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":
... but can also 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 ...
... or simply an echo is a sonogram of the heart ... three-dimensional, and Doppler ultrasound to create images of the heart ... diagnosis, management, and follow-up of patients with any suspected or known heart diseases ...
... 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 ...
... of the Na+/K+ ATPase pump in the membranes of heart cells (myocytes) and decreases its function ... potential, which leads to a decrease in heart rate ... to increased contractility (the force of contraction) of the heart without increasing heart energy expenditure ...
... 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 ...
Famous quotes containing the word heart:
“He prayed more deeply for simple selflessness than he had ever prayed beforeand, feeling an uprush of grace in the very intention, shed the night in his heart and called it light. And walking out of the little church he felt confirmed in not only the worth of his whispered prayer but in the realization, as well, that Christ had become man and not some bell-shaped Corinthian column with volutes for veins and a mandala of stone foliage for a heart.”
—Alexander Theroux (b. 1940)
“Twelve oclock! It is the natural centre, key-stone, and very heart of the day. At that hour, the sun has arrived at the top of his hill; and as he seems to hang poised there a while, before coming down on the other side, it is but reasonable to suppose that he is then stopping to dine; setting an eminent example to all mankind.”
—Herman Melville (18191891)
“The Danube to the Severn gave
The darkend heart that beat no more;
They laid him by the pleasant shore,
And in the hearing of the wave.”
—Alfred Tennyson (18091892)