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":
... 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 ...
... 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 ... and follow-up of patients with any suspected or known heart diseases ...
... site 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 ...
... 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 ...
... and contemporary, recalled, “Talk of strange relics led to mention of the heart of a French King preserved at Nuneham in a silver casket ... 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:
“The last time I saw Paris
Her heart was warm and gay,
I heard the laughter of her heart in every street café.”
—Oscar Hammerstein II (18951960)
“Way down upon de Swanee ribber,
Far, far away,
Deres where my heart is turning ebber,
Deres where de old folks stay.”
—Stephen Collins Foster (18261884)
“Ive looked on a lot of women with lust. Ive committed adultery in my heart many times. This is something God recognizes I will doand I have done itand God forgives me for it.”
—Jimmy Carter (James Earl Carter, Jr.)