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Visit the American Heart Association website to help locate a course near your home in the United States. There are also many other national and regional heart associations that offer the same service, depending upon the location.

Shape and size of the heart

The shape of the heart is similar to a pinecone, rather broad at the superior surface and tapering to the apex (see [link] ). A typical heart is approximately the size of your fist: 12 cm (5 in) in length, 8 cm (3.5 in) wide, and 6 cm (2.5 in) in thickness. Given the size difference between most members of the sexes, the weight of a female heart is approximately 250–300 grams (9 to 11 ounces), and the weight of a male heart is approximately 300–350 grams (11 to 12 ounces). The heart of a well-trained athlete, especially one specializing in aerobic sports, can be considerably larger than this. Cardiac muscle responds to exercise in a manner similar to that of skeletal muscle. That is, exercise results in the addition of protein myofilaments that increase the size of the individual cells without increasing their numbers, a concept called hypertrophy. Hearts of athletes can pump blood more effectively at lower rates than those of nonathletes. Enlarged hearts are not always a result of exercise; they can result from pathologies, such as hypertrophic cardiomyopathy    . The cause of an abnormally enlarged heart muscle is unknown, but the condition is often undiagnosed and can cause sudden death in apparently otherwise healthy young people.

Chambers and circulation through the heart

The human heart consists of four chambers: The left side and the right side each have one atrium    and one ventricle    . Each of the upper chambers, the right atrium (plural = atria) and the left atrium, acts as a receiving chamber and contracts to push blood into the lower chambers, the right ventricle and the left ventricle. The ventricles serve as the primary pumping chambers of the heart, propelling blood to the lungs or to the rest of the body.

There are two distinct but linked circuits in the human circulation called the pulmonary and systemic circuits. Although both circuits transport blood and everything it carries, we can initially view the circuits from the point of view of gases. The pulmonary circuit    transports blood to and from the lungs, where it picks up oxygen and delivers carbon dioxide for exhalation. The systemic circuit    transports oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation.

The right ventricle pumps deoxygenated blood into the pulmonary trunk    , which leads toward the lungs and bifurcates into the left and right pulmonary arteries    . These vessels in turn branch many times before reaching the pulmonary capillaries    , where gas exchange occurs: Carbon dioxide exits the blood and oxygen enters. The pulmonary trunk arteries and their branches are the only arteries in the post-natal body that carry relatively deoxygenated blood. Highly oxygenated blood returning from the pulmonary capillaries in the lungs passes through a series of vessels that join together to form the pulmonary veins    —the only post-natal veins in the body that carry highly oxygenated blood. The pulmonary veins conduct blood into the left atrium, which pumps the blood into the left ventricle, which in turn pumps oxygenated blood into the aorta and on to the many branches of the systemic circuit. Eventually, these vessels will lead to the systemic capillaries, where exchange with the tissue fluid and cells of the body occurs. In this case, oxygen and nutrients exit the systemic capillaries to be used by the cells in their metabolic processes, and carbon dioxide and waste products will enter the blood.

Questions & Answers

what is systemic anatomy
Friday Reply
it's a study of organ structure
Amarachi
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Ujam
what happened when they are badly severed
Ujam
Examples of glial cells?
Nesh Reply
glial cell s help in the attractive foces of motion in the cellular network
Ujam
What is glial cell?
Esther
what is homeostasis
Laura Reply
homeostasis- The ability to maintain relatively stable internal conditions even though the outside world changes continuously. i,e, maintaining normal values in your body such as Adequate blood levels,blood pressure, heart activity and blood pressure.
Williams
thank you
Laura
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It helps to know about the body structure properly and administer proper care for the patient
Opeyemi
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augmentin is a type of combination antibiotic.
wintana
Can you explain to Heart anatomy in details please?
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definition of anatomy and physiology
Sardar Reply
Anatomy is the study structure of the body while physiology is the study of function of the body
Ayan
What is a dorsal cavity?
John Reply
Explain in detail mitosis and meiosis
sedeck Reply
What is Sodium Potassium Pump?
Mwamba Reply
The process of moving sodium and potassium ions across the cell membrance is an active transport process involving the hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na+/K+-ATPase
USAMA
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Carlos
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Esther Reply
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Hridy Reply
I think it's the study of the internal and external features of the body and its physical relationship between body parts
Esther
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Sardar
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mahamed Reply
Yeah, when there is a blockage in the bilary system( bile ducts) which lead to obstruction of the bile pigments called bilirubin leading to a characteristically yellowish appearance of the eyes.
ibrahim
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mahamed
there are three main resons why bilirubin levels in the blood may rise: 1. pre-hepatic jaundice,2. hepatic jaundice, 3. post hepatic
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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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