An organ consisting of the right atrium, right ventricle, left atrium, and left ventricle. Non-oxygenated blood enters the heart through the precava and postcava (large veins from the rest of the body) and oxygenated blood leaves through the aorta. Pulmonary arteries and veins carry the blood over the lungs in order for it to become oxygenated and recycled through the body.

If you have ever held a heart in your hand (the closest I have ever come is a cat's heart during Biology class), you will know that it is a beautiful, perfect, powerful thing.

Symbolic location of one's empathy, love, & compassion. When healthy, it moves us to proaction.

Anatomy of the human heart

The heart is a big muscular pump that operates throughout life, pumping blood through the body's dual circulation (pulmonary and systemic). It lies in the mediastinum in the chest, sort of between the anterior chest wall and the lungs.

The human heart is surrounded by a thin layer of tissue known as the pericardium and the space between the heart and pericardium is filled with a small amount of pericardial fluid. The human heart is made up of four chambers. The right atrium receives deoxygenated blood from the body via the superior vena cava and the inferior vena cava. This blood passes to the right ventricle, where it is pumped out along the pulmonary arteries to the lungs. Oxygenated blood returns to the heart from the lungs via the pulmonary veins which end in the left atrium. This blood is pumped to the left ventricle and is then pumped into the systemic circulation through the aorta.

In the normal heart, the walls of the ventricles are thicker than those of the atria and the wall of the left ventricle is thicker than the wall of the right ventricle (the left ventricle must pump blood to the entire body).

There are four valves in the heart. The tricuspid valve separates the right atrium from the right ventricle. The pulmonary valve prevents backflow from the pulmonary artery into the right ventricle. The mitral valve (also known as the bicuspid valve) separates the left atrium from the left ventricle. Finally, the aortic valve prevents backflow of blood from the aorta into the left ventricle and therefore helps keep the systemic blood pressure up.

A continuous septum separates the left and right atria and the left and right ventricles.

Blood supply to the heart arises via two blood vessels that branch off early from the aorta, namely the left coronary artery and the right coronary artery. The left coronary artery branches into the left anterior descending artery and the left circumflex artery. The right coronary artery sends an important branch to the SA node in the right atrium. Occasionally, anatomical variants of the coronary arteries are found and these can vary quite widely in pattern.

The heart is innervated by autonomic fibres, both sympathetic and parasympathetic (from the vagus nerve) and is also affected by the volume of venous return to the heart and to hormones such as adrenaline.

Part of the human anatomy project.

ASCII Art diagram of the human heart:

          |  \ \ | |/ /
          |  |\ `' ' /
          |  ;'aorta \      / , pulmonary arteries
          | ;    _,   |    / / ,
 superior | |   (  `-.;_,-' '-' ,
vena cava | `,   `-._       _,-'_
          |,-`.    `.)    ,<_,-'_, pulmonary veins
         ,'    `.   /   ,'  `;-' _,
        ;        `./   /`,    \-'
        | right   /   |  ;\   |\
        | atrium ;_,._|_,  `, ' \
        |        \    \ `       `,
        `      __ `    \   left  ;,
         \   ,'  `      \,  ventricle
          \_(            ;,      ;;
          |  \           `;,     ;;
 inferior |  |`.          `;;,   ;'
vena cava |  |  `-.        ;;;;,;'
          |  |    |`-.._  ,;;;;;'
          |  |    |   | ``';;;'  FL

Disclaimer: I was not the artist for this excellent ASCII drawing. This was found in an ASCII art archive along with several other scientific drawings.

A shape represented in mathematics as a "cardioid". It is expressed as this polar equation:
r = 2a(1 + cos(θ))

In Boxing, "heart" is used to describe the ability of a Boxer to overcome great adversity. To a large degree, heart is the most compelling aspect of the sport. A Boxing match is able to transcend many other sporting events when one (or both) of the fighters is pushed to their limits and continues to fight on. Heart is what makes a Boxer pick himself up after a devastating punch, continue fighting when they are being beaten and throw punches even when they keep getting hit by counters.

There are many great examples of fights that display heart. An excellent one is the recent match between Micky Ward and Arturo Gatti. In fact, the 9th round of that fight is probably best 3-minute display of heart you can find. Both fighters were completely exhausted going into the round. Early on Micky Ward landed his patented left hook to the body sending Gatti to the floor. A body blow like that is extremely painful and the pain lingers for a long time. Gatti managed to get to his feet. Ward then threw everything he could at Gatti. Gatti absorbed tremendous damage but refused to go down again. If this wasn't enough Gatti then showed tremendous heart and actually came back to win the middle of the round against the completely exhausted Ward. With still a minute left Micky Ward, well known as a "true warrior", again changed the direction of the round beating Arturo Gatti into the corner. This has to be one of the most amazing displays of skill and will power that I've ever witnessed in sports.

Heart is a very important factor in any fighter. Some fighters, like Micky Ward, have many fights where it was a major factor. Others, like Roy Jones, Jr., dominate their opponents so greatly that it never becomes a factor. Boxing fans always want to see their fighters get into tougher and tougher competitions. Many feel that you really can't judge a fighter completely until his heart has been tested. How will Roy Jones react when he finally gets knocked to the ground? That was certainly a question on people's minds about Mike Tyson when he fought Buster Douglas (of course, no one thought that Douglas would be Tyson's test).

There is a dark side to the concept of heart. A fighter with great heart will continue to fight on even when it is hopeless and they are getting injured. A perfect example of this is Evander Holyfield. He continues to fight even though it is dangerous at his age. If Holyfield were to fight someone like Lennox Lewis there is a good chance he would be dominated. Because of his great heart the fight would not end in a 6-round knockout. It would probably go the distance with Holyfield absorbing a great deal of damage. A fight like that would guarantee Holyfield being this generation's Mohammad Ali.

Heart is very often the most compelling aspect of Boxing. Even though the "fight choreography" in Rocky is ridiculous it is still a great Boxing movie. Rocky capture's the very important concept of heart by Balboa's drive and refusal to quit in his brutal match. Even though he loses the fight, the audience is moved by Rocky's tremendous heart. Fights that display this are rare and happen somewhat randomly. But when you can manage to witness a great display of heart you will rembember it forever.

The heart beats when the cardiac muscles around the outside of the organ contract. The heart contracts in two phases, first squeasing the blood that is in the two atria into the ventricles, and then squeasing the blood from the ventricles out of the heart, either to the lungs or to the rest of the body. When the cardiac muscles are contracting the heart is described as being in systole, and when it is relaxed it is described as being at diastole.

The heart muscle is made up of many cells, bound to each other my "intercolated discs". These intercolated discs spread electrical signals over the whole muscle very quickly, so when a message is sent to the muscle, it all acts as once, which is very important when trying to move large volumes of blood around. When the atria contract, the "sino-atrial node" sends a signal out, which spreads across all of the muscle. This signal is stopped by a non-conductive layer between the muscle surrounding the atria and the muscle surrounding the ventricles, so the whole of the heart doesn't contract at once. The atrial muscles contract, squeasing blood into the ventricles of the heart.

The signal from the sino-atrial node activates another node, the "atrioventricular node". Once the atrial muscles have contracted, the atrioventricular node sends another electrical signal down the "bundle of Hes", a clump of nerve cells bridging the non-conductive material between the atrial and the ventricular muscles. The signal travels down this, which half way down splits into two. At the bottom, or "apex" of the heart, the electrical signal is released from the nerve cells out into the muscles, and then spreads throughout the ventricular muscles making the ventricles contract.

The reason for the electrical signal travelling to the bottom of the heart before the ventricular muscles contract is two fold:
  • To provide a short delay between atrial and ventricular contractions
  • To make the ventricles contract from the bottom upwards if there is any delay at all in the signal spreading, ensuring that all the blood is squeased out of the heart

Systole lasts around 0.6 seconds when at rest (this will be shorter when the heart is beating fast). The heart then goes through diastole, a period of resting, which lasts around 0.3 seconds when at rest. During this time all the changes which have occured during systole are reset, and the heart prepares to contract again. Although the two sides of the heart pump to different places in the body (the right side pumps blood to the lungs for oxygenation, and the left side pumps oxygenated blood to the rest of the body), both sides contract at the same time as it is simply easier to make all the muscle contract at once.

All this makes the cardiac muscles surrounding the heart very active, so they use up a lot of oxygen and glucose respiring in order to keep up enough energy. As a result, 5% of the oxygenated blood pumped out by the heart is fed straight back in to the heart muscles to power them.

An interesting note is that the heart muscles are "Myogenic". This means that even when taken out of the body, the signals will still be send by the sino-atrial node for the heart to beat, and, as long as it has sufficient levels of glucose and oxygen, the heart will continue to beat. This is what makes heart transplants possible, as by cooling them the usage of oxygen and glucose can be kept to a minimum, and so the heart can be kept beating for up to a day (although it is usually no longer than 4 hours).

All journeys must have a some start,
today it's blood entering your heart:
      Two pipes join at the top
      of your blood's first pit-stop;
your atrium is where it'll fast dart.

So through the tricuspid valve blood seeps,
and then to a ventricle it ekes.
      That cavity then squeezes,
      with the force of ten sneezes
like a wound balista releases!

Past the big pulmonic valve blood’s bumped,
and into another tube it’s dumped.
      The blood goes in a lung,
      and with air it is wrung,
and back to the heart it is pumped.

Thus, into the atrium blood flows;
But alas, the cavum shall then close
      and the blood can't quite fit.
      It's let out through a slit--
pushed through the mitral valve blood goes!

Then into a ventricle goes the stuff,
but out again it is in a huff!
      Sans reason and order
      it goes to the aorta
which makes sure your organs get enough!

An Exquisite Organ


The organs make such fine delicacies

Take my heart for example.

It's a strong ventricled pumping machine

Steeped in iron rich blood and nutrients,

Webbed with intricate veins and arteries.

Why--any brutal carnivore would relish cooking up this rare find

Life has seasoned it for a sadist's palate:

A teaspoon of self-loathing to give it a bitter flavor,

A pinch of shame to make it sour,

Sprinkled with some lingering self doubt and questioning,

Infused with a good dose of ridicule and piercing laughter to balance out the flavors.

And cook it up with the ache for affection and understanding.

Why, Herr Chef, you have yourself a fine dish to serve

Perhaps it's best to serve it to your guests--cold.

Heart (?), n. [OE. harte, herte, heorte, AS. heorte; akin to OS. herta, OFies. hirte, D. hart, OHG. herza, G. herz, Icel. hjarta, Sw. hjerta, Goth. ha�xa1;rt, Lith. szirdis, Russ. serdtse, Ir. cridhe, L. cor, Gr. , . Cf. Accord, Discord, Cordial, 4th Core, Courage.]

1. Anat.

A hollow, muscular organ, which, by contracting rhythmically, keeps up the circulation of the blood.

Why does my blood thus muster to my heart! Shak.

In adult mammals and birds, the heart is four-chambered, the right auricle and ventricle being completely separated from the left auricle and ventricle; and the blood flows from the systematic veins to the right auricle, thence to the right ventricle, from which it is forced to the lungs, then returned to the left auricle, thence passes to the left ventricle, from which it is driven into the systematic arteries. See Illust. under Aorta. In fishes there are but one auricle and one ventricle, the blood being pumped from the ventricle through the gills to the system, and thence returned to the auricle. In most amphibians and reptiles, the separation of the auricles is partial or complete, and in reptiles the ventricles also are separated more or less completely. The so-called lymph hearts, found in many amphibians, reptiles, and birds, are contractile sacs, which pump the lymph into the veins.


The seat of the affections or sensibilities, collectively or separately, as love, hate, joy, grief, courage, and the like; rarely, the seat of the understanding or will; -- usually in a good sense, when no epithet is expressed; the better or lovelier part of our nature; the spring of all our actions and purposes; the seat of moral life and character; the moral affections and character itself; the individual disposition and character; as, a good, tender, loving, bad, hard, or selfish heart.

Hearts are dust, hearts' loves remain. Emerson.


The nearest the middle or center; the part most hidden and within; the inmost or most essential part of any body or system; the source of life and motion in any organization; the chief or vital portion; the center of activity, or of energetic or efficient action; as, the heart of a country, of a tree, etc.

Exploits done in the heart of France. Shak.

Peace subsisting at the heart Of endless agitation. Wordsworth.


Courage; courageous purpose; spirit.

Eve, recovering heart, replied. Milton.

The expelled nations take heart, and when they fly from one country invade another. Sir W. Temple.


Vigorous and efficient activity; power of fertile production; condition of the soil, whether good or bad.

That the spent earth may gather heart again. Dryden.


That which resembles a heart in shape; especially, a roundish or oval figure or object having an obtuse point at one end, and at the other a corresponding indentation, -- used as a symbol or representative of the heart.


One of a series of playing cards, distinguished by the figure or figures of a heart; as, hearts are trumps.


Vital part; secret meaning; real intention.

And then show you the heart of my message. Shak.


A term of affectionate or kindly and familiar address.

"I speak to thee, my heart."


Heart is used in many compounds, the most of which need no special explanation; as, heart-appalling, heart-breaking, heart-cheering, heart-chilled, heart-expanding, heart-free, heart-hardened, heart-heavy, heart-purifying, heart-searching, heart-sickening, heart-sinking, heart-stirring, heart-touching, heart-wearing, heart-whole, heart-wounding, heart-wringing, etc.

After one's own heart, conforming with one's inmost approval and desire; as, a friend after my own heart.

The Lord hath sought him a man after his own heart. 1 Sam. xiii. 14.

-- At heart, in the inmost character or disposition; at bottom; really; as, he is at heart a good man. -- By heart, in the closest or most thorough manner; as, to know or learn by heart. "Composing songs, for fools to get by heart" (that is, to commit to memory, or to learn thoroughly). Pope. -- For my heart, for my life; if my life were at stake. [Obs.] "I could not get him for my heart to do it." Shak. -- Heart bond Masonry, a bond in which no header stone stretches across the wall, but two headers meet in the middle, and their joint is covered by another stone laid header fashion. Knight. -- Heart and hand, with enthusiastic cooperation. -- Heart hardness, hardness of heart; callousness of feeling; moral insensibility. Shak. -- Heart heaviness, depression of spirits. Shak. -- Heart point Her., the fess point. See Escutcheon. -- Heart rising, a rising of the heart, as in opposition. -- Heart shell Zool., any marine, bivalve shell of the genus Cardium and allied genera, having a heart-shaped shell; esp., the European Isocardia cor; -- called also heart cockle. -- Heart sickness, extreme depression of spirits. -- Heart and soul, with the utmost earnestness. -- Heart urchin Zool., any heartshaped, spatangoid sea urchin. See Spatangoid. -- Heart wheel, a form of cam, shaped like a heart. See Cam. -- In good heart, in good courage; in good hope. -- Out of heart, discouraged. -- Poor heart, an exclamation of pity. -- To break the heart of. (a) To bring to despair or hopeless grief; to cause to be utterly cast down by sorrow. (b) To bring almost to completion; to finish very nearly; -- said of anything undertaken; as, he has broken the heart of the task. -- To find in the heart, to be willing or disposed. "I could find in my heart to ask your pardon." Sir P. Sidney. -- To have at heart, to desire (anything) earnestly. -- To have in the heart, to purpose; to design or intend to do. -- To have the heart in the mouth, to be much frightened. -- To lose heart, to become discouraged. -- To lose one's heart, to fall in love. -- To set the heart at rest, to put one's self at ease. -- To set the heart upon, to fix the desires on; to long for earnestly; to be very fond of. -- To take heart of grace, to take courage. -- To take to heart, to grieve over. -- To wear one's heart upon one's sleeve, to expose one's feelings or intentions; to be frank or impulsive. -- With all one's whole heart, very earnestly; fully; completely; devotedly.


© Webster 1913.

Heart (?), v. t.

To give heart to; to hearten; to encourage; to inspirit.


My cause is hearted; thine hath no less reason. Shak.


© Webster 1913.

Heart, v. i.

To form a compact center or heart; as, a hearting cabbage.


© Webster 1913.

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