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":

Echocardiography
... Echocardiogram, often referred to cardiac echo or simply an echo is a sonogram of the heart ... two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart ... used in the diagnosis, management, and follow-up of patients with any suspected or known heart diseases ...
Digoxin - Pharmacokinetic Properties
... 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 ...
Digoxin - Mechanism of Action
... on the extracellular 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 ... This leads to increased contractility (the force of contraction) of the heart without increasing heart energy expenditure ...
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 ... 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 the precious relic was lost ...
Heart Valve
... A heart valve normally allows blood flow in only one direction through the heart ... A heart valve opens or closes incumbent upon differential blood pressure on each side ... The four valves in the heart are The two atrioventricular (AV) valves, which are between the atria and the ventricles, are the mitral valve and the tricuspid valve ...

Famous quotes containing the word heart:

    When I was one-and-twenty
    I heard a wise man say,
    “Give crowns and pounds and guineas
    But not your heart away;
    —A.E. (Alfred Edward)

    Lady Dellwyn ... for the first time began to entertain some suspicions that she had a heart to bestow. Not that she was actuated by that romantic passion which creates indifference to every other object and makes all happiness to consist in pleasing the beloved person, [but] only overstraining delicacy so much as to feel it almost a crime to charm any other.
    Sarah Fielding (1710–1768)

    They flash upon that inward eye
    Which is the bliss of solitude;
    And then my heart with pleasure fills,
    And dances with the daffodils.
    William Wordsworth (1770–1850)