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 ...
... Echocardiogram, often referred to cardiac echo or simply an echo is a sonogram of the heart ... Doppler ultrasound to create images of the heart ... and follow-up of patients with any suspected or known heart diseases ...
... “Talk of strange relics led to mention of the heart of a French King preserved at Nuneham in a silver casket ... 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 for ever.” The heart in question ...
... aspect of the α-subunit of the Na+/K+ ATPase pump in the membranes of heart cells (myocytes) and decreases its function ... lengthens phase 4 and phase 0 of the cardiac action potential, which leads to a decrease in heart rate ... contractility (the force of contraction) of the heart without increasing heart energy expenditure ...
... 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 ...
Famous quotes containing the word heart:
“One enemy, of many, who knows well
Your heart is luminous
In the watched dark, quivering through locks and caves,
Will pull the thunderbolts
To shut the sun, plunge, mount your darkened keys....”
—Dylan Thomas (19141953)
“Do not give heed to everything that people say, or you may hear your servant cursing you; your heart knows that many times you have yourself cursed others.”
—Bible: Hebrew, Ecclesiastes 7:21.
“He has outsoared the shadow of our night;
Envy and calumny and hate and pain,
And that unrest which men miscall delight,
Can touch him not and torture not again;
From the contagion of the worlds slow stain
He is secure, and now can never mourn
A heart grown cold, a head grown grey in vain.”
—Percy Bysshe Shelley (17921822)