...


Hemodynamics

Under most circumstances, the body attempts to maintain a steady
mean arterial pressure In medicine, the mean arterial pressure (MAP) is an average blood pressure in an individual during a single cardiac cycle. MAP is altered by cardiac output and systemic vascular resistance. Testing Mean arterial pressure can be measured dire ...
. When there is a major and immediate decrease (such as that due to
hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...
or standing up), the body can increase the following: *
Heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
*
Total peripheral resistance Vascular resistance is the resistance that must be overcome to push blood through the circulatory system and create flow. The resistance offered by the systemic circulation is known as the systemic vascular resistance (SVR) or may sometimes be ca ...
(primarily due to
vasoconstriction Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
of
arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...
) * Inotropic state In turn, this can have a significant impact upon several other variables: *
Stroke volume In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the left ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood i ...
*
Cardiac output In cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols Q, \dot Q, or \dot Q_ , edited by Catherine E. Williamson, Phillip Bennett is the volumetric flow rate of the heart's pumping output: t ...
* Pressure **
Pulse pressure Pulse pressure is the difference between systolic and diastolic blood pressure. It is measured in millimeters of mercury (mmHg). It represents the force that the heart generates each time it contracts. Resting blood pressure is normally approx ...
( systolic pressure -
diastolic pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...
) **
Mean arterial pressure In medicine, the mean arterial pressure (MAP) is an average blood pressure in an individual during a single cardiac cycle. MAP is altered by cardiac output and systemic vascular resistance. Testing Mean arterial pressure can be measured dire ...
(usually approximated with diastolic pressure + 1/3 pulse pressure) **
Central venous pressure Central venous pressure (CVP) is the blood pressure in the venae cavae, near the right atrium of the heart. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood back into the arterial system. CVP is ...


Regional circulation


See also

*
Cardiovascular System Dynamics Society The Cardiovascular System Dynamics Society (CSDS), founded on 5 October 1976 in Philadelphia, Pennsylvania, by organ system physiologist and biomedical engineers, was a historic first in its mathematical and quantitative approach to cardiovascular m ...


References


External links

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''Cardiovascular Physiology Concepts''
- Comprehensive explanation of basic cardiovascular concepts, based on a textbook of the same name.
The Gross Physiology of the Cardiovascular System
- Mechanical overview of cardiovascular function. Free eBook and video resources.
Clinical Sciences - Cardiovascular
An iPhone app covering detailed cardiovascular physiology and anatomy

{{Cardiovascular physiology Cardiology Circulatory system Heart Cardiac anatomy