Heart
Overview
 
The heart is a myogenic muscular
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 organ
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...

 found in all animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s with a circulatory system
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...

 (including all vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s), that is responsible for pumping blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 throughout the blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

s by repeated, rhythmic contractions. The term cardiac (as in cardiology
Cardiology
Cardiology is a medical specialty dealing with disorders of the heart . The field includes diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology...

) means "related to the heart" and comes from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 καρδιά, kardia, for "heart".

The vertebrate heart is composed of cardiac muscle
Cardiac muscle
Cardiac muscle is a type of involuntary striated muscle found in the walls and histologic foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle...

, which is an involuntary striated muscle tissue found only in this organ, and connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

.
Quotations

It is the heart that carries one to heaven.

Anonymous proverb, as quoted in "The Mind of the African Negro as reflected in his Proverbs" in The Journal of Negro History, Volume 1 (1916), edited by Carter Godwin Woodson

"All the same," said the Scarecrow, "I shall ask for brains instead of a heart; for a fool would not know what to do with a heart if he had one."

L. Frank Baum, The Wonderful Wizard of Oz

"I shall take the heart," returned the Tin Woodman; "for brains do not make one happy, and happiness is the best thing in the world."

L. Frank Baum, The Wonderful Wizard of Oz

All these things shall love do unto you that you may know the secrets of your heart, and in that knowledge become a fragment of Life's heart. But if in your fear you would seek only love's peace and love's pleasure, Then it is better for you that you cover your nakedness and pass out of love's threshing floor, Into the seasonless world where you shall laugh, but not all of your laughter, and weep, but not all of your tears.

Khalil Gibran, The Prophet

"You should respect other religions....the essence of all religions is basically the same: to achieve a true sense of brotherhood, a good heart, respect for others. If we can develop these qualities from within our heart, then I think we can actually achieve true peace."

Tenzin Gyatso, 14th Dalai Lama

Liberty lies in the hearts of men and women; when it dies there, no constitution, no law, no court can save it.

Learned Hand, in "The Spirit of Liberty" - a speech at "I Am an American Day" ceremony, Central Park, New York City (21 May 1944)

The heart is deceitful above all things, and desperately wicked: who can know it?.

Jeremiah|Jeremiah 17:9 (Authorized King James Version|KJV)

The only business of the head in the world is to bow a ceaseless obediance to the heart.

William Butler Yeats

 
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