The Info List - Cardiovascular

The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and pH, and maintain homeostasis. The circulatory system includes the lymphatic system, which circulates lymph.[1] The passage of lymph for example takes much longer than that of blood.[2] Blood
is a fluid consisting of plasma, red blood cells, white blood cells, and platelets that is circulated by the heart through the vertebrate vascular system, carrying oxygen and nutrients to and waste materials away from all body tissues. Lymph
is essentially recycled excess blood plasma after it has been filtered from the interstitial fluid (between cells) and returned to the lymphatic system. The cardiovascular (from Latin words meaning "heart" and "vessel") system comprises the blood, heart, and blood vessels.[3] The lymph, lymph nodes, and lymph vessels form the lymphatic system, which returns filtered blood plasma from the interstitial fluid (between cells) as lymph. The circulatory system of the blood is seen as having two components, a systemic circulation and a pulmonary circulation.[4] While humans, as well as other vertebrates, have a closed cardiovascular system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open cardiovascular system. The lymphatic system, on the other hand, is an open system providing an accessory route for excess interstitial fluid to be returned to the blood.[5] The more primitive, diploblastic animal phyla lack circulatory systems. Many diseases affect the circulatory system. This includes cardiovascular disease, affecting the cardiovascular system, and lymphatic disease affecting the lymphatic system. Cardiologists are medical professionals which specialise in the heart, and cardiothoracic surgeons specialise in operating on the heart and its surrounding areas. Vascular surgeons focus on other parts of the circulatory system.


1 Structure

1.1 Cardiovascular system

1.1.1 Arteries 1.1.2 Capillaries 1.1.3 Veins 1.1.4 Coronary vessels 1.1.5 Portal
veins 1.1.6 Heart 1.1.7 Lungs 1.1.8 Systemic circulation 1.1.9 Brain 1.1.10 Kidneys

1.2 Lymphatic system

2 Development

2.1 Heart 2.2 Arteries 2.3 Veins

3 Function

3.1 Cardiovascular system 3.2 Lymphatic system

4 Clinical significance

4.1 Cardiovascular disease 4.2 Investigations 4.3 Surgery

5 Society and culture 6 Other animals

6.1 Open circulatory system 6.2 Closed circulatory system 6.3 No circulatory system

7 History 8 See also 9 References 10 External links

Structure Cardiovascular system

Depiction of the heart, major veins and arteries constructed from body scans.

Cross section of a human artery

Relative percentages of cardiac output delivered to major organ systems

The essential components of the human cardiovascular system are the heart, blood and blood vessels.[6] It 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. The systemic circulation can also be seen to function in two parts–a macrocirculation and a microcirculation. An average adult contains five to six quarts (roughly 4.7 to 5.7 liters) of blood, accounting for approximately 7% of their total body weight.[7] Blood
consists of plasma, red blood cells, white blood cells, and platelets. Also, the digestive system works with the circulatory system to provide the nutrients the system needs to keep the heart pumping.[8] The cardiovascular systems of humans are closed, meaning that the blood never leaves the network of blood vessels. In contrast, oxygen and nutrients diffuse across the blood vessel layers and enter interstitial fluid, which carries oxygen and nutrients to the target cells, and carbon dioxide and wastes in the opposite direction. The other component of the circulatory system, the lymphatic system, is open. Arteries See also: Arterial tree Oxygenated blood enters the systemic circulation when leaving the left ventricle, through the aortic semilunar valve. The first part of the systemic circulation is the aorta, a massive and thick-walled artery. The aorta arches and gives branches supplying the upper part of the body after passing through the aortic opening of the diaphragm at the level of thoracic ten vertebra, it enters the abdomen. Later it descends down and supplies branches to abdomen, pelvis, perineum and the lower limbs. The walls of aorta are elastic. This elasticity helps to maintain the blood pressure throughout the body. When the aorta receives almost five litres of blood from the heart, it recoils and is responsible for pulsating blood pressure. Moreover, as aorta branches into smaller arteries, their elasticity goes on decreasing and their compliance goes on increasing. Capillaries Arteries
branch into small passages called arterioles and then into the capillaries.[9] The capillaries merge to bring blood into the venous system.[10] Veins After their passage through body tissues, capillaries merge once again into venules, which continue to merge into veins. The venous system finally coalesces into two major veins: the superior vena cava (roughly speaking draining the areas above the heart) and the inferior vena cava (roughly speaking from areas below the heart). These two great vessels empty into the right atrium of the heart. Coronary vessels Main article: Coronary circulation The heart itself is supplied with oxygen and nutrients through a small "loop" of the systemic circulation and derives very little from the blood contained within the four chambers. Portal
veins Main article: Portal
vein The general rule is that arteries from the heart branch out into capillaries, which collect into veins leading back to the heart. Portal
veins are a slight exception to this. In humans the only significant example is the hepatic portal vein which combines from capillaries around the gastrointestinal tract where the blood absorbs the various products of digestion; rather than leading directly back to the heart, the hepatic portal vein branches into a second capillary system in the liver. Heart Main article: Heart

View from the front

The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human 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. The right atrium is the upper chamber of the right side of the heart. The blood that is returned to the right atrium is deoxygenated (poor in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery to the lungs for re-oxygenation and removal of carbon dioxide. The left atrium receives newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into the strong left ventricle to be pumped through the aorta to the different organs of the body. The coronary circulation system provides a blood supply to the heart muscle itself. The coronary circulation begins near the origin of the aorta by two coronary arteries: the right coronary artery and the left coronary artery. After nourishing the heart muscle, blood returns through the coronary veins into the coronary sinus and from this one into the right atrium. Back flow of blood through its opening during atrial systole is prevented by the Thebesian valve. The smallest cardiac veins drain directly into the heart chambers.[8]


The pulmonary circulation as it passes from the heart. Showing both the pulmonary and bronchial arteries.

Main article: Pulmonary circulation The circulatory system of the lungs is the portion of the cardiovascular system in which oxygen-depleted blood is pumped away from the heart, via the pulmonary artery, to the lungs and returned, oxygenated, to the heart via the pulmonary vein. Oxygen
deprived blood from the superior and inferior vena cava enters the right atrium of the heart and flows through the tricuspid valve (right atrioventricular valve) into the right ventricle, from which it is then pumped through the pulmonary semilunar valve into the pulmonary artery to the lungs. Gas exchange
Gas exchange
occurs in the lungs, whereby CO2 is released from the blood, and oxygen is absorbed. The pulmonary vein returns the now oxygen-rich blood to the left atrium.[8] A separate system known as the bronchial circulation supplies blood to the tissue of the larger airways of the lung. Systemic circulation

The systemic circulation and capillary networks shown and also as separate from the pulmonary circulation

Systemic circulation
Systemic circulation
is the portion of the cardiovascular system which transports oxygenated blood away from the heart through the aorta from the left ventricle where the blood has been previously deposited from pulmonary circulation, to the rest of the body, and returns oxygen-depleted blood back to the heart.[8] Brain Main article: Cerebral circulation The brain has a dual blood supply that comes from arteries at its front and back. These are called the "anterior" and "posterior" circulation respectively. The anterior circulation arises from the internal carotid arteries and supplies the front of the brain. The posterior circulation arises from the vertebral arteries, and supplies the back of the brain and brainstem. The circulation from the front and the back join together (anastomise) at the Circle of Willis. Kidneys The renal circulation receives around 20% of the cardiac output. It branches from the abdominal aorta and returns blood to the ascending vena cava. It is the blood supply to the kidneys, and contains many specialized blood vessels. Lymphatic system Main article: Lymphatic system The lymphatic system is part of the circulatory system. It is a network of lymphatic vessels and lymph capillaries, lymph nodes and organs, and lymphatic tissues and circulating lymph. One of its major functions is to carry the lymph, draining and returning interstitial fluid back towards the heart for return to the cardiovascular system, by emptying into the lymphatic ducts. Its other main function is in the adaptive immune system.[11] Development Main article: Fetal circulation The development of the circulatory system starts with vasculogenesis in the embryo. The human arterial and venous systems develop from different areas in the embryo. The arterial system develops mainly from the aortic arches, six pairs of arches which develop on the upper part of the embryo. The venous system arises from three bilateral veins during weeks 4 – 8 of embryogenesis. Fetal circulation begins within the 8th week of development. Fetal circulation
Fetal circulation
does not include the lungs, which are bypassed via the truncus arteriosus. Before birth the fetus obtains oxygen (and nutrients) from the mother through the placenta and the umbilical cord.[12] Heart Main article: Heart
development Arteries Main article: Aortic arches The human arterial system originates from the aortic arches and from the dorsal aortae starting from week 4 of embryonic life. The first and second aortic arches regress and forms only the maxillary arteries and stapedial arteries respectively. The arterial system itself arises from aortic arches 3, 4 and 6 (aortic arch 5 completely regresses). The dorsal aortae, present on the dorsal side of the embryo, are initially present on both sides of the embryo. They later fuse to form the basis for the aorta itself. Approximately thirty smaller arteries branch from this at the back and sides. These branches form the intercostal arteries, arteries of the arms and legs, lumbar arteries and the lateral sacral arteries. Branches to the sides of the aorta will form the definitive renal, suprarenal and gonadal arteries. Finally, branches at the front of the aorta consist of the vitelline arteries and umbilical arteries. The vitelline arteries form the celiac, superior and inferior mesenteric arteries of the gastrointestinal tract. After birth, the umbilical arteries will form the internal iliac arteries. Veins The human venous system develops mainly from the vitelline veins, the umbilical veins and the cardinal veins, all of which empty into the sinus venosus. Function Cardiovascular system

Animation of a typical human red blood cell cycle in the circulatory system. This animation occurs at a faster rate (~20 seconds of the average 60-second cycle) and shows the red blood cell deforming as it enters capillaries, as well as the bars changing color as the cell alternates in states of oxygenation along the circulatory system.

Main article: Blood
§  Oxygen
transport About 98.5% of the oxygen in a sample of arterial blood in a healthy human, breathing air at sea-level pressure, is chemically combined with hemoglobin molecules. About 1.5% is physically dissolved in the other blood liquids and not connected to hemoglobin. The hemoglobin molecule is the primary transporter of oxygen in mammals and many other species. Lymphatic system Main article: Lymphatic system
Lymphatic system
§ Function Clinical significance Many diseases affect the circulatory system. This includes cardiovascular disease, affecting the cardiovascular system, and lymphatic disease affecting the lymphatic system. Cardiologists are medical professionals which specialise in the heart, and cardiothoracic surgeons specialise in operating on the heart and its surrounding areas. Vascular surgeons focus on other parts of the circulatory system. Cardiovascular disease Main article: Cardiovascular disease Diseases affecting the cardiovascular system are called cardiovascular disease. Many of these diseases are called "lifestyle diseases" because they develop over time and are related to a person's exercise habits, diet, whether they smoke, and other lifestyle choices a person makes. Atherosclerosis
is the precursor to many of these diseases. It is where small atheromatous plaques build up in the walls of medium and large arteries. This may eventually grow or rupture to occlude the arteries. It is also a risk factor for acute coronary syndromes, which are diseases which are characterised by a sudden deficit of oxygenated blood to the heart tissue. Atherosclerosis
is also associated with problems such as aneurysm formation or splitting ("dissection") of arteries. Another major cardiovascular disease involves the creation of a clot, called a "thrombus". These can originate in veins or arteries. Deep venous thrombosis, which mostly occurs in the legs, is one cause of clots in the veins of the legs, particularly when a person has been stationary for a long time. These clots may embolise, meaning travel to another location in the body. The results of this may include pulmonary embolus, transient ischaemic attacks, or stroke. Cardiovascular diseases may also be congenital in nature, such as heart defects or persistent fetal circulation, where the circulatory changes that are supposed to happen after birth do not. Not all congenital changes to the circulatory system are associated with diseases, a large number are anatomical variations. Investigations

Magnetic resonance angiography
Magnetic resonance angiography
of aberrant subclavian artery

The function and health of the circulatory system and its parts are measured in a variety of manual and automated ways. These include simple methods such as those that are part of the cardiovascular examination, including the taking of a person's pulse as an indicator of a person's heart rate, the taking of blood pressure through a sphygmomanometer or the use of a stethoscope to listen to the heart for murmurs which may indicate problems with the heart's valves. An electrocardiogram can also be used to evaluate the way in which electricity is conducted through the heart. Other more invasive means can also be used. A cannula or catheter inserted into an artery may be used to measure pulse pressure or pulmonary wedge pressures. Angiography, which involves injecting a dye into an artery to visualise an arterial tree, can be used in the heart (coronary angiography) or brain. At the same time as the arteries are visualised, blockages or narrowings may be fixed through the insertion of stents, and active bleeds may be managed by the insertion of coils. An MRI may be used to image arteries, called an MRI angiogram. For evaluation of the blood supply to the lungs a CT pulmonary angiogram may be used. Vascular ultrasonography include for example:

Intravascular ultrasound Ultrasonography of deep venous thrombosis Ultrasonography of chronic venous insufficiency of the legs


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There are a number of surgical procedures performed on the circulatory system:

Coronary artery bypass surgery Coronary stent
Coronary stent
used in angioplasty Vascular surgery Vein
stripping Cosmetic procedures

Cardiovascular procedures are more likely to be performed in an inpatient setting than in an ambulatory care setting; in the United States, only 28% of cardiovascular surgeries were performed in the ambulatory care setting.[13] Society and culture

This section needs expansion. You can help by adding to it. (March 2015)

Other animals While humans, as well as other vertebrates, have a closed cardiovascular system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open cardiovascular system. The lymphatic system, on the other hand, is an open system providing an accessory route for excess interstitial fluid to be returned to the blood.[5] The more primitive, diploblastic animal phyla lack circulatory systems. The blood vascular system first appeared probably in an ancestor of the triploblasts over 600 million years ago, overcoming the time-distance constraints of diffusion, while endothelium evolved in an ancestral vertebrate some 540–510 million years ago.[14] Open circulatory system See also: Hemolymph

The open circulatory system of the grasshopper – made up of a heart, vessels and hemolymph. The hemolymph is pumped through the heart, into the aorta, dispersed into the head and throughout the hemocoel, then back through the ostia in the heart and the process repeated.

In arthropods, the open circulatory system is a system in which a fluid 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.[15] 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 sodium, chlorine, potassium, magnesium, and calcium), 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.

Flatworms, such as this Pseudoceros bifurcus, lack specialized circulatory organs

Closed circulatory system

Two-chambered heart of a fish

The circulatory systems of all vertebrates, as well as of annelids (for example, earthworms) and cephalopods (squids, octopuses and relatives) 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.[16] 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 cycle 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. In reptiles, the ventricular septum of the heart is incomplete and the pulmonary artery is equipped with a sphincter muscle. This allows a second possible route of blood flow. Instead of blood flowing through the pulmonary artery to the lungs, the sphincter may be contracted to divert this blood flow through the incomplete ventricular septum into the left ventricle and out through the aorta. This means the blood flows from the capillaries to the heart and back to the capillaries instead of to the lungs. This process is useful to ectothermic (cold-blooded) animals in the regulation of their body temperature. Birds, mammals, and crocodilians 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 and crocodilians evolved independently from that of mammals.[17]

No circulatory system Circulatory systems are absent in some animals, including flatworms. 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. Some animals, such as jellyfish, have more extensive branching from their gastrovascular cavity (which functions as both a place of digestion and a form of circulation), this branching allows for bodily fluids to reach the outer layers, since the digestion begins in the inner layers. History

Human anatomical chart of blood vessels, with heart, lungs, liver and kidneys included. Other organs are numbered and arranged around it. Before cutting out the figures on this page, Vesalius
suggests that readers glue the page onto parchment and gives instructions on how to assemble the pieces and paste the multilayered figure onto a base "muscle man" illustration. "Epitome", fol.14a. HMD Collection, WZ 240 V575dhZ 1543.

The earliest known writings on the circulatory system are found in the Ebers Papyrus
Ebers Papyrus
(16th century BCE), an ancient Egyptian medical papyrus containing over 700 prescriptions and remedies, both physical and spiritual. In the papyrus, it acknowledges the connection of the heart to the arteries. The Egyptians thought air came in through the mouth and into the lungs and heart. From the heart, the air travelled to every member through the arteries. Although this concept of the circulatory system is only partially correct, it represents one of the earliest accounts of scientific thought. In the 6th century BCE, the knowledge of circulation of vital fluids through the body was known to the Ayurvedic physician Sushruta
in ancient India.[18] He also seems to have possessed knowledge of the arteries, described as 'channels' by Dwivedi & Dwivedi (2007).[18] The valves of the heart were discovered by a physician of the Hippocratean school around the 4th century BCE. 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 Greek physician, Herophilus, distinguished veins from arteries but thought that the pulse was a property of arteries themselves. Greek anatomist 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.[19] In 2nd century AD Rome, the 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 1025, The Canon of Medicine
The Canon of Medicine
by the Persian physician, Avicenna, "erroneously accepted the Greek notion regarding the existence of a hole in the ventricular septum by which the blood traveled between the ventricles." Despite this, Avicenna
"correctly wrote on the cardiac cycles and valvular function", and "had a vision of blood circulation" in his Treatise on Pulse.[20][verification needed] While also refining Galen's erroneous theory of the pulse, Avicenna
provided the first correct explanation of pulsation: "Every beat of the pulse comprises two movements and two pauses. Thus, expansion : pause : contraction : pause. [...] The pulse is a movement in the heart and arteries ... which takes the form of alternate expansion and contraction."[21] In 1242, the Arabian physician, Ibn al-Nafis, became the first person to accurately describe the process of pulmonary circulation, for which he is sometimes considered the father of circulatory physiology.[22][not in citation given] Ibn al-Nafis
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..."

In addition, Ibn al-Nafis
Ibn al-Nafis
had an insight into what would become a larger theory of the capillary circulation. He stated that "there must be small communications or pores (manafidh in Arabic) between the pulmonary artery and vein," a prediction that preceded the discovery of the capillary system by more than 400 years.[23] Ibn al-Nafis' theory, however, was confined to blood transit in the lungs and did not extend to the entire body. Michael Servetus
Michael Servetus
was the first European to describe the function of pulmonary circulation, although his achievement was not widely recognized at the time, for a few reasons. He firstly described it in the "Manuscript of Paris"[24][25] (near 1546), but this work was never published. And later he published this description, but in a theological treatise, Christianismi Restitutio, not in a book on medicine. Only three copies of the book survived but these remained hidden for decades, the rest were burned shortly after its publication in 1553 because of persecution of Servetus by religious authorities. Better known discovery of pulmonary circulation was by Vesalius's successor at Padua, Realdo Colombo, in 1559.

Image of veins from William Harvey's Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus, 1628

Finally, William Harvey, a pupil of Hieronymus Fabricius
Hieronymus Fabricius
(who had earlier described the valves of the veins without recognizing their function), performed a sequence of experiments, and published Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus in 1628, which "demonstrated that there had to be a direct connection between the venous and arterial systems throughout the body, and not just the lungs. Most importantly, he argued that the beat of the heart produced a continuous circulation of blood through minute connections at the extremities of the body. This is a conceptual leap that was quite different from Ibn al-Nafis' refinement of the anatomy and bloodflow in the heart and lungs."[26] This work, with its essentially correct exposition, slowly convinced the medical world. However, Harvey was not able to identify the capillary system connecting arteries and veins; these were later discovered by Marcello Malpighi in 1661. In 1956, André Frédéric Cournand, Werner Forssmann
Werner Forssmann
and Dickinson W. Richards were awarded the Nobel Prize in Medicine "for their discoveries concerning heart catheterization and pathological changes in the circulatory system."[27] In his Nobel lecture, Forssmann credits Harvey as birthing cardiology with the publication of his book in 1628.[28] In the 1970s, Diana McSherry developed computer-based systems to create images of the circulatory system and heart without the need for surgery.[29] See also

Cardiology Vital heat Cardiac muscle Major systems of the human body Amato Lusitano Vascular resistance


^ "circulatory system" at Dorland's Medical Dictionary ^ "Let's beat cancer sooner". Cancer Research UK. Retrieved April 13, 2017.  ^ "cardiovascular system" at Dorland's Medical Dictionary ^ "How does the blood circulatory system work?". PubMed Health. 1 August 2016.  ^ a b Sherwood, Lauralee (2011). Human Physiology: From Cells to Systems. Cengage Learning. pp. 401–. ISBN 978-1-133-10893-1.  ^ Cardiovascular System at the US National Library of Medicine Medical Subject Headings (MeSH) ^ Pratt, Rebecca. "Cardiovascular System: Blood". AnatomyOne. Amirsys, Inc. Archived from the original on 2017-02-24.  ^ a b c d Guyton, Arthur; Hall, John (2000). Guyton Textbook of Medical Physiology (10 ed.). ISBN 072168677X.  ^ National Institutes of Health. "What Are the Lungs?". nih.gov. Archived from the original on 2014-10-04.  ^ State University of New York
State University of New York
(February 3, 2014). "The Circulatory System". suny.edu. Archived from the original on February 3, 2014.  ^ Alberts, B.; Johnson, A.; Lewis, J.; Raff, M.; Roberts, K.; Walters, P. (2002). Molecular Biology of the Cell (4th ed.). New York and London: Garland Science. ISBN 0-8153-3218-1.  ^ Whitaker, Kent (2001). "Fetal Circulation". Comprehensive Perinatal and Pediatric Respiratory Care. Delmar Thomson Learning. pp. 18–20. ISBN 978-0-7668-1373-1.  ^ Wier LM, Steiner CA, Owens PL (April 17, 2015). "Surgeries in Hospital-Owned Outpatient Facilities, 2012". HCUP Statistical Brief #188. Rockville, MD: Agency for Healthcare Research and Quality.  ^ Monahan‐Earley, R., Dvorak, A. M., & Aird, W. C. (2013). Evolutionary origins of the blood vascular system and endothelium. Journal of Thrombosis and Haemostasis 11 (s1): 46-66. ^ Bailey, Regina. "Circulatory System". biology.about.com.  ^ Simões-Costa MS, et al. 2005. The evolutionary origin of cardiac chambers. Dev. Biol. 277: 1–15. ^ "Crocodilian Hearts". National Center for Science Education. October 24, 2008. Retrieved October 3, 2015.  ^ a b Dwivedi, Girish & Dwivedi, Shridhar (2007). "History of Medicine: Sushruta – the Clinician – Teacher par Excellence" Archived October 10, 2008, at the Wayback Machine., Indian J Chest Dis Allied Sci Vol.49 pp.243-4, National Informatics Centre (Government of India). ^ Anatomy – History of anatomy. Scienceclarified.com. Retrieved 2013-09-15. ^ Shoja, M. M.; Tubbs, R. S.; Loukas, M.; Khalili, M.; Alakbarli, F.; Cohen-Gadol, A. A. (2009). "Vasovagal syncope in the Canon of Avicenna: The first mention of carotid artery hypersensitivity". International Journal of Cardiology. 134 (3): 297–301. doi:10.1016/j.ijcard.2009.02.035. PMID 19332359.  ^ Hajar, Rachel (1999). "The Greco-Islamic Pulse". Heart
Views. 1 (4): 136–140 [138]. Archived from the original on 2014-01-09.  ^ Reflections, Chairman's (2004). "Traditional Medicine Among Gulf Arabs, Part II: Blood-letting". Heart
Views. 5 (2): 74–85 [80]. Archived from the original on 2007-09-11.  ^ West, J. B. (2008). "Ibn al-Nafis, the pulmonary circulation, and the Islamic Golden Age". Journal of Applied Physiology. 105 (6): 1877–1880. doi:10.1152/japplphysiol.91171.2008. PMC 2612469 . PMID 18845773.  ^ Gonzalez Etxeberria, Patxi (2011) Amor a la verdad, el – vida y obra de Miguel servet [The love for truth. Life and work of Michael Servetus]. Navarro y Navarro, Zaragoza, collaboration with the Government of Navarra, Department of Institutional Relations and Education of the Government of Navarra. ISBN 8423532666 pp. 215–228 & 62nd illustration (XLVII) ^ Michael Servetus
Michael Servetus
Research Study with graphical proof on the Manuscript of Paris and many other manuscripts and new works by Servetus ^ Pormann, Peter E. and Smith, E. Savage (2007) Medieval Islamic medicine Georgetown University, Washington DC, p. 48, ISBN 1589011619. ^ "The Nobel Prize in Physiology or Medicine 1956". Nobel Foundation. Retrieved 2007-07-28.  ^ "The Role of Heart
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Library resources about Circulatory system

Resources in your library

http://cnx.org/content/m46646/latest/ The Circulatory System Reiber C. L. & McGaw I. J. (2009). "A Review of the "Open" and "Closed" Circulatory Systems: New Terminology for Complex Invertebrate Circulatory Systems in Light of Current Findings". International Journal of Zoology 2009: 8 pages. doi:10.1155/2009/301284. Patwardhan K. The history of the discovery of blood circulation: unrecognized contributions of Ayurveda
masters. Adv Physiol Educ. 2012 Jun;36(2):77–82. Michael Servetus
Michael Servetus
Research Study on the Manuscript of Paris by Servetus (1546 description of the Pulmonary Circulation)

v t e

Anatomy of the heart



base apex sulci

coronary interatrial anterior interventricular posterior interventricular


right left



interatrial septum pectinate muscles terminal sulcus


interventricular septum trabeculae carneae chordae tendineae papillary muscle

valves cusps atrioventricular septum

cardiac skeleton intervenous tubercle


Right heart

(venae cavae, coronary sinus) → right atrium (atrial appendage, fossa ovalis, limbus of fossa ovalis, crista terminalis, valve of inferior vena cava, valve of coronary sinus) → tricuspid valve → right ventricle (infundibulum, moderator band/septomarginal trabecula) → pulmonary valve → (pulmonary artery and pulmonary circulation)

Left heart

(pulmonary veins) → left atrium (atrial appendage) → mitral valve → left ventricle → aortic valve (aortic sinus) → (aorta and systemic circulation)



heart valves


Conduction system

cardiac pacemaker SA node Bachmann's bundle AV node bundle of His bundle branches Purkinje fibers

Pericardial cavity

pericardial sinus


fibrous pericardium

sternopericardial ligaments

serous pericardium

epicardium/visceral layer

fold of left vena cava


Circulatory system Coronary circulation Coronary arteries

v t e

and veins



Nutrient artery Arteriole


Elastic artery



Continuous Fenestrated Sinusoidal

Precapillary sphincter Precapillary resistance


Vena comitans Superficial vein Deep vein Emissary veins Venous plexus Venule


Lymphatic vessel Lymph Lymph

Circulatory system


Left heart
Left heart
→ Arterioles → Capillaries
→ Venules → Veins
Vena cava
Vena cava
→ (Right heart)


Right heart
Right heart
→ Pulmonary arteries → Lungs
Pulmonary vein
Pulmonary vein
→ Left heart


Microvessel Microcirculation Tunica intima

Endothelium Internal elastic lamina

Tunica media Tunica externa Vasa vasorum Vasa nervorum Vascular nerves Rete mirabile Circulatory anastomosis

v t e

Physiology of the cardiovascular system


Cardiac output

Cardiac cycle Cardiac output

rate Stroke


End-diastolic volume End-systolic volume

Afterload Preload Frank–Starling law Cardiac function curve Venous return curve Wiggers diagram Pressure
volume diagram


Fractional shortening = (End-diastolic dimension End-systolic dimension) / End-diastolic dimension Aortic valve
Aortic valve
area calculation Ejection fraction Cardiac index


Cardiac pacemaker Chronotropic ( Heart
rate) Dromotropic (Conduction velocity) Inotropic (Contractility) Bathmotropic (Excitability) Lusitropic (Relaxation)


Conduction system Cardiac electrophysiology Action potential

cardiac atrial ventricular

Effective refractory period Pacemaker potential Electrocardiography

P wave PR interval QRS complex QT interval ST segment T wave U wave

Hexaxial reference system

Chamber pressure

Central venous Right

atrial ventricular

pulmonary artery



atrial ventricular



Ventricular remodeling

Vascular system/ Hemodynamics


Compliance Vascular resistance Pulse Perfusion



Systolic Diastolic

Mean arterial pressure Jugular venous pressure Portal
venous pressure

Regulation of BP

Baroreflex Kinin–kallikrein system Renin–angiotensin system Vasoconstrictors Vasodilators Autoregulation

Myogenic mechanism Tubuloglomerular feedback Cerebral autoregulation


Aortic body Carotid body Glomus cell

v t e

Development of the circulatory system


Tubular heart

Truncus arteriosus Bulbus cordis Primitive ventricle Primitive atrium Sinus venosus

Chamber formation


Primary interventricular foramen Endocardial cushions Septum intermedium Atrioventricular canal


Septum primum Foramen secundum Primary interatrial foramen Septum secundum Foramen ovale


Aorticopulmonary septum Protein
signalling in heart development



Dorsal aorta Aortic arches Aortic sac


Anterior cardinal vein Posterior cardinal vein Common cardinal veins



Extraembryonic hemangiogenesis

islands Chorion Connecting stalk Yolk sac Placenta

Fetal circulation

umbilical cord: Umbilical vein
Umbilical vein
Ductus venosus
Ductus venosus
→ Inferior vena cava → Heart
Pulmonary artery
Pulmonary artery
Ductus arteriosus
Ductus arteriosus
→ Aorta → Umbilical artery

yolk sac: Vitelline veins Vitelline arteries

v t e

Cardiovascular disease
Cardiovascular disease
(heart) (I00–I52, 390–429)


Coronary disease

Coronary artery disease
Coronary artery disease
(CAD) Coronary artery aneurysm Spontaneous coronary artery dissection (SCAD) Coronary thrombosis Coronary vasospasm Myocardial bridge

Active ischemia

Angina pectoris

Prinzmetal's angina Stable angina

Acute coronary syndrome

Myocardial infarction Unstable angina



Hibernating myocardium Myocardial stunning


Myocardial rupture


of heart / Ventricular aneurysm Dressler syndrome




Acute Chronic / Constrictive

Pericardial effusion

Cardiac tamponade Hemopericardium



Chagas disease




Hypertrophic Restrictive Loeffler endocarditis Cardiac amyloidosis Endocardial fibroelastosis

Arrhythmogenic right ventricular dysplasia

/ valves


infective endocarditis

Subacute bacterial endocarditis

non-infective endocarditis

Libman–Sacks endocarditis Nonbacterial thrombotic endocarditis



regurgitation prolapse stenosis


stenosis insufficiency


stenosis insufficiency


stenosis insufficiency

Conduction / arrhythmia


Sinus bradycardia Sick sinus syndrome Heart
block: Sinoatrial AV

1° 2° 3°

Intraventricular Bundle branch block

Right Left Left anterior fascicle Left posterior fascicle Bifascicular Trifascicular

Adams–Stokes syndrome

Tachycardia (paroxysmal and sinus)





AV nodal reentrant Junctional ectopic


Accelerated idioventricular rhythm Catecholaminergic polymorphic Torsades de pointes

Premature contraction

Atrial Junctional Ventricular

Pre-excitation syndrome

Lown–Ganong–Levine Wolff–Parkinson–White

Flutter / fibrillation

Atrial flutter Ventricular flutter Atrial fibrillation


Ventricular fibrillation


Ectopic pacemaker / Ectopic beat Multifocal atrial tachycardia Pacemaker syndrome Parasystole Wandering pacemaker

Long QT syndrome

Andersen–Tawil Jervell and Lange-Nielsen Romano–Ward

Cardiac arrest

Sudden cardiac death Asystole Pulseless electrical activity Sinoatrial arrest

Other / ungrouped

hexaxial reference system

Right axis deviation Left axis deviation


Short QT syndrome


T wave
T wave


Osborn wave ST elevation ST depression

Strain pattern


Ventricular hypertrophy

Left Right / Cor pulmonale

Atrial enlargement

Left Right


Cardiac fibrosis Heart

Diastolic heart failure Cardiac asthma

Rheumatic fever

v t e

Human systems and organs


Skeletal system


Carpus Collar bone (clavicle) Thigh bone (femur) Fibula Humerus Mandible Metacarpus Metatarsus Ossicles Patella Phalanges Radius Skull Tarsus Tibia Ulna Rib Vertebra Pelvis Sternum



Fibrous joint Cartilaginous joint Synovial joint

Muscular system

Muscle Tendon Diaphragm

Circulatory system

Cardiovascular system


Artery Vein Lymphatic vessel


Lymphatic system


marrow Thymus


Spleen Lymph

CNS equivalent

Glymphatic system

Nervous system

Brain Spinal cord Nerve

Sensory system

Ear Eye

Integumentary system

Skin Subcutaneous tissue Breast

Mammary gland

Immune system


immune system


Lymphoid immune system

Respiratory system


Nose Nasopharynx Larynx


Trachea Bronchus Lung

Digestive system


Salivary gland Tongue

upper GI

Oropharynx Laryngopharynx Esophagus Stomach

lower GI

Small intestine Appendix Colon Rectum Anus


Liver Biliary tract Pancreas

Urinary system

Genitourinary system Kidney Ureter Bladder Urethra

Reproductive system


Uterus Vagina Vulva Ovary Placenta


Scrotum Penis Prostate Testicle Seminal vesicle

Endocrine system

Pituitary Pineal Thyroid Parathyroid Adrenal Islets of Langerhans

v t e

Diving medicine, physiology, physics and environment

Diving medicine

Injuries and disorders



Freediving blackout Hyperoxia Hypoxia (medical) Oxygen

Inert gases

Atrial septal defect Avascular necrosis Decompression sickness Dysbaric osteonecrosis High-pressure nervous syndrome Hydrogen narcosis Isobaric counterdiffusion Nitrogen narcosis Taravana Uncontrolled decompression

Carbon dioxide

Hypercapnia Hypocapnia

Aerosinusitis Air embolism Alternobaric vertigo Barodontalgia Barostriction Barotrauma Compression arthralgia Decompression illness Dental barotrauma Dysbarism Ear
clearing Frenzel maneuver Valsalva maneuver


Asphyxia Drowning Hypothermia Immersion diuresis Instinctive drowning response Laryngospasm Salt water aspiration syndrome Swimming-induced pulmonary edema

List of signs and symptoms of diving disorders Cramps Diving disorders Motion sickness Surfer's ear


Diving chamber Diving medicine Hyperbaric medicine Hyperbaric treatment schedules In-water recompression Oxygen

Fitness to dive

Diving physiology

Artificial gills (human) Blood–air barrier Blood
shift Breathing Circulatory system CO₂ retention Cold shock response Dead space (physiology) Decompression (diving) Decompression theory Diving reflex Gas exchange History of decompression research and development Lipid Maximum operating depth Metabolism Normocapnia Oxygen
window in diving decompression Perfusion Physiological response to water immersion Physiology of decompression Pulmonary circulation Respiratory exchange ratio Respiratory quotient Respiratory system Systemic circulation Tissue (biology)

Diving physics

Ambient pressure Amontons' law Anti-fog Archimedes' principle Atmospheric pressure Boyle's law Breathing
performance of regulators Buoyancy Charles's law Combined gas law Dalton's law Diffusion Force Gay-Lussac's law Henry's law Hydrophobe Hydrostatic pressure Ideal gas law Molecular diffusion Neutral buoyancy Oxygen
fraction Partial pressure Permeation Pressure Psychrometric constant Snell's law Solubility Solution Supersaturation Surface tension Surfactant Torricellian chamber Underwater vision Weight

Diving environment

Algal bloom Breaking wave Ocean current Current (stream) Ekman transport Halocline List of diving hazards and precautions Longshore drift Rip current Stratification Surf Surge (wave action) Thermocline Tides Turbidity Undertow (water waves) Upwelling

Researchers in diving medicine and physiology

Arthur J. Bachrach Albert R. Behnke Paul Bert George F. Bond Robert Boyle Albert A. Bühlmann John R Clarke William Paul Fife John Scott Haldane Robert William Hamilton Jr. Leonard Erskine Hill Brian Andrew Hills Felix Hoppe-Seyler Christian J. Lambertsen Simon Mitchell Charles Momsen John Rawlins R.N. Charles Wesley Shilling Edward D. Thalmann Jules Triger

Diving medical research organisations

Aerospace Medical Association Divers Alert Network
Divers Alert Network
(DAN) Diving Diseases Research Centre
Diving Diseases Research Centre
(DDRC) Diving Medical Advisory Council (DMAC European Diving Technology Committee
European Diving Technology Committee
(EDTC) European Underwater and Baromedical Society
European Underwater and Baromedical Society
(EUBS) National Board of Diving and Hyperbaric Medical Technology Naval Submarine Medical Research Laboratory Royal Australian Navy School of Underwater Medicine Rubicon Foundation South Pacific Underwater Medicine Society
South Pacific Underwater Medicine Society
(SPUMS) Southern African Underwater and Hyperbaric Medical Association
Southern African Underwater and Hyperbaric Medical Association

Undersea and Hyperbaric Medical Society
Undersea and Hyperbaric Medical Society
(UHMS) United States Navy Experimental Diving Unit
United States Navy Experimental Diving Unit

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