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":

William Buckland - Megalosaurus and Marriage
... English raconteur and contemporary, recalled, “Talk 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 ...
Echocardiography
... Echocardiogram, often referred to cardiac echo or simply an echo is a sonogram of the heart ... 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 - 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 ... lengthens phase 4 and phase 0 of the cardiac action potential, which leads to a decrease in heart rate ... leads to increased contractility (the force of contraction) of the heart without increasing heart energy expenditure ...
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 - Pharmacokinetic Properties
... 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 ...

Famous quotes containing the word heart:

    I cannot find language of sufficient energy to convey my sense of the sacredness of private integrity. All men, all things, the state, the church, yea the friends of the heart are phantasms and unreal beside the sanctuary of the heart. With so much awe, with so much fear, let it be respected.
    Ralph Waldo Emerson (1803–1882)

    The hapless Nymph with wonder saw:
    A whisker first and then a claw,
    With many an ardent wish,
    She stretch’d in vain to reach the prize.
    What female heart can gold despise?
    What Cat’s averse to fish?
    Thomas Gray (1716–1771)

    Weather abroad
    and weather in the heart alike come on
    Regardless of prediction.
    Adrienne Rich (b. 1929)