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From Wikipedia

Human heart

The human heart is a muscular organ that provides a continuous bloodcirculation through the cardiac cycle and is one of the most vital organs in the human body. The heart is an organ but made up of a collection of different tissues. It is divided into four main chambers: the two upper chambers are called the left and right atria and two lower chambers are called the right and left ventricles.There is a thick wall of muscle separating the right side and the left side of the heart called the septum. Normally with each beat the right ventricle pumps the same amount of blood into the lungs that the left ventricle pumps out into the body. Physicians commonly refer to the right atrium and right ventricle together as the right heart and to the left atrium and ventricle as the left heart.

The electric energy that stimulates the heart occurs in the sinoatrial node, which produces a definite potential and then discharges, sending an impulse across the atria. In the atria the electrical signal move from cell to cell while in the ventricles the signal is carried by specialized tissue called the Purkinje fibers which then transmit the electric charge to the myocardium

The human heart and its disorders (cardiopathies) are studied primarily by cardiology.

Structure

The human heart has a mass of between 250 and 350 grams and is about the size of a fist.

It is enclosed in a double-walled protective sac called the pericardium. The superficial part of this sac is called the fibrous pericardium. This sac protects the heart, anchors its surrounding structures, and prevents overfilling of the heart with blood.

The outer wall of the human heart is composed of three layers. The outer layer is called the epicardium, or visceral pericardium since it is also the inner wall of the pericardium. The middle layer is called the myocardium and is composed of muscle which contracts. The inner layer is called the endocardium and is in contact with the blood that the heart pumps. Also, it merges with the inner lining (endothelium) of blood vessels and covers heart valves.

The human heart has four chambers, two superior atria and two inferior ventricles. The atria are the receiving chambers and the ventricles are the discharging chambers.

The pathways of blood through the human heart are part of the pulmonary and systemic circuits. These pathways include the tricuspid valve, the mitral valve, the aortic valve, and the pulmonary valve. The mitral and tricuspid valves are classified as the atrioventricular (AV) valves. This is because they are found between the atria and ventricles. The aortic and pulmonary semi-lunar valves separate the left and right ventricle from the pulmonary artery and the aorta respectively. These valves are attached to the chordae tendinae (literally the heartstrings), which anchors the valves to the papilla muscles of the heart.

The interatrioventricular septum separates the left atrium and ventricle from the right atrium and ventricle, dividing the heart into two functionally separate and anatomically distinct units.

Functioning

Blood flows through the heart in one direction, from the atria to the ventricles, and out of the great arteries, or the aorta for example. Blood is prevented from flowing backwards by the tricuspid,bicuspid, aortic, and pulmonary valve.

The heart acts as a double pump. The function of the right side of the heart (see right heart) is to collect de-oxygenated blood, in the right atrium, from the body (via superior and inferior vena cavae) and pump it, via the right ventricle, into the lungs (pulmonary circulation) so that carbon dioxide can be dropped off and oxygen picked up (gas exchange). This happens through the passive process of diffusion.

The left side (see left heart) collects oxygenated blood from the lungs into the left atrium. From the left atrium the blood moves to the left ventricle which pumps it out to the body (via the aorta).

On both sides, the lower ventricles are thicker and stronger than the upper atria. The muscle wall surrounding the left ventricle is thicker than the wall surrounding the right ventricle due to the higher force needed to pump the blood through the systemic circulation.

Starting in the right atrium, the blood flows through the tricuspid valve to the right ventricle. Here, it is pumped out of the pulmonary semilunar valve and travels through the pulmonary artery to the lungs. From there, blood flows back through the pulmonary vein to the left atrium. It then travels through the mitral valve to the left ventricle, from where it is pumped through the aortic semilunar valve to the aorta and to the rest of the body. The (relatively) deoxygenated blood finally returns to the heart through the inferior vena cava and heavy metal band Accept. Although the group had recorded before at Dierks-Studios, this was the first album produced by Dieter Dierks himself. This album was a cautious attempt to crack the lucrative American market with more accessible songcraft and emphasis on hooks and melodies. Although critically panned at the time, today Metal Heart is often considered by fans as one of the band's best records.[http://www.martinpopoff.com/html/yeold_archives/accept.html]

It contains several of their classic songs such as "Metal Heart" and "Living for Tonite". The band also makes a detour into jazz territory with the unusual song "Teach Us to Survive".

Wolf Hoffmann explained the concept behind the album: "We had read an article that someone was working on an artificial heart and that one day everybody is going to have a computerized heart. It talked, in general terms, about how more and more of humanity gets sucked out of the daily life and more and more replaced by machine. It's not a new thing now, but then it was new. Humans versus machine, was the general vibe of the record." The original cover concept was for a hologram metal heart image, until budget considerations resulted in a traditional cover. But fittingly for the futuristic theme of the album, Metal Heart was the first Accept album to be digitally recorded.[http://web.archive.org/web/20020215044049/wolfhoffmann.com/html/metalheart.html]

Wolf recalls Dieter Dierks as a very demanding producer: "We would do some pieces several dozen times trying to capture what he had in his mind for a specific section," adding: "Each song we tried different combinations of guitars, mic'ing and even strings!" [http://web.archive.org/web/20020215044049/wolfhoffmann.com/html/metalheart.html]

The song "Metal Heart" is well known for containing the cover of two famous classical themes: Tchaikovsky's Slavonic March (in the intro) and Beethoven's Für Elise in the main riff and solo. This song was covered in 1998 by Norwegian Black Metal band Dimmu Borgir. "I had no idea it would become as popular as it did," Wolf remembers of his contribution to the song.[http://web.archive.org/web/20020215044049/wolfhoffmann.com/html/metalheart.html]

"Midnight Mover", about a drug dealer, is one of the more commercial songs on the album and was selected for a memorable music video that anticipates the bullet time filming technique by a full decade. "Just ahead of our time again!" jests Wolf.[http://web.archive.org/web/20020215044049/wolfhoffmann.com/html/metalheart.html]

Despite the more commercially appealing sound of the album, it fell short of the sales figures of its predecessor Balls to the Wallin America. Udo remembers theBreakerthrough Metal Heart era as the time when the band got along best together.[http://www.getreadytorock.com/pure_metal/udo_interview.htm] Thus this would turn out to be the last album of Accept's golden era, as cracks were soon to appear in the band's solidarity.

The digitally remastered CD edition includes two live bonus tracks "Love Child" and "Living for Tonite", both taken from the album Kaizoku-Ban.

Track listing

  1. "Metal Heart" – 5:19
  2. "Midnight Mover" – 3:05
  3. "Up to the Limit" – 3:47
  4. "Wrong Is Right" – 3:08
  5. "Screaming for a Love-Bite" – 4:06
  6. "Too High to Get It Right" – 3:47
  7. "Dogs on Leads" – 4:23
  8. "Teach Us to Survive" – 3:32
  9. "Living for Tonite" – 3:33
  10. "Bound to Fail" – 4:58

Credits

Charts

Album - Billboard (North America)



From Yahoo Answers

Question:Please use terminology and dont put it too stupid but dont make it to complicated. Please the path in all the 4 parts of the heart the right and left atria and the right and left ventricle.

Answers:A About 99 percent of the heart's muscle layer (myocardium) consists of muscle cells that contract in response to electrochemical signals (see "The Heart Is a Muscle, Too," vol. 6, no. 2). About 1 percent of the muscle layer is made up of specialized cells known as the conduction system, similar to the wiring in a mechanical device. These "wiring" cells control the rate and rhythm of the heartbeat by controlling the rate and direction of electrical impulses as they go through the heart (see illustration). The heart's "master pacemaker" is the sinoatrial (SA) node, which sits high in the right atrium, one of the two upper chambers of the heart. The SA node is a little like a car's battery. Without a functioning battery, the car's engine won't start, even if it's in fine condition. Without a working SA node, the heart won't beat at a normal rate, even if it's otherwise healthy. But unlike a car, which has only one battery, the heart has auxiliary pacemaker sites that can take over for a dead SA node. The problem is that they usually set a pace that's considerably slower than the master pacemaker. From the SA node, electrical impulses quickly spread through the right and left atria via muscle cells in the myocardium. Experts disagree about whether there are also specialized conduction pathways in the atria. The next stop for the electrical impulses is the atrioventricular (AV) node, low in the right atrium. Here, impulses are delayed for about a 10th of a second, just long enough to allow the atria to contract and add blood to the heart's lower chambers -- the ventricles -- before the ventricles get the signal to contract. (The ventricles have mostly filled with blood before the atria contract, but atrial contraction adds more.) It's the ventricles that are the most crucial part of the working myocardium, responsible for pumping blood to the lungs and to the rest of the body. The impulses then pass into the ventricles, where they first meet the common bundle, also known as the bundle of His. The common bundle is like a telephone cable and transmits impulses from the AV node to the rest of the ventricles. It divides into two thinner "cables," known as the left and right bundle branches. The bundle branches divide into still thinner cables called Purkinje fibers, which transmit impulses to all parts of the ventricles. After leaving the Purkinje fibers, impulses travel from muscle cell to muscle cell to all cells of the ventricular muscle layer. The cells in the lower part of each ventricle contract slightly earlier than the cells in the upper parts, which helps eject blood from the ventricles, in the same way that toothpaste is emptied from the tube from the bottom up. The whole process normally takes a fraction of a second, with all cells contracting nearly simultaneously. The process can be assessed with an electrocardiogram (EKG), a test in which electrodes applied to the skin indirectly measure the path of impulses as they travel through the heart.

Question:I am a 51 year old female, with high blood pressure since age 14, I was smoking about 1/2 pack cigarettes daily for 25 years. I have now stopped. For about a month I have been fatigued, short of breath just walking to my mailbox, tightness in chest, went to MD was sent to ER, stayed overnight then, I went to cardiologist and underwent EKG, Thallium Study Stress Test, and left heart catheterization,coronary angiography, lv gram. I was told to quit smoking of course, and I did. I really don't understand my results of the test. I still am very fatigued,short of breath, and left chest tightness, more so when up doing anything. My results were abnormal EKG,normal sinus rhythm. Q waves from v1 to v3 suggestive of old anterior wall myocardial infarction. Three sets of cardiac isoenzymes are negative. Angiography:The left ventriculogram showed hyperdynamic LV:EF around 70%. No gradient on catheter pullback, no angiographic MR noted. Left main coronary artery has about 20% eccentric lesion. Circumflex is a tortuous vessel, has no significant stenosis. LAD is also tortuous vessel in the distal segment, a proximal and mid vessel looks okay: distal vessel has about 10-20% diffuse disease.RCA also has about 10-20% disease in the proximal segment, tortuous vessel. Conclusions 1. Minimal coronary disease 2. Normal LV systolic function. My doctor told me I have a stiff heart, and to quit smoking, after the angiography, said he would treat with medication. Upon leaving I ask nurse about prescription and she told me he would give that to me at my follow up visit which was still 3 weeks away. I called his office and was told at this time he did not want to prescribe anything. My question is, can you explain these results to me in laymens terms so I can understand more what is going on with my heart. Also, I am still having all the symptoms I had before the test are they just something I will have to learn to live with? Or could these symptoms be caused from something else that can be treated. I am just at a stand still. I still feel as lousy as I did before all the testing, and probably more frustrated. My family history is my mother had a enlarged heart, my father at 55 had a triple bypass, then 7 years later had a heart transplant which he lived with for 15 years, then died of a stroke. Both parents had high blood pressure also, neither one ever smoked.Any thing you could explain to me would be helpful.

Answers:Basically, you have high cardiovascular risk factors (high blood pressure, strong family history of heart attack/ stroke, significant smoking history) which means that you have a high risk of having a heart attack, stroke, or peripheral vascular disease (disease of arteries in peripheries such as legs). Indeed, you have already had a heart attack and as such some of your heart muscle has died. The angiogram showed that you had disease of your arteries supplying your heart muscle (due to above risk factors), but it was not bad enough to perform surgery (bypass). The shortness of breath is most certainly due to the heart attack and you my also have a degree of emphysema due to your smoking history. You need regular exercise. There are specific fitness classes that deal with individuals like yourself and your dr should be able to tell you where to go. You should be on minimum, an ACE inhibitor, aspirin, beta blocker and statin for life. If you are not, then your dr should have a bloody good reason why. Good luck.

Question:Which of the following affect CO, and which affect PR? Why? Blood volume- the volume of the blood affects the pulse rate because the thicker the blood Heart rate Vasoconstriction Angiotensin II Aldosterone Epinephrine Histamine CO= cardiac output PR= Pulse rate 10 points to best answer

Answers:Heart rate and pulse rate are usually the same Increase in HR increases CO (CO = HR x stroke volume) Vasoconstriction decreases cardiac output (more resistance) Angiotensin II causes vasoconstriction Aldosterone casuses salt and water retention Epinephrine increases heart rate and CO Histamine causes vasodilatation

Question:please help me 10 grade homework

Answers:Look down at your own arm. What is taking blood away from your heart to your fingers. Then where does O2 exchange occur between that and what brings it back to your heart. Sorry, wouldn't feel right just answering.

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