Skip to main content
Select Source:

heart

heart Throughout human history the rhythmic beat of the heart has quintessentially represented life. Until the advent of the heart–lung machine, the lack of a heart beat, unless reversed within a few minutes, invariably signalled death. The beat of our own heart can be apparent to us in the pulse felt, or seen, at various parts of the body, occasionally heard or — because of an unusual rhythm or ‘skipped’ beat — noticeable in the chest.

The heart is a hollow muscular organ. It acts as the ‘prime mover’ for the circulation of the blood and the maintenance of the blood pressure. A certain volume of blood is delivered with each beat, and a further key aspect is the pressure at which this flow is delivered. Vital functions such as those of lungs and kidneys, or the exchange of components of the blood and tissue fluid at the capillaries, are critically dependent on the pressure achieved within the circulatory system.

Anatomy

The heart comprises a series of blood-filled chambers; the walls are composed virtually entirely of muscle cells of a type unique to the heart (cardiac myocytes). The heart is actually two double pumps acting in series; there are four chambers in all. The right side receives blood returning from the entire body (in the great veins) and pumps it into the pulmonary artery, which supplies only the alveoli (gas exchange sites) in the lungs. The left side receives blood from the lungs and pumps it into the aorta, the largest artery. (The heart is generally illustrated as seen from the front, so ‘left’ and ‘right’ appear mirrored.) The aorta branches to form the arterial tree that supplies blood to the whole body. The heart, appropriately, is itself the first organ supplied with blood from the aorta. The coronary arteries open from the beginning of the aorta and take blood to all parts of the heart tissue. Each side of the heart has an upper chamber, the atrium (plural: ‘atria’), into which the veins drain. They serve as antechambers to the respective ventricles, the thicker-walled chambers that lie below them.

Atria and valves

The arrangement of one-way valves and the prevailing pressures mainly determine blood flow from vein–to–atrium–to– ventricle during the cyclic activity of the heart beat, but some pumping of blood by the atria into the ventricles also occurs. The valves preventing back-flow from ventricle to atrium are tough, parachute-like structures partly anchored in the connective tissue plate which forms the physical union of the ventricular and atrial portions of the heart. Their free edges are restrained by several papillary muscles. These are slim extensions from the inner wall of the ventricles, each with a tendinous end fused with the valve; acting like parachute cords, they prevent the valve being pushed through into the atrium as its flaps become filled when the ventricle contracts and puts pressure on its contents. The mitral (or bicuspid) valve on the left side has two flaps, and the tricuspid valve on the right has three. The ‘parachutes’ press together forming a complete closure preventing regress of blood into the respective atrium whence it came. Instead, when the pressure has risen sufficiently, blood is directed into the pulmonary artery and the aorta through one-way valves which separate them from, and prevent back-flow into, their respective ventricles (see Figure).

The heart beat

The heart beats between 60 and 220 times per minute in a typical young adult; 40 to 50 million beats per year. The rate alters, often rather obviously, according to one's state of physical and mental activity. This results in pumping over 3 million litres of blood (per year) through the body and an equal volume through the lungs. The pump work done by the heart is equivalent to lifting a 1 kg weight to about twice the height of Mount Everest each day. This level of persistent, rhythmic, and decidedly dynamic activity may provoke a sense of awe, although it is hardly more remarkable than the prosaic activity of every other organ — except in its absolute necessity to keep at it! We will first consider the electrical processes of the heart since, like many muscles, it is triggered into activity (contraction, the heart beat) by an electrical wave. This section is followed by consideration of contraction itself.

Electrical aspects

The left and right atria beat virtually simultaneously and then, after a fraction of a second's delay, both ventricles contract. Electrical activity, as in most other muscles, triggers the contraction. This activity arises not from excitatory nerve fibres, but spontaneously within the heart itself from a small clump of pacemaker cells near the point where the vena cava joins the right atrium: the sino-atrial (SA) node. The electrical wave, or action potential, spreads across the heart from cell to cell. This spread is made possible because each heart cell is connected to its immediate neighbours at several contact regions which offer a relatively low resistance to the flow of electrical current. All the muscle cells of the heart are thus electrically linked together. This means that the activity spreads as a wave, its direction determined by the cell-to-cell couplings available. It also means that, as far as we know, every cardiac myocyte is active at some stage during every heart beat. The muscle cells of the atria and ventricles only make electrical contact in one small region, the atrio-ventricular (AV) node at the centre of the heart. Thus, activity follows a predictable, regular path — across the right and left atria, through the AV node, along specialized faster-conducting heart cells (Purkinje fibres) on the internal face of the muscular wall between the two ventricles (interventricular septum), and thence through the substance of both ventricles. Heart cells, like other electrically excitable cells, become inexcitable (refractory) for a brief period after each action potential. Consequently, once the wave has passed right through the ventricles it ceases, since there are no non-refractory cells available to excite. A new wave is spontaneously initiated at the pacemaker region.

Contractile (mechanical) aspects

All the heart muscle cells are thus electrically excited and it is this that triggers them to contract. The wave of contraction, therefore, follows the same sequence: atria first, then ventricles. The electrical activity triggers an abrupt rise in the concentration of ‘free’ calcium ions inside the cells — a common feature in signalling contraction in muscle of every type. The calcium ions required are derived in part by influx from the extracellular fluid, in part by release from intracellular stores in the sarcoplasmic reticulum. The influx is through calcium-selective channels in the surface membrane which are opened by the depolarization. The influx itself transiently promotes further influx, and also triggers the release of more calcium from the intracellular store.

In each ventricle, as the muscular walls contract (develop tension and shorten) they press upon the blood they enclose. The pressure rises and the AV valve fills out and closes. At this stage of the cycle, the exit valve into the relevant artery (pulmonary artery or aorta) is also closed because the pressure in the arteries is higher than that in the ventricles. Temporarily, each ventricle is thus a closed chamber, it can neither lose nor gain blood, so pressure rises quickly until it exceeds that in the exit artery; the exit valve is then pushed open and blood is ejected, squirted from the ventricles as their muscular walls continue to shorten. The pressure at which the valve opens is much higher on the left side than on the right side, in accordance with the higher blood pressure in the aorta and its branches than in the pulmonary artery and its branches. The resistance offered by the lungs to blood flow is much less than that by the body generally; thus the pressures required of the right ventricle can be lower, yet achieve the same flow rate. Both ventricles eject the same volume of blood (the stroke volume): in the adult heart, about 70 ml (half a teacup) which is half or less of the volume it contained. As action potential finishes, the intracellular calcium concentration has already started to reduce again: some calcium is being ‘pumped’ back into the store, and some is leaving the cell by an ion exchange process. With the raised calcium concentration signal thereby removed, the force of contraction quickly wanes in the muscle, so ventricular pressure falls. The elasticity of the arteries, which were dilated when blood was ejected into them, now ensures that a higher pressure is sustained in them than in the rapidly relaxing ventricles (the ‘garden hose’ effect, familiar to those who have turned off a hose-pipe supply tap only to see water continue squirting as the elastic pipe collapses). The respective exit valves are thus pushed closed again, preventing reflux into the ventricles. Blood pressure, therefore, falls more slowly in the arteries than in the ventricles. At this stage about 90 ml of blood remains in each ventricle. Pressure continues to fall quickly until it is below that in the atria. Thus, the AV valves are pushed open, allowing blood to flow from the atria into the ventricles ‘topping them up’ with more blood. (Despite the appearance in some published schematic diagrams and ‘cartoon’ sequences, at all stages of the heart beat the chambers are ‘full’ of blood. It is the enclosed volume which changes, depending on the tension and elasticity of the muscular walls and the status of the inlet and outlet valves.)

The return of the ventricle to its ‘resting’ shape between beats is due to its own elasticity. Like a squeezed sponge or hollow rubber ball, this significantly ‘sucks’ blood from the atria, thereby contributing to its own filling. The reduction of this factor in old age or its enhancement by athletic training have a major effect on overall cardiac function. These effects are analogous to problems associated with ‘stiff’ inelastic valves which perhaps more obviously compromise effective flow in and out of the chambers of the heart.

The state when the heart is contracting is termed systole (sis'-toe-lee); the relaxed state is termed diastole (di-a'-stoe-lee).

Control of pump function

The cardiac output is the volume of blood pumped per minute by each ventricle — some 5 litres/minute at ‘rest’ — and is simply the product of heart rate and stroke volume. Cardiac output will thus alter if either varies. The stroke volume is in turn influenced by cardiac filling and by the contractility of the cardiac muscle itself — its intrinsic ability to contract (shorten and/or produce tension).

Heart rate

The earliest human hunters will have noticed, like later horror film makers, that even when removed from the body, the heart continues to beat for a time. Other organs also continue to live, but their activity is hardly as impressive as that of the heart.

Because all the cells of the heart are electrically connected to their neighbours, the whole behaves as a unit. Most regions are inactive, unless artificially stimulated. The activity of the regions with the property of ‘firing’ spontaneously is conducted to all their inactive neighbours, so they act as pacemakers. The inherent pacemaker firing rate, typically about 100 per minute, is influenced by nerve actions of the autonomic nervous system: sympathetic nerves release noradrenaline which increases rate, and parasympathetic (vagus) nerve fibres release acetylcholine which slows the rate. Heart rate typically varies between 60 per minute (in deep sleep) to approaching 200 per minute (during brief bursts of maximal exercise). The normal ‘resting’ rate while sitting, relaxed, is about 70 per minute, but shows wide variation amongst entirely healthy individuals. (In one university class of 350 twenty-year-old students, the range was 48 to 90 per minute.) One common feature is a marked variation within the breathing cycle: breathing in usually increases the rate. Physical fitness, particularly that associated with endurance rather than muscle strength, is often associated with a low resting rate. Extremes such as the tennis player Bjorn Borg, or the professional cyclist Miguel Indurain, with resting values in the low 30s per minute, are well known. Young children have higher resting rates; whilst still in the womb, a baby will have a rate of 120 to 160 beats per minute; it is often reported that rates above 140 indicates a female baby, but there are more reliable tests!

Cardiac filling

‘Filling’ reflects the flow of blood back into the heart (venous return from the lungs and the body). William Harvey observed that the presence of valves requires that blood in the larger veins can only flow towards the heart, the key to recognizing that blood circulates. Amongst other factors, the extent of muscular activity, breathing movements, and body positions (standing, lying, arms or legs raised) all affect the rate of return of blood to the heart. Cardiac muscle shows the unusual property that, within limits, it contracts more powerfully when starting from stretched lengths, so that the ventricle ‘empties’ more forcibly when it is ‘filled’ more than usual. This is achieved at trivial extra metabolic cost; the efficiency of pumping thus increases as output increases; surely a paradigm for ‘productivity gains’. This property allows the heart to compensate automatically when the volume of blood within it at the start of the beat (the end diastolic volume) is greater than previously, by pumping more forcefully, thus ejecting a larger volume. This feature is termed Starling's ‘Law of the Heart’, after one of its discoverers.

Contractility

It is obvious that an intrinsically stronger heart will be able to eject blood more forcefully and more completely. Unlike our voluntary (skeletal) muscles, the ‘strength’ of heart muscle can vary quickly, even from one beat to the next. This is because it is sensitive to chemical influences (especially of adrenaline/noradrenaline) and electrical influences that can rapidly modify the intracellular processes that underlie contraction. Additionally, as with voluntary muscle, the extent of growth and development of the heart muscle will affect the overall strength of the organ; athletes generally have thicker heart walls which match the larger muscles in their thicker limbs. A normal, sudden increase in contractility is associated with the onset of physical activity or even with its anticipation; this is signalled to the heart, along with the increase in heart rate, by activity in the sympathetic nerve fibres which release noradrenaline. The combination of higher rate and stronger, more rapid contraction tends to match cardiac output to the increased ‘demands’ for blood flow to the exercising muscles.

The heart of the matter and the matter of the heart

The control systems which influence the heart rate and strength of beating are the same as those implicated in such apparently diverse processes as blushing, breathing rate, sexual arousal, mental stress, or alertness. These links seem to have been recognized by our forebears in advance of the definitive precision of the discoveries of cardiovascular physiology. Poets report that hearts leap, hearts are strong, hearts are united, hearts are hot, heart strings are plucked, hearts are ‘in the mouth’, hearts become feeble, hearts are chilled, hearts tremble, and hearts are broken. In human history, the nature of the circulation of the blood and the (quite literally) central role of the heart in this system are still recent discoveries, even though they rank with the very earliest of the truly ‘modern’ scientific method. Nevertheless, the heart (with perhaps the eye) is the organ most quoted in literature and song to define the essential qualities of life and even its very presence. The ready perception of the action of the heart, its racing rate when we are excited or surprised, aroused or shocked, the shallow, rapid beat encountered in feverish poor health, the occasional irregularity of beat that can concern us all (often, thankfully, quite unnecessarily), together form the shared ‘heart’ experiences of mankind that writers and poets have ever drawn upon. We are generally blissfully unaware of the other hives of metabolic industry that contribute to our physiology. The liver, the thyroid, the hypothalamus, the pituitary, the spleen, the pancreas, not one of these is dignified with a property recognizable to their owners. It is surely the literal vitality of the heart's rhythmic beating, the recognition of its link to the movements of blood, the necessary identity between this continual activity and life itself (outside an operating theatre) that validates the continuing truth of poetic notions of ‘heart’

David J. Miller


See cardiovascular system.See also autonomic nervous system; blood pressure; blood circulation; blood vessels; cardiac muscle; heart attack; heart block; heart failure; heart sound.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." The Oxford Companion to the Body. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." The Oxford Companion to the Body. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/heart

"heart." The Oxford Companion to the Body. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/heart

Heart

Heart

In humans, the heart is a pulsating organ that pumps blood throughout the body. On average, the heart weighs about 10.5 ounces (300 grams). It is a four-chambered, cone-shaped organ about the size of a closed fist. It lies under the sternum (breastbone), nestled between the lungs. The heart is covered by a triple-layered, fibrous sac called the pericardium. This important organ is protected within a bony cage formed by the ribs, sternum, and spine.

Words to Know

Angina pectoris: Chest pain that occurs when blood flow to the heart is reduced, resulting in a shortage of oxygen.

Aorta: Largest blood vessel in the body.

Atherosclerosis: Condition in which fatty material such as cholesterol accumulates on an artery wall forming plaque that obstructs blood flow.

Atrioventricular node: Area of specialized tissue that lies near the bottom of the right atrium that fires an electrical impulse across the ventricles, causing them to contract.

Atria: Upper heart chambers that receive blood.

Diastole: Period of relaxation and expansion of the heart when its chambers fill with blood.

Mitral valve: Valve with two cusps that separates the left atrium from the left ventricle.

Pericardium: Fibrous sac that encloses the heart.

Sinoatrial node: Area of specialized tissue in the upper area of the right atrium that fires an electrical impulse across the atria, causing them to contract.

Systole: Rhythmic contraction of the heat.

Tricuspid valve: Fibrous, three-leaflet valve that separates the right atrium from the right ventricle.

Ventricles: Lower heart chambers that pump blood.

In its ceaseless work, the heart contracts more than 100,000 times a day to drive blood through about 60,000 miles (96,000 kilometers) of vessels to nourish each of the trillions of cells in the body. Each contraction of the heart forces about 2.5 ounces (74 milliliters) of blood into the bloodstream. This adds up to about 10 pints (4.7 liters) of blood every minute. An average heart will pump about 1,800 gallons (6,800 liters) of blood each day. With exercise, that amount may increase as much as six times. In an average lifetime, the heart will pump about 100 million gallons (380 million liters) of blood.

The heart is divided into four chambers. The upper chambers are the atria (singular atrium). The lower chambers are the ventricles. The wall that divides the right and left sides of the heart is the septum. The atria are thin-walled holding chambers for blood that returns to the heart from the body. The ventricles are muscular chambers that contract rhythmically to propel blood through the body.

Movement of blood between chambers and in and out of the heart is controlled by valves that allow movement in only one direction. Between the atria and ventricles are atrioventricular (AV) valves. Between the ventricles and the major arteries into which they pump blood are semilunar (SL) valves. The "lub-dup" sounds that a physician hears through a stethoscope occur when the heart valves close. The AV valves produce the "lub" sound upon closing, while the SL valves cause the "dup" sound.

Movement of blood through the heart

Blood carrying no oxygen (oxygen-depleted) returns to the right atrium of the heart through the vena cava, a major vein. It then passes through the tricuspid or right AV valve into the right ventricle. The tricuspid valve is so named because it has three cusps or flaps that open and close to control the flow of blood. When the right ventricle contracts, blood is forced from the heart into the pulmonary artery through the pulmonary SL valve.

The pulmonary artery is the only artery in the body that carries oxygen-depleted blood. It carries this blood into the lungs, where the blood releases carbon dioxide and other impurities and picks up oxygen. The freshly oxygenated blood then returns to the left atrium through the four pulmonary veins. The blood then passes through the mitral or left AV valve into the left ventricle.

The left ventricle has the hardest task of any chamber in the heart. It must force blood from the heart into the body and head. For that purpose it has a much thicker wall, approximately three times thicker than the wall of the right ventricle. When the left ventricle contracts, blood passes through the aortic SL valve into the largest artery in the bodythe aortato be carried and distributed to every area of the body.

The heart muscle or myocardium is unique in that it is not under voluntary control (a person cannot cause it to start and stop at will) and it must work without ceasing for a lifetime. The myocardium requires a great deal of nourishment, and the arteries that feed it are the first to branch off from the aorta. These coronary arteries pass down and over the heart, providing it with an abundant and uninterrupted blood supply.

The heart cycle and nerve impulses

Each heartbeat or heart cycle (also known as the cardiac cycle) is divided into two phases. The two atria contract while the two ventricles relax. Then, the two ventricles contract while the two atria relax. The contraction phase is known as systole, while the relaxation phase is known as diastole. The heart cycle consists of a systole and diastole of both the atria and ventricles. At the end of a heartbeat all four chambers rest.

The pattern of heart chambers filling and emptying in sequence is controlled by a system of nerve fibers. They provide the electrical stimulus to trigger contraction of the heart muscle. The initial stimulant is provided by a small strip of specialized tissue in the upper area of the right atrium. This is called the sinoatrial or SA node. The SA node fires an electrical impulse that spreads across the atria, causing them to contract. The impulse also reaches another node, the atrioventricular or AV node. (The AV node lies near the bottom of the right atrium just above the ventricle.) After receiving the SA impulse, the AV node sends out its own electrical impulse. The AV impulse travels down a specialized train of fibers into the ventricular muscle, causing the ventricles to contract. In this way, the contraction of the atria occur slightly before the contraction of the ventricles.

The electrical activity of the heart can be measured by a device called the electrocardiograph (EKG). Variations in the heart's electrical system can lead to serious, even dangerous, consequences. When that occurs, an electrical stimulator called an artificial pacemaker must be implanted to take over the regulation of the heartbeat. The small pacemaker can be implanted under the skin near the shoulder. Long wires from the pacemaker are fed into the heart and implanted in the heart muscle. The pacemaker can be regulated for the number of heartbeats it will stimulate per minute. Newer pacemakers can detect the need for increased heart rate when the individual is exercising or under stress.

Heart diseases

Heart disease is the number-one cause of death among people living in the industrial world. Preventive measures, such as an improved diet and regular exercise, are the best methods to overcome heart disease.

Congenital heart disease is any defect in the heart present at birth. About 1 out of every 100 infants are born with some sort of heart abnormality. Many of these congenital defects do not need to be treated. The most common type of congenital heart disease is the atrial septal defect. In this condition, an opening in the septum between the right and left atria allows blood from the two chambers to mix. If the hole is small, it does not cause a problem. But a larger opening that allows too much blood to mix can cause the right ventricle to be overwhelmed with blood,

a condition that eventually leads to heart failure. The defect can be corrected through a surgical procedure in which a patch is placed over the opening to seal it.

Coronary heart disease (also known as coronary artery disease) is the most common form of heart disease. A condition known as atherosclerosis results when fatty material such as cholesterol accumulates on an artery wall forming plaque that obstructs blood flow. When the obstruction occurs in one of the main arteries leading to the heart, the heart

does not receive enough blood and oxygen and its muscle cells begin to die. The primary symptom of this condition is pain in the upper left part of the chest that radiates down the left armwhat is called angina pectoris. A heart attack (myocardial infarction) occurs when blood flow to the heart is completely blocked.

Numerous types of drugs have been developed to treat patients with heart disease. Some drugs are given to make the heart beat more slowly, removing stress placed on it. Other drugs cause blood vessels to dilate or stretch. This also reduces stress on the heart. A third important type of drug reduces cholesterol in the blood.

Surgical procedures are often used to treat heart disease. One procedure is known as coronary bypass surgery. To supply blood to the coronary artery beyond the point of blockage, blood vessels are taken from other parts of the body (often the leg) and connected to the artery. Another commonly performed procedure is angioplasty, during which narrowed arteries are stretched to enable blood to flow more easily. The surgery involves threading a balloon catheter (tube) through the coronary artery and then stretching the artery by inflating the balloon.

The most dramatic treatment for heart disease is the replacement of damaged hearts with healthy human or even animal hearts. The first successful human heart transplant was performed by South African surgeon Christiaan Barnard (1922 ) in 1967. The patient, however, died in 18 days. Many patients who received early heart transplants died days or months after the operation, mostly because their bodies rejected the new organ. In the early 1980s, effective drugs were developed to fight organ rejection. By the late-1990s, the one-year survival rate of patients receiving heart transplants was over 81 percent. For those who survived the first year, survival rates rose to over 90 percent.

[See also Circulatory system; Electrocardiogram; Transplant, surgical ]

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Heart." UXL Encyclopedia of Science. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"Heart." UXL Encyclopedia of Science. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/heart-2

"Heart." UXL Encyclopedia of Science. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/heart-2

Heart

Heart

Rock group

For the Record

Selected discography

Sources

Heart is one of the few rock groups to feature womenSeattle-born sisters Ann and Nancy Wilsonas lead performers. The band has been working together, with some personnel changes, since the early 1970s, when the members were living in western Canada. Since their first album, Dreamboat Annie, went platinum in 1975, the entertainers in Heart have known every extreme that plagues famous rock bands, from the most dizzying heights of success to the most frustrating lulls in appeal.

As Gwenda Blair noted in Ms.magazine, however, the Wilson sisters have always managed to hold up, whether they were facing breakneck superstar tours, or the seemingly endless uphill struggle to break out of obscurity. Blair attributed the groups tenacity to the Wilsons special bond, the easy camaraderie of best girlfriends mixed with the special familiarity and sensitivity of sisterhood. The reporter added: The continuity and companionship provided by that combination have carried the Wilsons a great distance over the years.

For the Record

Group formed in Seattle, Wash., in 1970; originally billed as White Heart; also performed briefly as Hocus-Pocus before adopting name Heart, 1970. Original band members iuncluded Anne Wilson (vocals), Nancy Wilson (guitar), Roger Fisher (guitar), Howard Leese (guitar), Michael Derosier (drums), and Steve Fossen (bass); have subsequently included more than twenty other members.

Addresses: Office Suite 333, 219 First Ave. North, Seattle WA 98109.

Indeed, Heart has enjoyed an impressive level of success throughout most of its two-decade-long existence: four platinum albums, scores of sold-out tours, and number-one hits in the 1970s and 1980s. Blair described the groups draw on its listeners: Hearts music, with its bouncing-up-and-down-in-your-seat sound is what millions of people like. To some critics Hearts sound may be sheer bubblegum blare fit only for undiscerning and voracious teen appetites. But to Ann and Nancy, escape and fantasy, not heavy messages or avant-garde music, is what rock is all about.

Press coverage of Heart has centered on the Wilson sisters almost since the band began playing together in a one-room house in Vancouver. By all accounts, including their own, Ann and Nancy were ordinary, middle-class young women who grew up in Bellevue, a suburb of Seattle, Washington. They were teens in the 1960s, daughters of parents who embraced the radical causes and experimental lifestyles of that era. We were pretty normal for the time we grew up in, Ann told Rolling Stone.What we experienced was going on in suburbs all over the country. We werent that different. On the other hand, high school chum Sue Ennis, who has since written songs for Heart, recalled that the Wilsons were aloof from most of their peers, disdainful of the standard high school popularity contests, and happiest when they were alone in a bedroom, composing or listening to rock music. To quote Rolling Stone contributor Daisann McLane, as teenagers Ann and Nancy played and wrote songs constantly, moody evocations of late-adolescent alienation.

Ann graduated from Sammamish High School in 1968 with one ambition: to sing in a band. She began working with Tex Blaine and the Skyway Ranch Boys, but soon joined a psychedelic rock band called White Heart, staffed by guitarist Roger Fisher and bassist Steve Fossen. After doing a few gigs under the name Hocus-Pocus, the group members opted to call themselves Heart. Ann began a long romantic relationship with Michael Fisher, Rogers brother, and Nancy eventually became involved with both the band (as a guitarist and flute player) and with Roger Fisher. Blair wrote of the Wilsons: Two real-life Barbies, they acquired their very own Kenstwo handsome brothers who were also members of Heart.

Hearts early existence can hardly be described as a Barbie-and-Ken dream life. The band members moved to Vancouver and subsisted on brown rice and stolen fruit while trying to build a following. Laura Fissinger describes the groups struggle, and ultimate success, in Rolling Stone: In the early Seventies, Heart was just one more club band, doing six nights a week, four sets a night, and letter-perfect carbons of Stairway to Heaven. Guitarist Howard Leesethe only other Heart member still around from the early dayswas working for Mushroom records in Vancouver when he was tapped to produce the groups first demo. Leeses employers initially courted Ann as a solo act. When she said no, they took the whole passel.

That whole passel turned out a debut album, Dreamboat Annie, that went platinum in seven months despite its obscure Canadian label and minimal promotion budget. The best known song from the album, a mysterious rocker called Magic Man, is today considered a classic. Heart turned out several more hit albumsLittle Queen (1977), Magazine (1978), Dog and Butterfly (1978), and Bebe Le Strange (1980)and had smash singles with Crazy on You, Barracuda, and Dog and Butterfly. McLane noted that the most successful Heart songs graft heavy-metal musicianship to emotional, image-laden lyrics. This unlikely combination is held together by Anns powerful, three-octave soprano. She can belt and screech the hardest rock tune, then slide through every delicate nuance of a tender folk ballad.

Nonstop touring also helped to promote Heart as a top rock band. The groups dynamicstwo sisters romantically involved with two brothersmade for frenzied press coverage and, at first, energetic live shows. Then problems began to beset Heart. First the group broke its contract with Mushroom and underwent a costly court battle over some unfinished tapes the label wanted to release. Then Ann ended her involvement with Mike Fisher, even though she credited him with the bands success and suffered pangs of anxiety without his support. Nancy followed suit by breaking up with Roger Fisher and then firing him from the band. For a variety of reasonsthe loss of Rogers riveting concert presence among themHeart went into a nosedive in the early 1980s.

The group continued to tour relentlessly, and continued to produce albums, but popular support faded. Our management had us on the road nonstop, Nancy told Rolling Stone.We surfaced from our exhaustion just long enough to see that we were being mishandled and swept under the carpet. Having taken responsibility for the direction of the band, the Wilsons switched from Epic to Capitol records in 1984. The following yearand on into 1986Heart experienced a major comeback with their ninth album, Heart, and two top-selling singles, What About Love and These Dreams.

Ann and Nancy, whose titillating music videos have occasionally angered censorious critics, admit that their music is wrong for any given time for what was inan observation echoed by some rock writers. The media may be condescending toward Hearts basic blueprint of heavy metal meets Joni Mitchell, to quote Fissinger, but audiences respond to it warmly. According to Ariel Swartley in Rolling Stone, the members of Heart need no showmanship to carry them: conviction has already been built into the melody, tension embedded in the harmonies. Swartley also concluded that in Ann Wilson, Heart has possibly the greatest female rock & roll singer ever. And when shes hot the only reserved youre thinking about is your seat for the next show.

Selected discography

Dream boat Annie, Mushroom, 1976.

Little Queen, Portrait, 1977.

Magazine, Mushroom, 1978.

Dog and Butterfly, Portrait, 1978.

Bebe Le Strange, Epic, 1980.

Greatest Hits Live, Epic, 1980.

Private Audition, Epic, 1982.

Passionworks, Epic, 1983.

Heart, Capitol, 1985.

Bad Animals, Capitol, 1987.

Sources

High Fidelity, February, 1978.

Mademoiselle, June, 1982.

Rolling Stone, November 30, 1978; March 22, 1979; April 24, 1986.

Anne Janette Johnson

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Heart." Contemporary Musicians. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"Heart." Contemporary Musicians. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/education/news-wires-white-papers-and-books/heart

"Heart." Contemporary Musicians. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/news-wires-white-papers-and-books/heart

heart

heart / härt/ • n. 1. a hollow muscular organ that pumps the blood through the circulatory system by rhythmic contraction and dilation. In vertebrates there may be up to four chambers (as in humans), with two atria and two ventricles. ∎  the region of the chest above the heart: holding hand on heart for the Pledge of Allegiance. ∎  the heart regarded as the center of a person's thoughts and emotions, esp. love or compassion: hardening his heart, he ignored her entreaties he poured out his heart to me | he has no heart. ∎  one's mood or feeling: they had a change of heart. ∎  courage or enthusiasm: they may lose heart as the work mounts up Mary took heart from the encouragement handed out I put my heart and soul into it and then got fired. 2. the central or innermost part of something: right in the heart of the city. ∎  the vital part or essence: the heart of the matter. ∎  the close compact head of a cabbage or lettuce. 3. a conventional representation of a heart with two equal curves meeting at a point at the bottom and a cusp at the top. ∎  (hearts) one of the four suits in a conventional pack of playing cards, denoted by a red figure of such a shape. ∎  a card of this suit. ∎  (hearts) a card game similar to whist, in which players attempt to avoid taking tricks containing a card of this suit. 4. the condition of agricultural land as regards fertility. PHRASES: after one's own heart of the type that one likes or understands best; sharing one's tastes: a man after God’s own heart. at heart in one's real nature, in contrast to how one may appear: he's a good guy at heart. break someone's heart overwhelm someone with sadness. by heart from memory. close (or dear) to (or near) one's heart of deep interest and concern to one. from the (bottom of one's) heart with sincere feeling: their warmth and hospitality is right from the heart. give (or lose) one's heart to fall in love with. have a heart [often in imper.] be merciful; show pity. have a heart of gold have a generous nature. have the heart to do something be insensitive or hard-hearted enough to do something: I don't have the heart to tell her. have (or put) one's heart in be (or become) keenly involved in or committed to (an enterprise). have one's heart in one's mouth be greatly alarmed or apprehensive. have one's heart in the right place be sincere or well intentioned. heart of stone a stern or cruel nature. hearts and flowers used in allusion to extreme sentimentality. hearts and minds used in reference to emotional and intellectual support or commitment: a campaign to win the hearts and minds of America's college students. one's heart's desire a person or thing that one greatly wishes for. one's heartstrings used in reference to one's deepest feelings of love or compassion: the kitten's pitiful little squeak tugged at her heartstrings. in one's heart of hearts in one's inmost feelings. take something to heart take criticism seriously and be affected or upset by it. wear one's heart on one's sleeve make one's feelings apparent. with all one's heart (or one's whole heart) sincerely; completely. with one's heart in one's boots in a state of great depression or trepidation: I had to follow her with my heart in my boots.DERIVATIVES: heart·ed adj. [in comb.] a generous-hearted woman. ORIGIN: Old English heorte, of Germanic origin; related to Dutch hart and German Herz, from an Indo-European root shared by Latin cor, cord- and Greek kēr, kardia.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart-1

"heart." The Oxford Pocket Dictionary of Current English. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart-1

Heart

199. Heart

See also 14. ANATOMY ; 51. BODY, HUMAN .

anginophobia
an abnormal fear of angina pectoris.
arrhythmia, arhythmia, arythmia, arrythmia
any abnormality in the rhythm of the heartbeat. arrhythmic, arhythmic, arythmic, arrythmic, adj.
cardialgia, cardialgy
a burning or other painful feeling in the stomach or esophagus; heartburn.
cardioangiology
Medicine. the specialty that treats the heart and the blood vessels.
cardiocentesis
Medicine. the surgical puncture or incision of the heart. Also called cardiopuncture.
cardiodynamics
the branch of medical science that studies the forces and motions involved in the hearts actions.
cardiodynia
Medicine. a pain in the heart.
cardiogenesis
Medical Science, the study of the development of the heart in the embryo.
cardiograph
an instrument to record the action of the heart. cardiographer, n. cardiographic, adj.
cardiography
Medicine. the technique of graphically recording some physical or functional features of heart action.
cardiokinetic
an agent that stimulates action of the heart.
cardiology
Medicine. the study of the heart and its functions. cardiologist, n. cardiologic, cardiological, adj.
cardiomalacia
Medicine. a disease causing a softening of the muscle of the heart.
cardiomegaly
Medicine. an abnormal enlargement of the heart.
cardiomyopathy
Medicine. a general term designating the early stages of diseases of heart muscles.
cardiopaludism
Medicine. a heart disease caused by malaria and marked by increases in heart rhythm and doubled beating.
cardiopathy
any disease or disorder of the heart. cardiopath, n. cardiopathic, adj.
cardiophobia
an abnormal fear of heart disease.
cardiopuncture
cardiocentesis.
cardioversion
Medicine. the restoration of proper heart rhythm by electrical shock.
carditis
an inflamed condition of the heart.
crotism
the condition of having a single (monocrotism), double (dicrotism), etc., heartbeat.
diastole
the rhythmic dilatation of the heart during which the muscle relaxes and the chambers fill with blood. Cf. systole. diastolic, adj.
dicrotism
the condition of having a doublé heartbeat. dicrotic, adj.
endocarditis
an inflamed condition of the endocardium, the membrane that lines heart chambers.
eurhythmy
an even pulsebeat. eurhythmic, adj.
fibrillation
the uncontrolled twitching of the muscular fibrils, especially of the cardiac muscles.
infarction
a condition in which a localized area of muscular tissue is dying or dead owing to insufficient supply of blood, as occurs in a heart attack.
monocrotism
the condition of having a single heartbeat. monocrotic, adj.
myocarditis
an inflamed condition of the muscular walls of the heart.
palpitation
1. rapid and irregular beating of the heart.
2. a trembling of the body, as from fear or anxiety.
pericarditis
an inflamed condition of the pericardium, the membrane that surrounds the heart.
systole
the rhythmic contraction of the heart, and especially of the ventricles, following each dilatation. Cf. diastole. systolic, adj.
tachycardia
abnormally rapid beating of the heart.
tricrotism
the condition of having three arterial beats for every one heartbeat, as in certain pulses. tricrotic, adj.
valvulitis
inflammation of a cardiac valve, usually caused by syphilis or rheumatic fever.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Heart." -Ologies and -Isms. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"Heart." -Ologies and -Isms. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/heart-0

"Heart." -Ologies and -Isms. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/heart-0

heart

heart the heart is traditionally regarded as the centre of a person's thoughts and emotions, especially love or compassion.

The heart is stylistically represented by two equal curves meeting at a point at the bottom and a cusp at the top; such hearts are emblematic of love.

Hearts are one of the four suits in a conventional pack of playing cards, denoted by a stylized red figure of a heart.
break someone's heart overwhelm someone with sadness.
have a heart of gold have a generous nature.
have one's heart in one's mouth be greatly alarmed or apprehensive.
heart of darkness a place of savagery and barbarism, from the title of Joseph Conrad's novel (1902).
Heart of Dixie an informal name for Alabama.
Heart of Midlothian a name for the old Edinburgh Tolbooth, or prison, taken by Scott as the title of a novel (1818), set in 18th-century Edinburgh and opening with the Porteous riot.
heart of oak the solid central part of an oak tree as the traditional timber for ships. The phrase was popularized by the 18th-century song, ‘Heart of oak are our ships, heart of oak are our men.’
heart of stone a stern or cruel nature.
heart's blood an archaic term for the blood, as being necessary for life; vital energy or force.
one's heart's desire a person or thing that one greatly wishes for.

See also cold hands, warm heart, faint heart never won fair lady, heartbeat, hearts, hope deferred makes the heart sick, please your eye and plague your heart, it is a poor heart that never rejoices, a song in one's heart, put a stout heart to a stey brae, the way to a man's heart, wear one's heart on one's sleeve.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." The Oxford Dictionary of Phrase and Fable. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." The Oxford Dictionary of Phrase and Fable. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart

"heart." The Oxford Dictionary of Phrase and Fable. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart

heart

heart A hollow muscular organ that, by means of regular contractions, pumps blood through the circulatory system (see circulation). The vertebrate heart has a thick wall (see myocardium) composed of a specialized muscle (see cardiac muscle); it is surrounded by the pericardium. Mammals have a four-chambered heart consisting of two atria and two ventricles; the right and left sides are completely separate from each other so there is no mixing of oxygenated and deoxygenated blood (see illustration). Oxygenated blood from the pulmonary veins enters the heart through the left atrium, passes to the left ventricle, and leaves the heart through the aorta. Deoxygenated blood from the venae cavae enters the right atrium and is pumped through the right ventricle to the pulmonary artery, which conveys it to the lungs for oxygenation. The tricuspid and bicuspid valves ensure that there is no backflow of blood. The contractions of the heart are initiated and controlled by the sinoatrial node (see pacemaker); in an average adult human the heart contracts about 70 times per minute. See also cardiac cycle; cardiac output.

The hearts of other vertebrates are similar except in the number of atria and ventricles (there may be one or two) and in the degree of separation of oxygenated and deoxygenated blood. Invertebrates, however, show great variation in the form and functioning of the heart.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." A Dictionary of Biology. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." A Dictionary of Biology. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/heart-0

"heart." A Dictionary of Biology. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/heart-0

heart

heart A muscular pump that causes blood to circulate. In invertebrates such as Arthropoda, Annelida, Mollusca, and Echinodermata, the heart is multichambered and occurs dorsally to the gut. In vertebrates, hearts are composed of cardiac muscle which is smooth in origin although striated in appearance, surrounded by the pericardium. There are three types of vertebrate heart structure: in fish there are two chambers, an atrium into which blood enters and a ventricle which expels blood into the circulatory system; in amphibians and most reptiles there are two atria and a single ventricle; in higher reptiles, such as Crocodilia and above, there are two atria and two ventricles. Whilst there is a relatively low blood pressure in fish and a single circulatory system, all tetrapods have a double circulatory system. See also CARDIAC CYCLE.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." A Dictionary of Zoology. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." A Dictionary of Zoology. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/heart

"heart." A Dictionary of Zoology. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/heart

Heart

Heart

Belief in the heart as a psychic structure dates to ancient times and stems from the characteristic responses of that organ to emotional crises. Some mystical writers have posited the idea of a subtle or spiritual heart center located slightly to the right of the physical heart.

In the Bible (Eccles. 10:2) it is said that the heart of the wise is at the right side and the heart of the foolish at the left. This proverb parallels the ancient Hindu yoga concept of the anahata chakra, or subtle heart center, which yogis have experienced as slightly to the right side in the body.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Heart." Encyclopedia of Occultism and Parapsychology. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"Heart." Encyclopedia of Occultism and Parapsychology. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/heart-0

"Heart." Encyclopedia of Occultism and Parapsychology. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/heart-0

heart

heart (hart) n. a hollow muscular cone-shaped organ, lying between the lungs, with the apex directed downwards, forwards, and to the left. It is divided by a septum into separate right and left halves, each of which is divided into an upper atrium and a lower ventricle (see illustration overleaf). Deoxygenated blood is pumped to the lungs via the right atrium and ventricle; newly oxygenated blood is pumped out to the body via the left atrium and ventricle. The direction of blood flow within the heart is controlled by valves.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." A Dictionary of Nursing. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." A Dictionary of Nursing. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/heart

"heart." A Dictionary of Nursing. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/heart

heart

heart Muscular organ that pumps blood through the body. In humans, the heart muscle is located behind the sternum. Divided longitudinally by a muscular wall, the right side contains only deoxygenated blood, the left side only oxygenated blood. The pulmonary artery carries deoxygenated blood from the heart to the lungs. Each side divides into two chambers, an atrium and a ventricle. The average heart beat rate for an adult at rest is 70–80 beats per minute.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." World Encyclopedia. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." World Encyclopedia. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/heart-0

"heart." World Encyclopedia. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/heart-0

heart

heart bodily organ, regarded as the centre of vital functions, the seat of affections, etc. OE.; dear person; innermost part XIII; vital part; †stomach XVI. OE. heorte = OS. herta (Du. hart), OHG. herza (G. herz), ON. hjarta, Goth. hairtō :- Gmc. *χartan-, -ōn. The IE. base *k̂ḗrd- *k̂rd is repr. also by Gr. kěr, kardíā, L. cor, cord-, Lith. širdìs, OIr. cride, etc.
Hence hearten XVI.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart-2

"heart." The Concise Oxford Dictionary of English Etymology. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart-2

Heart (river, United States)

Heart, river, 180 mi (290 km) long, rising in the low prairie country near the Little Missouri River, SW N.Dak., and flowing E to the Missouri at Mandan, N.Dak. The Heart Butte and Dickinson dams, irrigation and flood control units built by the U.S. Bureau of Reclamation as part of the Missouri River basin project, have created the region's largest lakes, which are major recreation areas.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Heart (river, United States)." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"Heart (river, United States)." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/heart-river-united-states

"Heart (river, United States)." The Columbia Encyclopedia, 6th ed.. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/heart-river-united-states

heart (in anatomy)

heart, muscular organ that pumps blood to all parts of the body. The rhythmic beating of the heart is a ceaseless activity, lasting from before birth to the end of life.

Anatomy and Function

The human heart is a pear-shaped structure about the size of a fist. It lies obliquely within the chest cavity just left of center, with the apex pointing downward. The heart is constructed of a special kind of muscle called myocardium or cardiac muscle, and is enclosed in a double-layered, membranous sac known as the pericardium. A wall of muscle divides the heart into two cavities: the left cavity pumps blood throughout the body, while the right cavity pumps blood only through the lungs. Each cavity is in turn divided into two chambers, the upper ones called atria, the lower ones ventricles. Venous blood from the body, containing large amounts of carbon dioxide, returns to the right atrium. It enters the right ventricle, which contracts, pumping blood through the pulmonary artery to the lungs. Oxygenated blood returns from the lungs to the left atrium and enters the left ventricle, which contracts, forcing the blood into the aorta, from which it is distributed throughout the body. In addition, the heart employs a separate vascular system to obtain blood for its own nourishment. Two major coronary arteries regulate this blood supply.

Cardiac Cycle

Blood flows through the heart in one direction only. It is prevented from backing up by a series of valves at various openings: the tricuspid valve between the right atrium and right ventricle; the bicuspid, or mitral, valve between the left atrium and left ventricle; and the semilunar valves in the aorta and the pulmonary artery. Each heartbeat, or cardiac cycle, is divided into two phases. In the first phase, a short period of ventricular contraction known as the systole, the tricuspid and mitral valves snap shut, producing the familiar "lub" sound heard in the physician's stethoscope. In the second phase, a slightly longer period of ventricular relaxation known as the diastole, the pulmonary and aortic valves close up, producing the characteristic "dub" sound. Both sides of the heart contract, empty, relax, and fill simultaneously; therefore, only one systole and one diastole are felt. The normal heart has a rate of 72 beats per minute, but in infants the rate may be as high as 120 beats, and in children about 90 beats, per minute. Each heartbeat is stimulated by an electrical impulse that originates in a small strip of heart tissue known as the sinoatrial (S-A) node, or pacemaker.

Advances in Cardiology

One of the important advances in cardiology is the artificial pacemaker used to electrically initiate a normal heartbeat when the patient's own pacemaker is defective (see arrhythmia); it may be surgically implanted in the patient's body. Similarly, an internal defibrillator may be implanted to deliver an electrical shock to the heart in order to stop certain forms of rapid heart rhythm disturbances. Another familiar tool of the cardiologist is the electrocardiograph (EKG), which is used to detect abnormalities that are not evident from a physical examination (see electrocardiography).

One of the most important advances in heart surgery during the 1960s was the transplantation of the healthy heart immediately after the death of an individual (the donor) to a recipient suffering from incurable heart disease (see transplantation, medical). In the 1980s new advances in the design and construction of an artificial heart—both the entire organ and such parts as the valves and large blood vessels—showed some promise in treating cardiovascular disease (see heart, artificial), but the limited success that has characterized artificial heart implantation thus far has led many experts to question the efficacy of such measures. Although the artificial heart has often been used as a temporary measure until a permanent human donor heart can be located, a number of recipients have not fared well, even for a limited duration. In addition, it is often unclear how long the recipient will have to wait for a donor. Proponents of the artificial heart hope that technological advances will allow the permanent replacement of human hearts with artificial ones.

See circulatory system; heart disease.

See J. Peto, The Heart (2005).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart (in anatomy)." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart (in anatomy)." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/heart-anatomy

"heart (in anatomy)." The Columbia Encyclopedia, 6th ed.. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/heart-anatomy

heart

heart Usually from ox, lamb, pig, or sheep; a 150‐g portion is a rich source of protein, niacin, iron, and vitamins B1 and B2, also, unusually for a meat product, a good source of vitamin C; contains about 9 g of fat, of which half is saturated; supplies 270 kcal (1130 kJ).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." A Dictionary of Food and Nutrition. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." A Dictionary of Food and Nutrition. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/heart

"heart." A Dictionary of Food and Nutrition. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/heart

heart

heartapart, apparat, art, baht, Bart, Barthes, cart, carte, chart, clart, dart, Eilat, fart, ghat, Gujarat, Gujrat, hart, Harte, heart, heart-to-heart, impart, Jat, kart, kyat, Maat, Mansart, mart, outsmart, part, quarte, salat, savate, Scart, smart, start, tart, zakat •Hobart • wallchart • flow chart •Bogart • Stuttgart • Earhart •greenheart • sweetheart • Leichhardt •Reinhardt • Bernhardt • handcart •Descartes • dogcart • go-kart •pushcart • dustcart • rampart •forepart • underpart • Bonaparte •counterpart • Bundesrat • Robsart •Mozart • Hallstatt • kick-start •push-start • upstart

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"heart." Oxford Dictionary of Rhymes. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

"heart." Oxford Dictionary of Rhymes. . Encyclopedia.com. (August 20, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart-0

"heart." Oxford Dictionary of Rhymes. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/heart-0