The heart is a hollow muscle that pumps blood throughout the blood vessels by repeated, rhythmic contractions. It is found in all animals with a circulatory system (including all vertebrates).
The term cardiac (as in cardiology) means "related to the heart" and comes from the Greek καρδιά, kardia, for "heart".
The vertebrate heart is principally composed of cardiac muscle and connective tissue. Cardiac muscle is an involuntary striated muscle tissue found only in this organ and responsible for the ability of the heart to pump blood.
The average human heart, beating at 72 beats per minute, will beat approximately 2.5 billion times during an average 66 year lifespan. It weighs approximately 250 to 300 grams (9 to 11 oz) in females and 300 to 350 grams (11 to 12 oz) in males.
Read more about Heart: Structure, The Invertebrate Heart, Functioning, Early Development, History of Discoveries, Additional Images
Other articles related to "heart, heart muscle":
... Heart failure is caused by any condition which reduces the efficiency of the myocardium, or heart muscle, through damage or overloading ... an array of conditions as myocardial infarction (in which the heart muscle is starved of oxygen and dies), hypertension (which increases the force of contraction needed to pump ... increases in workload will produce changes to the heart itself Reduced force of contraction, due to overloading of the ventricle ...
... circulation is the circulation of blood in the blood vessels of the heart muscle (myocardium) ... The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins ... The coronary arteries that run on the surface of the heart are called epicardial coronary arteries ...
... in reference to various drugs that affect the strength of contraction of heart muscle (myocardial contractility) ... For example, enlarged heart muscle (ventricular hypertrophy) can increase inotropic state, whereas dead heart muscle (myocardial infarction) can decrease it ...
Famous quotes containing the word heart:
“My dear, my dear, I know
More than another
What makes your heart beat so;
Not even your own mother
Can know it as I know,
Who broke my heart for her....”
—William Butler Yeats (1865–1939)