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":

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 ... action potential, which leads to a decrease in heart rate ... 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
... 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 ...
Echocardiography
... 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 ... routinely used in the diagnosis, management, and follow-up 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 ... looking 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, and ...

Famous quotes containing the word heart:

    If we may believe our logicians, man is distinguished from all other creatures by the faculty of laughter. He has a heart capable of mirth, and naturally disposed to it.
    Joseph Addison (1672–1719)

    ... the deep experience of the lonely climb on the mountain of success brings a wealth beyond power to compute. To you all suffering is understandable and your heart opens wide in sympathy.
    Alice Foote MacDougall (1867–1945)

    What of the heart without her? Nay, poor heart,
    Of thee what word remains ere speech be still?
    A wayfarer by barren ways and chill,
    Steep ways and weary, without her thou art,
    Where the long cloud, the long wood’s counterpart,
    Sheds doubled darkness up the labouring hill.
    Dante Gabriel Rossetti (1828–1882)