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":

... often referred to cardiac echo or simply an echo is a sonogram of the heart ... uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart ... management, and follow-up of patients with any suspected or known heart diseases ...
Digoxin - Pharmacokinetic Properties
... but can also be given by IV injection in urgent situations (the IV injection should be slow, and heart rhythm should be monitored) ... For congestive heart failure, levels between 0.5 and 1.0 ng/ml are recommended ... For heart rate control (atrial fibrillation), plasma levels are less defined and are generally titrated to a goal heart rate ...
Heart Valve
... A heart valve normally allows blood flow in only one direction through the heart ... The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart ... A heart valve opens or closes incumbent upon differential blood pressure on each side ...
Digoxin - Mechanism of Action
... aspect of the α-subunit of the Na+/K+ ATPase pump in the membranes of heart cells (myocytes) and decreases its function ... phase 4 and phase 0 of the cardiac action potential, which leads to a decrease in heart rate ... (the force of contraction) of the heart without increasing heart energy expenditure ...
William Buckland - Megalosaurus and Marriage
... of strange relics led to mention of the heart of a French King preserved at Nuneham in a silver casket ... at it, exclaimed, ‘I have eaten many strange things, but have never eaten the heart of a king before,’ and, before anyone could hinder him, he had gobbled it up ...

Famous quotes containing the word heart:

    Good-bye, good luck, struck the sun and the moon,
    To the fisherman lost on the land.
    He stands alone at the door of his home,
    With his long-legged heart in his hand.
    Dylan Thomas (1914–1953)

    To revolutionize, at one effort, the universal world of human thought, human opinion, and human sentiment.... All that he has to do is to write and publish a very little book. Its title should be simple—a few plain words—”My Heart Laid Bare.” But—this little book must be true to its title.
    Edgar Allan Poe (1809–1849)

    O heart the winds have shaken, the unappeasable host
    Is comelier than candles at Mother Mary’s feet.
    William Butler Yeats (1865–1939)