Heart

This article is about the internal organ. For other uses, see Heart (disambiguation).
"Cardiac" redirects here. For the computer programming tool, see CARDIAC. For the comics character, see Cardiac (character).

Heart
The human heart
Details
SystemCirculatory
ArteryAorta,[a] pulmonary trunk and right and left pulmonary arteries,[b] right coronary artery, left main coronary artery[c]
VeinSuperior vena cava, inferior vena cava,[d] right and left pulmonary veins,[e] great cardiac vein, middle cardiac vein, small cardiac vein, anterior cardiac veins[f]
NerveAccelerans nerve, vagus nerve
Identifiers
Latincor
Greekκαρδία (kardía)
MeSHD006321
Anatomical terminology

The heart is a muscular organ found in most animals. This organ pumps blood through the blood vessels.[1] Heart and blood vessels together make the circulatory system.[2] The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs.[3] In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest, called the mediastinum.[4]

In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles.[5][6] Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart.[7] Fish, in contrast, have two chambers, an atrium and a ventricle, while most reptiles have three chambers.[6] In a healthy heart, blood flows one way through the heart due to heart valves, which prevent backflow.[4] The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium.[8] In all vertebrates, the heart has an asymmetric orientation, almost always on the left side. According to one theory, this is caused by a developmental axial twist in the early embryo.[9][10]

The heart pumps blood with a rhythm determined by a group of pacemaker cells in the sinoatrial node. These generate an electric current that causes the heart to contract, traveling through the atrioventricular node and along the conduction system of the heart. In humans, deoxygenated blood enters the heart through the right atrium from the superior and inferior venae cavae and passes to the right ventricle. From here, it is pumped into pulmonary circulation to the lungs, where it receives oxygen and gives off carbon dioxide. Oxygenated blood then returns to the left atrium, passes through the left ventricle and is pumped out through the aorta into systemic circulation, traveling through arteries, arterioles, and capillaries—where nutrients and other substances are exchanged between blood vessels and cells, losing oxygen and gaining carbon dioxide—before being returned to the heart through venules and veins.[11] The heart beats at a resting rate close to 72 beats per minute.[12] Exercise temporarily increases the rate, but lowers it in the long term, and is good for heart health.[13]

Cardiovascular diseases are the most common cause of death globally as of 2008, accounting for 30% of all human deaths.[14][15] Of these more than three-quarters are a result of coronary artery disease and stroke.[14] Risk factors include: smoking, being overweight, little exercise, high cholesterol, high blood pressure, and poorly controlled diabetes, among others.[16] Cardiovascular diseases do not frequently have symptoms but may cause chest pain or shortness of breath. Diagnosis of heart disease is often done by the taking of a medical history, listening to the heart-sounds with a stethoscope, as well as with ECG, and echocardiogram which uses ultrasound.[4] Specialists who focus on diseases of the heart are called cardiologists, although many specialties of medicine may be involved in treatment.[15]

A teenager's heartbeat
Sounds of a healthy 16-year-old child's heart beating normally, as heard with a stethoscope.
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Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).

  1. ^ Moran, Michael E. (26 August 2013), "Gray's Anatomy of Stones: Henry Vandyke Carter", Urolithiasis, New York, NY: Springer New York, pp. 131–144, ISBN 978-1-4614-8195-9, retrieved 5 October 2024
  2. ^ Taber, Clarence Wilbur; Venes, Donald (2009). Taber's cyclopedic medical dictionary. F.A. Davis Co. pp. 1018–1023. ISBN 978-0-8036-1559-5.
  3. ^ Guyton & Hall 2011, p. 157.
  4. ^ a b c Moore, Keith L.; Dalley, Arthur F.; Agur, Anne M.R. (2009). "1". Clinically Oriented Anatomy. Wolters Kluwel Health/Lippincott Williams & Wilkins. pp. 127–173. ISBN 978-1-60547-652-0.
  5. ^ Starr, Cecie; Evers, Christine; Starr, Lisa (2009). Biology: Today and Tomorrow With Physiology. Cengage Learning. p. 422. ISBN 978-0-495-56157-6. Archived from the original on 2 May 2016.
  6. ^ a b Reed, C. Roebuck; Brainerd, Lee Wherry; Lee, Rodney; Kaplan, Inc. (2008). CSET : California Subject Examinations for Teachers (3rd ed.). New York: Kaplan Pub. p. 154. ISBN 978-1-4195-5281-6. Archived from the original on 4 May 2016.
  7. ^ Gray's Anatomy 2008, p. 960.
  8. ^ Betts, J. Gordon (2013). Anatomy & physiology. OpenStax College, Rice University. pp. 787–846. ISBN 978-1-938168-13-0. Archived from the original on 27 February 2021. Retrieved 11 August 2014.
  9. ^ de Lussanet, Marc H.E.; Osse, Jan W.M. (2012). "An ancestral axial twist explains the contralateral forebrain and the optic chiasm in vertebrates". Animal Biology. 62 (2): 193–216. arXiv:1003.1872. doi:10.1163/157075611X617102. ISSN 1570-7555. S2CID 7399128.
  10. ^ de Lussanet, M.H.E. (2019). "Opposite asymmetries of face and trunk and of kissing and hugging, as predicted by the axial twist hypothesis". PeerJ. 7: e7096. doi:10.7717/peerj.7096. PMC 6557252. PMID 31211022.
  11. ^ Guyton & Hall 2011, pp. 101, 157–158, 180.
  12. ^ Guyton & Hall 2011, pp. 105–107.
  13. ^ Guyton & Hall 2011, pp. 1039–1041.
  14. ^ a b "Cardiovascular diseases (CVDs) Fact sheet N°317 March 2013". WHO. World Health Organization. Archived from the original on 19 September 2014. Retrieved 20 September 2014.
  15. ^ a b Longo, Dan; Fauci, Anthony; Kasper, Dennis; Hauser, Stephen; Jameson, J.; Loscalzo, Joseph (2011). Harrison's Principles of Internal Medicine (18th ed.). McGraw-Hill Professional. p. 1811. ISBN 978-0-07-174889-6.
  16. ^ Graham, I; Atar, D; Borch-Johnsen, K; Boysen, G; Burell, G; Cifkova, R; Dallongeville, J; De Backer, G; Ebrahim, S; Gjelsvik, B; Herrmann-Lingen, C; Hoes, A; Humphries, S; Knapton, M; Perk, J; Priori, SG; Pyorala, K; Reiner, Z; Ruilope, L; Sans-Menendez, S; Scholte op Reimer, W; Weissberg, P; Wood, D; Yarnell, J; Zamorano, JL; Walma, E; Fitzgerald, T; Cooney, MT; Dudina, A; European Society of Cardiology (ESC) Committee for Practice Guidelines, (CPG) (October 2007). "European guidelines on cardiovascular disease prevention in clinical practice: executive summary: Fourth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (Constituted by representatives of nine societies and by invited experts)" (PDF). European Heart Journal. 28 (19): 2375–2414. doi:10.1093/eurheartj/ehm316. PMID 17726041. Archived (PDF) from the original on 27 April 2019. Retrieved 21 October 2019.