Heart

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 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 ...
Echocardiography
... often referred to cardiac echo or simply an echo is a sonogram of the heart ... and Doppler ultrasound to create images of the heart ... of patients with any suspected or known heart diseases ...
William Buckland - Megalosaurus and Marriage
... “Talk of strange relics led to mention of the heart of a French King preserved at Nuneham in a silver casket ... 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, and the ...
Digoxin - Mechanism of Action
... extracellular aspect of the α-subunit of the Na+/K+ ATPase pump in the membranes of heart cells (myocytes) and decreases its function ... and phase 0 of the cardiac action potential, which leads to a decrease in heart rate ... This leads to increased contractility (the force of contraction) of the heart without increasing heart energy expenditure ...

Famous quotes containing the word heart:

    For the sword outwears its sheath,
    And the soul wears out the breast.
    And the heart must pause to breathe,
    And love itself have rest.
    George Gordon Noel Byron (1788–1824)

    It is not worth the while to let our imperfections disturb us always. The conscience really does not, and ought not to monopolize the whole of our lives, any more than the heart or the head. It is as liable to disease as any other part.
    Henry David Thoreau (1817–1862)

    It is unconscionable that we ration health care by the ability to pay.... your heart breaks. Health care should be a given.
    Kathryn Anastos (b. 1950)