Changes: Cardiovascular system

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3DScience cardiovascular system — Diagram of the human circulatory system. Arteries and some capillaries are shown red, veins are shown blue.

The circulatory system (or cardiovascular system) is an organ system that moves nutrients, gases, and wastes to and from cells, helps fight diseases and helps stabilize body temperature and pH to maintain homeostasis. While humans, as well as other vertebrates have a closed circulatory system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have open circulatory system. The most primitive animal phyla lack circulatory systems.

Human circulatory system

File:Blutkreislauf.png

Blood circulation:
Red = oxygenated
Blue = deoxygenated

The main components of the human circulatory system are the heart, the blood, and the blood vessels. The circulatory system includes: the pulmonary circulation, a "loop" through the lungs where blood is oxygenated; and the systemic circulation, a "loop" through the rest of the body to provide oxygenated blood. An average adult contains five to six quarts of blood, which consists of plasma that contains red blood cells, white blood cells, and platelets. Two types of fluids move through the circulatory system: blood and lymph. The blood, heart, and blood vessels form the cardiovascular system. The lymph, lymph nodes, and lymph vessels form the lymphatic system. The cardiovascular system and the lymphatic system collectively make up the circulatory system.

Systemic circulation

Main article: Systemic circulation

Systemic circulation is the portion of the cardiovascular system which carries oxygenated blood away from the heart, to the body, and returns deoxygenated blood back to the heart.

Arteries always take blood away from the heart, regardless of their oxygenation, and veins always bring blood back. In general, arteries bring oxygenated blood to the tissues; veins bring deoxygenated blood back to the heart. In the case of the pulmonary vessels, however, the oxygenation is reversed: the pulmonary artery takes deoxygenated blood from the heart to the lungs, and oxygenated blood is pumped back through the pulmonary vein to the heart. As blood circulates through the body, oxygen and nutrients diffuse from the blood into cells surrounding the capillaries, and carbon dioxide diffuses into the blood from the capillary cells.

The release of oxygen from red blood cells or erythrocytes is regulated in mammals. It increases with an increase of carbon dioxide in tissues, an increase in temperature, or a decrease in pH. Such characteristics are exhibited by tissues undergoing high metabolism, as they require increased levels of oxygen.

Pulmonary circulation

Main article: Pulmonary circulation

Pulmonary circulation is the portion of the cardiovascular system which carries oxygen-depleted blood away from the heart, to the lungs, and returns oxygenated blood back to the heart.

De-oxygenated blood enters the right atrium of the heart and flows into the right ventricle where it is pumped through the pulmonary arteries to the lungs. Pulmonary veins return the now oxygen-rich blood to the heart, where it enters the left atrium before flowing into the left ventricle. From the left ventricle the oxygen-rich blood is pumped out via the aorta, and on to the rest of the body.

Coronary circulation

Main article: Coronary circulation

The Coronary circulatory system provides a blood supply to the heart.

Heart

In the heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle.

Closed circulatory system

The circulatory systems of humans is closed, meaning that the blood never leaves the system of blood vessels. In contrast, oxygen and nutrients diffuse across the blood vessel layers and enters interstitial fluid, which carries oxygen and nutrients to the target cells, and carbon dioxide and wastes in the opposite direction.

Other vertebrates

The circulatory systems of all vertebrates, as well as of annelids (for example, earthworms) and cephalopods (squid and octopus) are closed, just as in humans. Still, the systems of fish, amphibians, reptiles, and birds show various stages of the evolution of the circulatory system.

In fish, the system has only one circuit, with the blood being pumped through the capillaries of the gills and on to the capillaries of the body tissues. This is known as single circulation. The heart of fish is therefore only a single pump (consisting of two chambers). In amphibians and most reptiles, a double circulatory system is used, but the heart is not always completely separated into two pumps. Amphibians have a three-chambered heart.

Birds and mammals show complete separation of the heart into two pumps, for a total of four heart chambers; it is thought that the four-chambered heart of birds evolved independently from that of mammals.

Open circulatory system

The open circulatory system is an arrangement of internal transport present in many animals such as molluscs and arthropods, in which fluid (called hemolymph) in a cavity called the hemocoel bathes the organs directly with oxygen and nutrients and there is no distinction between blood and interstitial fluid; this combined fluid is called hemolymph or haemolymph. Muscular movements by the animal during locomotion can facilitate hemolymph movement, but diverting flow from one area to another is limited. When the heart relaxes, blood is drawn back toward the heart through open-ended pores (ostia).

Hemolymph fills all of the interior hemocoel of the body and surrounds all cells. Hemolymph is composed of water, inorganic salts (mostly Na⁺, Cl^-, K⁺, Mg²⁺, and Ca²⁺), and organic compounds (mostly carbohydrates, proteins, and lipids). The primary oxygen transporter molecule is hemocyanin.

There are free-floating cells, the hemocytes, within the hemolymph. They play a role in the arthropod immune system.

No circulatory system

Circulatory systems are absent in some animals, including flatworms (phylum Platyhelminthes). Their body cavity has no lining or enclosed fluid. Instead a muscular pharynx leads to an extensively branched digestive system that facilitates direct diffusion of nutrients to all cells. The flatworm's dorso-ventrally flattened body shape also restricts the distance of any cell from the digestive system or the exterior of the organism. Oxygen can diffuse from the surrounding water into the cells, and carbon dioxide can diffuse out. Consequently every cell is able to obtain nutrients, water and oxygen without the need of a transport system.

Measurement techniques

Health and disease

Main article: Cardiovascular disease

Main article: Congenital heart defect

History of discovery

The valves of the heart were discovered by a physician of the Hippocratean school around the 4th century BC. However their function was not properly understood then. Because blood pools in the veins after death, arteries look empty. Ancient anatomists assumed they were filled with air and that they were for transport of air.

Herophilus distinguished veins from arteries but thought that the pulse was a property of arteries themselves. Erasistratus observed that arteries that were cut during life bleed. He ascribed the fact to the phenomenon that air escaping from an artery is replaced with blood that entered by very small vessels between veins and arteries. Thus he apparently postulated capillaries but with reversed flow of blood.

The 2nd century AD, Greek physician, Galen, knew that blood vessels carried blood and identified venous (dark red) and arterial (brighter and thinner) blood, each with distinct and separate functions. Growth and energy were derived from venous blood created in the liver from chyle, while arterial blood gave vitality by containing pneuma (air) and originated in the heart. Blood flowed from both creating organs to all parts of the body where it was consumed and there was no return of blood to the heart or liver. The heart did not pump blood around, the heart's motion sucked blood in during diastole and the blood moved by the pulsation of the arteries themselves.

Galen believed that the arterial blood was created by venous blood passing from the left ventricle to the right by passing through 'pores' in the interventricular septum, air passed from the lungs via the pulmonary artery to the left side of the heart. As the arterial blood was created 'sooty' vapors were created and passed to the lungs also via the pulmonary artery to be exhaled.

In 1242, the Arabian physician, Ibn al-Nafis, became the first person to accurately describe the process of blood circulation in the human body, particularly pulmonary circulation, for which he is considered the father of circulatory physiology.^[1] Ibn al-Nafis stated in his Commentary on Anatomy in Avicenna's Canon:

"...the blood from the right chamber of the heart must arrive at the left chamber but there is no direct pathway between them. The thick septum of the heart is not perforated and does not have visible pores as some people thought or invisible pores as Galen thought. The blood from the right chamber must flow through the vena arteriosa (pulmonary artery) to the lungs, spread through its substances, be mingled there with air, pass through the arteria venosa (pulmonary vein) to reach the left chamber of the heart and there form the vital spirit..."

Contemporary drawings of this process have survived. In 1552, Michael Servetus described the same, and Realdo Colombo proved the concept, but it remained largely unknown in Europe.

Finally William Harvey, a pupil of Hieronymus Fabricius (who had earlier described the valves of the veins without recognizing their function), performed a sequence of experiments and announced in 1628 the discovery of the human circulatory system as his own and published an influential book about it. This work with its essentially correct exposition slowly convinced the medical world. Harvey was not able to identify the capillary system connecting arteries and veins; these were later described by Marcello Malpighi.

References

↑ Chairman's Reflections (2004), "Traditional Medicine Among Gulf Arabs, Part II: Blood-letting", Heart Views 5 (2), p. 74-85 [80].

External links

The Circulatory System, a comprehensive overview
The InVision Guide to a Healthy Heart An interactive website
NCP Cardiovascular Medicine A Journal Covering Clinical Cardiovascular Medicine

Human organ systems

Cardiovascular system - Digestive system - Endocrine system - Immune system - Integumentary system - Lymphatic system - Muscular system - Nervous system - Skeletal system - Reproductive system - Respiratory system - Urinary system

This page uses Creative Commons Licensed content from Wikipedia (view authors).

[1] Chairman's Reflections (2004), "Traditional Medicine Among Gulf Arabs, Part II: Blood-letting", Heart Views 5 (2), p. 74-85 [80].

[1]

v·d·e Anatomy of torso, cardiovascular system: heart
Structures	atria (interatrial septum, musculi pectinati) • ventricles (interventricular septum, trabeculae carneae, chordae tendinae, papillary muscle) • valves • cusps
Regions	base • apex • grooves (coronary/atrioventricular, interatrial, anterior interventricula, posterior interventricular) • surfaces (sternocostal, diaphragmatic) • borders (right, left)
Right heart	(vena cavae, coronary sinus) → right atrium (auricle, fossa ovalis, limbus of fossa ovalis, crista terminalis, valve of the inferior vena cava, valve of the coronary sinus) → tricuspid valve → right ventricle (conus arteriosus, moderator band/septomarginal trabecula) → pulmonary valve → (pulmonary artery and pulmonary circulation)
Left heart	(pulmonary veins) → left atrium (auricle) → mitral valve → left ventricle → aortic valve (aortic sinus) → (aorta and systemic circulation)
Layers	pericardium: fibrous pericardium • serous pericardium (pericardial cavity, epicardium/visceral layer) • pericardial sinus myocardium • endocardium • cardiac skeleton (fibrous trigone, fibrous rings)
Conduction system	Cardiac pacemaker • SA node • AV node• bundle of His • Purkinje fibers

v·d·e Cardiovascular system, physiology: cardiovascular physiology
Volumes	Preload - Afterload - End-systolic volume - End-diastolic volume - Frank-Starling law of the heart
Interactions	Cardiac output - Wiggers diagram - Pressure volume diagram
Tropism	Chronotropic - Dromotropic - Inotropic
Hemodynamics	Baroreflex - Kinin-kallikrein system - Renin-angiotensin system - Vasoconstrictors - Vasodilators - Compliance - Vascular resistance
Other	Electrical conduction system of the heart (Cardiac action potential)

v·d·e Circulatory system pathology (I, 390-459)
Hypertension	Hypertensive heart disease - Hypertensive nephropathy - Secondary hypertension (Renovascular hypertension)
Ischaemic heart disease	Angina pectoris (Prinzmetal's angina) - Myocardial infarction - Dressler's syndrome
Pulmonary circulation	Pulmonary embolism - Cor pulmonale
Pericardium	Pericarditis - Pericardial effusion - Cardiac tamponade
Endocardium/heart valves	Endocarditis - mitral valves (regurgitation, prolapse, stenosis) - aortic valves (stenosis, insufficiency) - pulmonary valves (stenosis, insufficiency) - tricuspid valves (stenosis, insufficiency)
Myocardium	Myocarditis - Cardiomyopathy (Dilated cardiomyopathy, Hypertrophic cardiomyopathy, Loeffler endocarditis, Restrictive cardiomyopathy) - Arrhythmogenic right ventricular dysplasia
Electrical conduction system of the heart	Heart block: AV block (First degree, Second degree, Third degree) - Bundle branch block (Left, Right) - Bifascicular block - Trifascicular block Pre-excitation syndrome (Wolff-Parkinson-White, Lown-Ganong-Levine) - Long QT syndrome - Adams-Stokes syndrome - Cardiac arrest Arrhythmia: Paroxysmal tachycardia (Supraventricular, AV nodal reentrant, Ventricular) - Atrial flutter - Atrial fibrillation - Ventricular fibrillation - Premature contraction (Atrial, Ventricular) - Sick sinus syndrome
Other heart conditions	Heart failure - Cardiovascular disease - Cardiomegaly - Ventricular hypertrophy (Left, Right)
Cerebrovascular diseases	Intracranial hemorrhage/cerebral hemorrhage: Extra-axial hemorrhage (Epidural hemorrhage, Subdural hemorrhage, Subarachnoid hemorrhage) - Intra-axial hematoma (Intraventricular hemorrhages, Intraparenchymal hemorrhage) - Anterior spinal artery syndrome - Binswanger's disease - Moyamoya disease
Arteries, arterioles and capillaries	Atherosclerosis (Renal artery stenosis) - Aortic dissection/Aortic aneurysm (Abdominal aortic aneurysm) - Aneurysm - Raynaud's phenomenon/Raynaud's disease - Buerger's disease - Arteritis (Aortitis) - Intermittent claudication - Arteriovenous fistula - Hereditary hemorrhagic telangiectasia - Spider angioma
Veins, lymphatic vessels and lymph nodes	Thrombosis/Phlebitis/Thrombophlebitis (Deep vein thrombosis, May-Thurner syndrome, Portal vein thrombosis, Venous thrombosis, Budd-Chiari syndrome, Renal vein thrombosis, Paget-Schroetter disease) - Varicose veins/Portacaval anastomosis (Hemorrhoid, Esophageal varices, Varicocele, Gastric varices, Caput medusae) - Superior vena cava syndrome - Lymph(Lymphadenitis, Lymphedema, Lymphangitis)
See also congenital (Q20-Q28, 745-747)

@@ Line 2: / Line 2: @@
+[[Image:3DScience cardiovascular system.jpg|thumb|right|Diagram of the human circulatory system. [[Arteries]] and some [[capillaries]] are shown red, [[vein]]s are shown blue.]]
-A '''circulatory system''' (sometimes '''cardiovascular system''') is an [[organ (anatomy)|organ system]] that moves substances to and from [[cell (biology)|cells]]; it can also help stabilize body temperature and [[pH]] (part of [[homeostasis]]). There are three types of circulatory systems (from simplest to most complex): '''no circulatory system''', '''open circulatory system''', and '''closed circulatory system'''.
+The '''circulatory system''' (or ''' cardiovascular system''') is an [[organ (anatomy)|organ system]] that moves nutrients, gases, and wastes to and from [[cell (biology)|cells]], helps fight diseases and helps stabilize body temperature and [[pH]] to  maintain [[homeostasis]]. While humans, as well as other [[vertebrates]] have a '''closed circulatory system''' (meaning that the blood never leaves the network of arteries, veins and capillaries), some [[invertebrate]] groups have '''open circulatory system'''. The most primitive animal [[phylum|phyla]] lack circulatory systems.
-==No circulatory system==
+==Human circulatory system==
+[[Image:Blutkreislauf.png|thumb|upright|right|Blood circulation:<br>Red = oxygenated<br>Blue = deoxygenated]]
-An example of an animal with no circulatory system is the flatworm (class Turbellaria). Their [[body cavity]] has no lining or fluid. They have a mouth leading into a digestive system. The digestive system is very branched, and because the worm is so flat, digested materials can be diffused to all the cells of the flat worm. Oxygen can diffuse from water into the cells of the flatworm. Thus every cell is able to obtain nutrients, water and oxygen without the need of a transport system
+The main components of the human circulatory system are the [[heart]], the [[blood]], and the [[blood vessel]]s.     The circulatory system includes: the [[pulmonary circulation]], a "loop" through the [[lung]]s where blood is oxygenated; and the [[systemic circulation]], a "loop" through the rest of the body to provide [[oxygenate]]d blood. An average adult contains five to six quarts of blood, which consists of plasma that contains [[red blood cells]], [[white blood cells]], and [[platelets]].
+Two types of fluids move through the circulatory system: blood and lymph. The blood, heart, and blood vessels form the [[cardiovascular system]]. The lymph, lymph nodes, and lymph vessels form the [[lymphatic system]]. The cardiovascular system and the lymphatic system collectively make up the circulatory system.
+===Systemic circulation===
-==Open circulatory system==
+{{Main|Systemic circulation}}
+Systemic circulation is the portion of the cardiovascular system which carries [[oxygen]]ated [[blood]] away from the [[heart]], to the [[body]], and returns deoxygenated blood back to the heart.
+[[Arteries]] always take blood away from the heart, regardless of their oxygenation, and [[vein]]s always bring blood back. In general, arteries bring oxygenated blood to the tissues; veins bring deoxygenated blood back to the heart. In the case of the [[pulmonary vessels]], however, the oxygenation is reversed: the [[pulmonary artery]] takes deoxygenated blood from the heart to the lungs, and oxygenated blood is pumped back through the [[pulmonary vein]] to the heart. As blood circulates through the body, oxygen and nutrients diffuse from the blood into cells surrounding the [[capillaries]], and carbon dioxide diffuses into the blood from the capillary cells.
-An '''open circulatory system''' is an arrangement of internal transport present in some [[invertebrate]]s like [[mollusk]]s and [[arthropod]]s in which circulatory fluid in a cavity called the '''hemocoel''' bathes the organs directly and there is no distinction between [[blood]] and [[interstitial fluid]]; this combined fluid is called '''''hemolymph''''' (also spelled '''''haemolymph'''''). Muscular movements by the animal during locomotion can facilitate hemolymph movement, but diverting flow from one area to another is limited. When the [[heart]] relaxes, blood is drawn back toward the heart through open-ended pores.
+The release of oxygen from red blood cells or [[erythrocyte]]s is regulated in mammals. It increases with an increase of [[carbon dioxide]] in [[tissues]], an increase in temperature, or a decrease in pH. Such characteristics are exhibited by tissues undergoing high metabolism, as they require increased levels of [[oxygen]].
-'Hemolymph fills all of the interior (hemocoel) of the body and surrounds all [[cell (biology)|cell]]s.
+===Pulmonary circulation===
-Hemolymph is composed of [[water]], [[inorganic chemistry|inorganic]] [[salt]]s (mostly [[Sodium|Na<sup>+</sup>]], [[Chlorine|Cl<sup>-</sup>]], [[Potassium|K<sup>+</sup>]], [[Magnesium|Mg<sup>2+</sup>]], and [[Calcium|Ca<sup>2+</sup>]]), and [[organic chemistry|organic compounds]] (mostly [[carbohydrate]]s, [[protein]]s, and [[lipid]]s).  The primary oxygen transporter molecule is [[hemocyanin]].
+{{Main|Pulmonary circulation}}
+Pulmonary circulation is the portion of the cardiovascular system which carries [[oxygen]]-depleted [[blood]] away from the heart, to the [[lungs]], and returns oxygenated blood back to the heart.
+De-oxygenated blood enters the right atrium of the heart and flows into the right ventricle where it is pumped through the pulmonary arteries to the lungs. Pulmonary veins return the now oxygen-rich blood to the heart, where it enters the left atrium before flowing into the left ventricle. From the left ventricle the oxygen-rich blood is pumped out via the aorta, and on to the rest of the body.
-There are free-floating cells, the [[hemocyte]]s, within the hemolymph. They play a role in the arthropod [[immune system]].
+===Coronary circulation===
-==Closed circulatory system==
+{{Main|Coronary circulation}}
-The main organs of the circulatory system is the heart, the blood, and the blood vessels.
+The Coronary circulatory system provides a blood supply to the heart.
+===Heart===
-The circulatory systems of all [[vertebrate]]s, as well as of annelids (for example, [[earthworm]]s) and cephalopods (squid and octopus) are ''closed'', meaning that the blood never leaves the system of blood vessels consisting of arteries, capillaries and veins.
+In the [[heart]] there is one [[atrium (heart)|atrium]] and one [[Ventricle (heart)|ventricle]] for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: [[left atrium]], [[left ventricle]], [[right atrium]] and [[right ventricle]].
+===Closed circulatory system===
-The systems of [[fish]], [[amphibian]]s, [[reptile]]s, [[bird]]s and [[mammal]]s show various stages of [[evolution]].
+The circulatory systems of humans is closed, meaning that the blood never leaves the system of [[blood vessels]]. In contrast, oxygen and nutrients diffuse across the blood vessel layers and enters [[interstitial fluid]], which carries oxygen and nutrients to the target cells, and carbon dioxide and wastes in the opposite direction.
+==Other vertebrates==
-In fish, the system has only one circuit, with the blood being pumped through the capillaries of the gills and on to the [[Capillary|capillaries]] of the body tissues. This is known as ''single'' circulation. The heart of fish is therefore only a single pump (consisting of two chambers).
+The circulatory systems of all [[vertebrate]]s, as well as of [[annelid]]s (for example, [[earthworm]]s) and [[cephalopod]]s ([[squid]] and [[octopus]]) are ''closed'', just as in humans. Still, the systems of [[fish]], [[amphibian]]s, [[reptile]]s, and [[bird]]s show various stages of the [[evolution]] of the circulatory system.
-In amphibians and reptiles, a double circulatory system is used, but the heart is not always completely separated into two pumps. Amphibians have a three-chambered heart.
+In fish, the system has only one circuit, with the blood being pumped through the capillaries of the [[gill]]s and on to the capillaries of the body tissues. This is known as ''single'' circulation. The heart of fish is therefore only a single pump (consisting of two chambers). In amphibians and most reptiles, a [[double circulatory system]] is used, but the heart is not always completely separated into two pumps. Amphibians have a three-chambered heart.
-Birds and mammals show complete separation of the heart into two pumps, for a total of four heart chambers; it is thought that the four-chambered heart of birds evolved independently of that of mammals.
+Birds and mammals show complete separation of the heart into two pumps, for a total of four heart chambers; it is thought that the four-chambered heart of birds evolved independently from that of mammals.
-===Mammalian circulation===
+== Open circulatory system ==
-Deoxygenated blood (containing little or no oxygen) collects in two major veins: the superior vena cava and the inferior vena cava. The superior and inferior vena cava empty into the right atrium. The right atrium is the larger of the two atriums because it needs to be able to hold the larger amount of blood coming from the body (as opposed to the amount coming from the lungs). The blood is then pumped through the tricuspid atrioventicular valve into the right ventricle. From the right ventricle, blood is pumped through the pulmonary semi-lunar valve into the pulmonary trunk.  The deoxygenated blood leaves the heart by the pulmonary arteries and travels through the lungs (where it is oxygenated) and into the pulmonary vein. The oxygenated blood then enters the left atrium. The blood then travels through the bicuspid valve, or mitral valve, into the left ventricle. The left ventricle is thicker and more muscular than the right ventricle because it pumps blood throughout the body, systemic circulation. From the left ventricle, blood is pumped through the semi-lunar valve into the [[aorta]]. Once the blood goes through systemic circulation, deoxygenated blood will again collect inside the vena cava and the process will continue.
+The '''open circulatory system''' is an arrangement of internal transport present in many animals such as [[mollusc]]s and [[arthropod]]s, in which fluid (called [[hemolymph]]) in a cavity called the [[hemocoel]] bathes the organs directly with oxygen and nutrients and there is no distinction between [[blood]] and [[interstitial fluid]]; this combined fluid is called hemolymph or haemolymph. Muscular movements by the animal during [[Animal locomotion|locomotion]] can facilitate hemolymph movement, but diverting flow from one area to another is limited. When the [[heart]] relaxes, blood is drawn back toward the heart through open-ended pores (ostia).
+Hemolymph fills all of the interior hemocoel of the body and surrounds all [[cell (biology)|cell]]s. Hemolymph is composed of [[water]], [[inorganic chemistry|inorganic]] [[salt]]s (mostly [[Sodium|Na<sup>+</sup>]], [[Chlorine|Cl<sup>-</sup>]], [[Potassium|K<sup>+</sup>]], [[Magnesium|Mg<sup>2+</sup>]], and [[Calcium|Ca<sup>2+</sup>]]), and [[organic chemistry|organic compounds]] (mostly [[carbohydrate]]s, [[protein]]s, and [[lipid]]s). The primary oxygen transporter molecule is [[hemocyanin]].
-==Measurement techniques==
-*[[Electrocardiogram]]
-*[[Sphygmomanometer]]
-*[[Pulse meter]]
+There are free-floating cells, the [[hemocyte]]s, within the hemolymph. They play a role in the arthropod [[immune system]].
+== No circulatory system ==
+Circulatory systems are absent in some animals, including [[flatworms]] (phylum [[Platyhelminthes]]). Their [[body cavity]] has no lining or enclosed fluid. Instead a muscular [[pharynx]] leads to an extensively branched [[digestive system]] that facilitates direct [[diffusion]] of nutrients to all cells. The flatworm's dorso-ventrally flattened body shape also restricts the distance of any cell from the digestive system or the exterior of the organism. Oxygen can diffuse from the surrounding [[water]] into the cells, and carbon dioxide can diffuse out. Consequently every cell is able to obtain nutrients, water and oxygen without the need of a transport system.
+== Measurement techniques ==
+* [[Electrocardiogram]]
+* [[Sphygmomanometer]]
+* [[Pulse meter]]
+* [[Stethoscope]]
+* [[Pulse]]
-==Health and disease==
+== Health and disease ==
 {{main|Cardiovascular disease}}
+{{main|Congenital heart defect}}
-==History of discovery==
+== History of discovery ==
-The valves of the heart were discovered by a physician of the Hippocratean school around the [[4th century BC]]. However their function was not properly understood then.  Because blood pools in the veins after death, arteries look empty.  Ancient anatomists assumed they were filled with air and that they were for transport of air.
+The valves of the heart were discovered by a physician of the Hippocratean school around the [[4th century BC]]. However their function was not properly understood then. Because blood pools in the veins after death, arteries look empty. Ancient anatomists assumed they were filled with air and that they were for transport of air.
 [[Herophilus]] distinguished veins from arteries but thought that the pulse was a property of arteries themselves. Erasistratus observed that arteries that were cut during life bleed. He ascribed the fact to the phenomenon that air escaping from an artery is replaced with blood that entered by very small vessels between veins and arteries. Thus he apparently postulated capillaries but with reversed flow of blood.
-The [[2nd century]] AD greek physician, [[Galen]] knew that blood vessels carry blood and identified venous (dark red) and arterial (brighter and thinner) blood, each with distinct and separate functions. Growth and energy were derived from venous blood created in the liver from chyle, while arterial blood gave vitality by containing pneuma (air) and originated in the heart. Blood flowed from both creating organs to all parts of the body where it was consumed and there was no return of blood to the heart or liver. The heart did not pump blood around, the heart's motion sucked blood in during diastole and the blood moved by the pulsation of the arteries themselves.
+The [[2nd century]] AD, Greek physician, [[Galen]], knew that blood vessels carried blood and identified venous (dark red) and arterial (brighter and thinner) blood, each with distinct and separate functions. Growth and energy were derived from venous blood created in the liver from chyle, while arterial blood gave vitality by containing pneuma (air) and originated in the heart. Blood flowed from both creating organs to all parts of the body where it was consumed and there was no return of blood to the heart or liver. The heart did not pump blood around, the heart's motion sucked blood in during diastole and the blood moved by the pulsation of the arteries themselves.
-Galen believed that the arterial blood was created by venous blood passing from the left ventricle to the right by passing through '[[pore]]s' in the interventricular septum, air passed from the lungs via the pulmonary artery to the left side of the heart. As the arterial blood was created 'sooty' vapors were created and passed to the lungs also via the pulmonary artery to be exhaled.
+Galen believed that the arterial blood was created by venous blood passing from the left ventricle to the right by passing through 'pores' in the interventricular septum, air passed from the lungs via the pulmonary artery to the left side of the heart. As the arterial blood was created 'sooty' vapors were created and passed to the lungs also via the pulmonary artery to be exhaled.
-[[Ibn Nafis]] in [[1242]] was the first person to accurately describe the process of blood circulation in the human body. Contemporary drawings of this process have survived. In [[1552]] Servetus described the same and [[Realdo Colombo]] proved the concept. All these results were not widely accepted however.
+In [[1242]], the [[Islamic medicine|Arabian physician]], [[Ibn al-Nafis]], became the first person to accurately describe the process of blood circulation in the human body, particularly [[pulmonary circulation]], for which he is considered the father of [[Cardiovascular physiology|circulatory physiology]].<ref>Chairman's Reflections (2004), "Traditional Medicine Among Gulf Arabs, Part II: Blood-letting", ''Heart Views'' '''5''' (2), p. 74-85 [80].</ref> Ibn al-Nafis stated in his ''Commentary on Anatomy in Avicenna's Canon'':
+<blockquote>"...the blood from the right chamber of the heart must arrive at the left chamber but there is no direct pathway between them. The thick septum of the heart is not perforated and does not have visible pores as some people thought or invisible pores as Galen thought. The blood from the right chamber must flow through the vena arteriosa ([[pulmonary artery]]) to the lungs, spread through its substances, be mingled there with air, pass through the arteria venosa ([[pulmonary vein]]) to reach the left chamber of the heart and there form the vital spirit..."</blockquote>
+Contemporary drawings of this process have survived. In [[1552]], [[Michael Servetus]] described the same, and [[Realdo Colombo]] proved the concept, but it remained largely unknown in Europe.
 Finally [[William Harvey]], a pupil of [[Hieronymus Fabricius]] (who had earlier described the valves of the veins without recognizing their function), performed a sequence of experiments and announced in [[1628]] the discovery of the human circulatory system as his own and published [[Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus|an influential book]] about it. This work with its essentially correct exposition slowly convinced the medical world. Harvey was not able to identify the capillary system connecting arteries and veins; these were later described by [[Marcello Malpighi]].
-==See also==
+== See also ==
+<div style="-moz-column-count:3; column-count:3;">
-*[[Cardiology]]
-*[[Lymphatic system]]
+* [[Blood brain barrier]]
-*[[Blood vessels]]
+* [[Blood vessels]]
+* [[Cardiac muscle]]
+* [[Cardiology]]
+* [[Cadiovascular disorders]]
+* [[Cardiovascular reactivity]]
+* [[Heart]]
+* [[Lymphatic system]]
+* [[Major systems of the human body]]
+</div>
+== References ==
+{{reflist}}
 == External links ==
-* [http://cardiovascular.on-topic.net/ Cardiovascular Topics]
-* [http://www.ncvc.go.jp/english/res/Car_Dyn_A.html Studies on Hemodynamics and Coronary Circulation]
 * [http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html The Circulatory System], a comprehensive overview
 * [http://www.invisionguide.com/heart The InVision Guide to a Healthy Heart] An interactive website
+* [http://www.nature.com/ncpcardio/index.html NCP Cardiovascular Medicine] A Journal Covering Clinical Cardiovascular Medicine
+{{organ_systems}}
-== References ==
-* Iskandar, Albert Z. [http://www.islamset.com/isc/nafis/iskandar.html "Comprehensive Book on the Art of Medicine by Ibn al-Nafis"]. Retrieved [[May 2]] [[2005]]. <!-- Used to verify date of Ibn Nafis description of circulatory system as 1242 -->
 {{cardiovascular_system}}
-{{organ_systems}}
+{{Heart}}
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+[[Category:Anatomical systems]]
+[[Category:Cardiovascular system| ]]
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