Heart

The heart may also be illustrated as an icon (♥), symbolizing love. For a list of Melbourne Cup winning horses see List of Melbourne Cup winners. It can vary from one to four chambers (2 atria and 2 ventricle). In 2000 it was estimated that 80 percent of the adult Australian population placed a bet on the race that year [2]. Different species have different heart chambers. In Melbourne and surrounding areas, the race day is a public holiday, but around the country a majority of people watch the race on television and gamble, either through direct betting or participating in workplace cup "sweeps". It resembles venison in structure and taste. Raceday fashion has occasionally drawn almost as much attention as the race itself, The miniskirt received worldwide publicity when model Jean Shrimpton wore one on Derby Day during Melbourne Cup week in 1965.

They are counted among offal, but being a muscle, the taste of heart is much more like regular meat than that of other offal. The requirement for elegant hats almost single-handedly keeps Melbourne's milliners in business. The hearts of cattle, sheep, pigs and certain fowl are consumed as food in many countries. 'Fashions On The Field' is a major focus of the day, with substantial prizes awarded for the best-dressed male and female racegoers. The earthworm has a series of multiple primitive hearts. For which in 2005 Makybe Diva truly left her mark in history by winning the Cox Plate only 9 days before going on to win the Melbourne Cup. The Gray Whale's heart beats 9 times per minute, Harbour Seal 10 when diving, 140 when on land, elephant 25, human 70, sparrow 500, shrew 600, and hummingbird 1,200 when hovering. They regard the Cox Plate, a 2,040 metre Weight for Age race, as a true indication of the best horses in Australia.

See "Early development" above for information about the early human heart rates. Racing purists and "serious" betters dislike the Cup, as the unusually long distance and handicap rules make the result highly unpredictable and allows mediocre horses to win. This is evident within a species as well, as the young beat their hearts faster than the adults. In the past, such weightings were in theory established to give each horse an equal chance of winning the cup, but in recent years the rules have been adjusted to that of a "quality handicap" where superior horses are given less severe weight penalties than would be the case under pure handicap rules. Smaller animals have faster heartbeats. Older horses are given more weight than younger ones, and weightings are further adjusted according to the horse's previous results. Birds and mammals show complete separation of the heart into two pumps, for a total of four heart chambers; it is thought that the four-chambered heart of birds evolved independently of that of mammals. The Melbourne Cup is run as a "handicap", in which the weight of the jockey, and riding gear is adjusted with ballast to a nominated figure.

The blood from the single ventricle is then pumped to both the lungs and the body tissues, an type of double circulation. A large rose bowl trophy was presented 1915-1918 and the current loving cup design was introduced in 1919. Blood from both the body and the lungs is pumped into the single ventricle, where unoxygenated and oxygenated blood may mix. It was a chalice centred on a long base which had a horse at each end. Amphibians and reptiles have a three-chambered heart: two atria and one ventricle. The last Melbourne Cup trophy manufactured in England was made for the 1914 event. The blood pumps through the gills and on to the the body tissues without returning to the heart. A silver plated base sporting three silver horses was added in 1888, but in 1891 the prize changed to being a 15 inch high, 24 inch long trophy showing a Victory figure offering an olive wreath to a jockey There were no races 1894-1898 because of a depression, and on resumption the trophy was in the form of silver galloping horse embossed on a 3 foot long plaque, although it was said to look like a greyhound by some people.

In fish, the system has only one circuit. It had two handles and an engraving of a horse race set at Flemington. The heart of fish have only two chambers: one atrium and one ventricle. The first Australian-made and gold trophy was introduced in 1876. If an automated external defibrillator is available, this device may automatically administer defibrillation if this is indicated. From 1867 to 1875, a silver trophy was presented showing "Alexander Taming the Horse" and a figure of a female with wings. If a person is encountered in cardiac arrest (no heartbeat), cardiopulmonary resuscitation (CPR) should be started, and help called. The first trophy was a gold watch, until a silver bowl manufactured in England, with two ornate handles with a horse and rider on top, was introduced in 1865.

See cardiac arrest for emergencies involving the heart. The trophy changed in appearance greatly over the years since the first trophy was awarded in 1861, with several of them featuring model horses. See also: Cardiology diagnostic tests and procedures. The winning trainer and jockey also receive a miniature replica of the cup and the strapper is awarded the Tommy Woodcock Trophy, named after the strapper of the incomparable Phar Lap. The transplant team was headed by Christiaan Barnard. The trophy currently awarded (since 1919) is a gold loving cup worth $75,000 at 2005 prices. At Groote Schuur Hospital in Cape Town, South Africa, 53-year-old Louis Washkansky on December 3, 1967 became the first human to receive a heart transplant (however he died 18 days later from double pneumonia). Trainer Lee Freedman said after the race, "Go and find the youngest child on the course, because that's the only person here who will have a chance of seeing this happen again in their lifetime.".

Nitroglycerin and other compounds that give off nitric oxide are used to treat heart disease as they cause the dilation of coronary vessels. Makybe Diva made history by becoming the only horse to win three in a row. Beta blockers are drugs that lower the heart rate and blood pressure and reduce the heart's oxygen requirements. The 2005 Melbourne Cup was held before a crowd of 106,479. If a coronary artery is blocked or narrowed, the problem spot can be bypassed with coronary artery bypass surgery or it can be widened with angioplasty. In 2004 Makybe Diva became the first mare to win consecutive cups, and also the first horse to win twice with different trainers, after David Hall moved to Hong Kong and transfered her to the Lee Freedman stables. Important diseases of the heart include:. She also won the Caulfield Cup, a 2400 metre race also held in Melbourne, and therefore has won the "Cups Double".

The study of diseases of the heart is known as cardiology. The 2001 the Melbourne Cup was won by New Zealand mare Ethereal, trained by Sheila Laxon, the first woman to formally train a Melbourne Cup winner. The heart also secretes ANF (atrial natriuretic factor), a powerful peptide hormone, that affects the blood vessels, the adrenal glands, the kidneys and the regulatory regions of the brain to regulate blood pressure and volume. The attraction for foreigners to compete, however, was the far less visible change to the new "quality handicap" weighting system. In the event of severe pathology, the Purkinje fibers can also act as a pacemaker; this is usually not the case because their rate of spontaneous firing is considerably lower than that of the other pacemakers and hence is overridden. Most have failed to cope with the conditions, with only Irish trainer Dermott Weld successful in 1993 with Vintage Crop and 2002 with Media Puzzle. The time taken for the wave to reach this node from the sinoatrial nerve creates a delay between contraction of the two chambers and ensures that each contraction is coordinated simultaneously throughout all of the heart. The race has undergone several alterations over the past decade, the most visible being the arrival of many foreign horses to contest the race in the last decade (notwithstanding the many winners from New Zealand including the famous Phar Lap.

Once the wave reaches the atrioventricular node, situated in the lower right atrium, it is conducted through the bundles of His and causes contraction of the ventricles. Many sympathetic owners boycotted the race which started with only seven horses, the smallest number in the history of the cup. The sinoatrial node, often known as the cardiac pacemaker, is located in the upper wall of the right atrium and is responsible for the wave of electrical stimulation (See action potential) that initiates atria contraction. Archer won again the following year, but because the owner's nomination form arrived late the next year, Archer was unable to contest a third cup. The rhythmic sequence of contractions is coordinated by the sinoatrial and atrioventricular nodes. A crowd of 4000 watched the race, although it has been suggested this was less than expected because of news reaching Melbourne of the death of explorers Burke and Wills. The heart's rhythmic contractions occur spontaneously, although the frequency or heart rate can be changed by nervous or hormonal influences such as exercise or the perception of danger. It has been said that the winner, Archer, walked 800km to the course from Nowra, New South Wales, but it is possible he travelled by ship.

This is in contrast with skeletal muscle, which requires either conscious or reflex nervous stimuli. Seventeen horses contested the first Melbourne Cup in 1861, racing for a gold watch and 170 pounds cash. Cardiac muscle is self-exciting. In 2005 a total of 383,784 race fans attended the Melbourne Cup Carnival annual event [1]. Finally complete cardiac diastole involves relaxation of the atria and ventricles in preparation for refilling with circulating blood. The event is one of the most popular spectator events in Australia, with over 110,000 people, some dressed in traditional formal raceday wear and others in all manner of exotic and amusing costumes, attending the race. The ventricular systole consists of the contraction of the ventricles and flow of blood into the circulatory system. Again, once all the blood empties from the ventricles, the pulmonary and aortic semilunar valves close. .

It is the closing of the valves that produces the familiar beating sounds of the heart, commonly referred to as the "lub-dub" sound due to the closing of the semilunar and atrioventricular valves. The present record holder is the 1990 winner Kingston Rule with a time of 3min 16.3sec. This prevents any backflow into the atria. This reduced the distance by 61ft 6in, and Rain Lover's 1968 race record of 3min.19.1sec was accordingly adjusted to 3min.17.9sec. Once the blood has fully left the atria, the atrioventricular valves, which are situated between the atria and ventricular chambers, close. The race was originally held over two miles, about 3,218 metres, but following Australia's adoption of the metric system in 1972 the current distance of 3200 metres was adopted. Every single beat of the heart involves a sequence of events known as the cardiac cycle, which consists of three major stages: atrial systole, ventricular systole and complete cardiac diastole. The atrial systole consists of the contraction of the atria and the corresponding influx of blood into the ventricles. It is generally regarded as the most prestigious "two-mile" handicap in the world.

The function of the heart is to pump blood around the body. The event has been held on the first Tuesday in November since 1861 by the Victoria Racing Club, on the Flemington Racecourse in Melbourne. See main page cardiac cycle. Billed as The race that stops a nation, it is for three-year-olds and over, and covers a distance of 3200 metres. The blood supply to the heart itself is supplied by the left and right coronary arteries, which branch off from the aorta. The Melbourne Cup is Australia's major annual thoroughbred horse race. The endocardium is a further layer of flattened epithelial cells and connective tissue which lines the chambers of the heart.

Beneath this is a much thicker myocardium made up of cardiac muscle. The first is the outer epicardium which is composed of a layer of flattened epithelial cells and connective tissue. The heart wall is made of three distinct layers. The contractile nature of the heart is due to the presence of cardiac muscle in its wall which can work continuously without fatigue.

Even though the ventricles lie below the atria, the two vessels through which the blood exits the heart (the pulmonary artery and the aorta) leave the heart at its top side. As the right ventricle needs to pump blood only to the lungs, it requires less muscle. The left ventricle is much more muscular (1.3 - 1.5 cm thick) than the right (0.3 - 0.5 cm thick) as it has to pump blood around the entire body, which involves exerting a considerable force to overcome the vascular pressure. Even the lungs take some of the blood supply from the aorta via bronchial arteries.

The left ventricle then pumps the blood through the aorta to the entire body. From the left atrium this newly oxygenated blood passes through the mitral valve to enter the left ventricle. The oxygenated blood then flows through pulmonary veins to the left atrium. In the lungs gaseous exchange takes places and the blood releases carbon dioxide into the lung cavity and picks up oxygen.

The right ventricle pumps the deoxygenated blood to the lungs, through the pulmonary artery. The blood then passes through the tricuspid valve to the right ventricle. Oxygen-depleted or deoxygenated blood from the body enters the right atrium through two great veins, the superior vena cava which drains the upper part of the body and the inferior vena cava that drains the lower part. On both sides, the lower ventricles are thicker than the upper atria.

The left side (see left heart) collects oxygenated blood from the lungs and pumps it out to the body. this happens through a process called diffusion. The function of the right side of the heart (see right heart) is to collect deoxygenated blood from the body and pump it into the lungs so that carbon dioxide can be dropped off and oxygen picked up. Finally complete cardiac diastole involves relaxation of the atria and ventricles in preparation for refilling with circulating blood.

Again, once all the blood empties from the ventricles, the pulmonary and aortic semilunar valves close. Valves between the atria and ventricles (atrioventricular valves) maintain coordinated unidirectional flow of blood from the atria to the ventricles.The ventricular systole consists of the contraction of the ventricles and flow of blood into the circulatory system. A septum divides the right atrium and ventricle from the left atrium and ventricle, preventing blood from passing between them. It consists of four chambers, the two upper atria (singular: atrium) and the two lower ventricles.

In normal adults, its mass is 250-350 g, but extremely diseased hearts can be up to 1000 g in mass. A stethoscope can be placed directly over the apex and count the beats. The apex is the blunt point at the base of the heart. It is enclosed by a sac known as the pericardium and is surrounded by the lungs.

In the human body, the heart is normally situated slightly to the left of the middle of the thorax, underneath the sternum (breastbone). [2]. There is no difference in male and female heart rates before birth. After the 15th week the deceleration slows reaching an average rate of about 145 (+/-25 bpm) bpm at term.

After peaking at about 9.2 weeks after the LMP, it decelerates to about 150 bpm (+/-25 bpm) during the 15 week after the LMP. [1]. This acceleration is approximately 3.3 bpm per day, or about 10 bpm every three days, an increase of 100 bpm in the first month. It then accelerates linearly for the first month of beating, peaking at 165-185 bpm during the early 7th week, (early 9th week after the LMP).

The human heart begins beating at a rate near the mother’s, about 75-80 beats per minute (bpm). The human embryonic heart (EHR) begins beating at approximately 21 days after conception, or five weeks after the last normal menstrual period (LMP), which is the date normally used to date pregnancy. . The term cardiac means "related to the heart", from the Greek kardia (καρδια) for "heart".

The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. Congenital heart defects. It is sometimes treated by implanting an artificial pacemaker. Cardiac arrhythmia is an irregularity in the heartbeat.

Endocarditis and myocarditis are inflammations of the heart. Congestive heart failure is the gradual loss of pumping power of the heart. A heart attack occurs when heart muscle cells die because blood circulation to a part of the heart is interrupted. Coronary heart disease is the lack of oxygen supply to the heart muscle; it can cause severe pain and discomfort known as Angina.