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.
Other articles related to "heart":
... 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 ...
... to cardiac echo or simply an echo is a sonogram of the heart ... 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 ...
... 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 ...
... 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, and ...
... 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 ... (the force of contraction) of the heart without increasing heart energy expenditure ...
Famous quotes containing the word heart:
“Jean Jacques Rousseau ... is nothing but a fool in my eyes when he takes it upon himself to criticise society; he did not understand it, and approached it with the heart of an upstart flunkey.... For all his preaching a Republic and the overthrow of monarchical titles, the upstart is mad with joy if a Duke alters the course of his after-dinner stroll to accompany one of his friends.”
—Stendhal [Marie Henri Beyle] (17831842)
“Tis not to see the world
As from a height, with rapt prophetic eyes,
And heart profoundly stirred;
And weep, and feel the fullness of the past,
The years that are not more.”
—Matthew Arnold (18221888)
“His form is fixed in my eyes,
his touch in my limbs,
his whispers in my ear,
and his heart is kept in my heart.
So what can Fate tear in two?”
—Hla Stavhana (c. 50 A.D.)