Why do most people say that the heart is on the left hand side of the chest cavity?
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The heart is located in the thoracic cavity between the lungs. If you were to draw a vertical line down the center of the chest, you would find that about two-thirds of the heart is on the left and one third on the right. The pointed end of the heart points to the left. So we can say that the heart is mostly on the left side.
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People who are left-handed are more dextrous with their left hand than with their right hand: they will probably also use their left hand for tasks such as personal care, cooking, and so on. Writing is not as good an indicater of handedness as it might seem, because many people who write with their right hand use their left for everything else.\n\n\nCauses of left-handedness\n\nNo one knows for certain why the human population is right-handed-dominant, but a number of theories have been proposed.\n\n\nEvolutionary theories: The warrior and his shield\n\nThis theory attempts to explain left-handedness by the position of a warrior's shield and his heart. Basically, since the heart is on the left side of the body, a warrior holding his shield with his left hand would be better able to protect his heart than if he held it with his right. Thus, a greater mortality of left-handers would explain the prevalence of right-handedness today.\n\n \nThe heart is not that far off center. While it is on the left side of the body, it is still fairly central in location. Protecting it with a shield would only result in a weak selective pressure, and there have not been enough generations since the bronze age. \n\n  \nIt predicts that more men would be right-handed than women. However, data indicates that more males are left-handed than females. \nAnalysis of ancient cave paintings indicate that humanity was right-handed long before the bronze age. \n\nBrain hemisphere division of labour\n\nThis is the most commonly accepted theory of handedness. The premise of this theory is that since both speaking and handiwork require fine motor skills, having one hemisphere of the brain do both would be more efficient than having it divided up. And since in most people, the left side of the brain controls speaking, right-handedness would prevail. It also predicts that left-handed people would have a reversed brain division of labour. Lastly, since other primates do not have a spoken language (at least of the type we have) there would be no stimulus for right-handed preference among them, and that is true.\n\n\nEnvironmental theories\n\nBirth stress \n\nLeft-handed people cringe at this theory, because its basic premise is that left-handedness is due to brain damage during the birth process. Unfortunately, some statistics do back this theory up.\n\nDifficult or stressful births happen far more commonly among babies who grow up to be left-handed or ambidextrous. Birth stress is also associated with a number of birth defects and complications, including cerebral palsy and autism.\n\n Throughout history and throughout the world, the level of medicine and technology to assist with childbirth has improved. In spite of that, the proportion of left-handed people has not decreased. (In a sense, it has increased because more people see left-handedness as the benign trait it is.) \n\nParental pressure\nThis theory explains right-handed dominance by claiming that since the parents who raised us are mostly right-handed, we came to be mostly right-handed and so on.
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The right lung has three lobes (superior, middle, and inferior from top to bottom), and the left only has two (superior and inferior).  \n\nA side note: this difference has been attributed to the fact that the heart resides a bit more in the left chest than the right, and three lobes plus the heart would be a bit too snug for the lungs or heart to function properly.
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The coronary arteries originate OUTSIDE of the heart, both left and right ostiums come from the aorta.\n  There are many within the heart such as the AV brandh of the right, the septals from the left as well as diagonals from the Left anterior descending and the om 1 and 2 from the circumlex artery.\n  Of the left mainstem is the left side which has the LAD and circumflex and intermediate.\n   From the right is the right coronary artery which has branches called the conus, AV, and then bifurcates to the PDA and pvl.
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Because the phrase is relative to your position. Similar to the way your left is always on your left no matter where you or others stand.
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Many, many generations ago, it was believed that there was a vein that ran from the left ring finger directly to the heart. Therefore, placing a wedding ring on that finger implied a direct link to the heart.
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It's a very good question. But it would be even better if you asked other way around. \n\nBecause, people who are left-handed are right. cz left side of the brain controls the muscles and also it is a bit faster than left.\n\nBut if you ask the other way around, that why many of us do it wrong? I really don't know. But can guess that its more cultural thing than anything else.\n\nhttp://www.coolquiz.com/trivia/explain/docs/lefthand.asp
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Sometimes it can be left.\nOther times it can cause infection or later pain.\nAlso sometimes it has invaded an artery it can travel to the heart or other area of the body and create all kinds of problems.
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The liver lies on the right side of the abdominal cavity beneath the diaphragm
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I'm not sure if this is enough info but...\nWhen the Left Atrium is full of blood, the heart muscle in the Left Ventricle relaxes so the muscles attached to the Mitral Valve open.
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You have an artery on both sides and a vein on the other (jugular) same as all parts of your body. One takes blood to the heart (vein) one back into the body full of oxygen (artery)
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The hands??? Really? I've usually heard it was the eyes. Once I heard it was the heart. Not the organ that pumps blood, but the part of you that can love and open up or close down.
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Left Anterior Descending Artery\n\nCause many times people get heartattacks due to blockage in this artery, and it happens both fast and unexpectedly.
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In the human body, the heart is normally situated slightly to the left of the middle of the thorax, underneath the sternum (breastbone). It is enclosed by a sac known as the pericardium and is surrounded by the lungs. The apex is the blunt point at the base of the heart. A stethoscope can be placed directly over the apex and count the beats. In normal adults, its mass is 250-350 g, but extremely diseased hearts can be up to 1000 g in mass. It consists of four chambers, the two upper atria (singular: atrium) and the two lower ventricles.\n\nA septum divides the right atrium and ventricle from the left atrium and ventricle, preventing blood from passing between them. 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. Again, once all the blood empties from the ventricles, the pulmonary and aortic semilunar valves close. Finally complete cardiac diastole involves relaxation of the atria and ventricles in preparation for refilling with circulating blood.\n\nThe 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. This happens through a process called diffusion. The left side (see left heart) collects oxygenated blood from the lungs and pumps it out to the body. On both sides, the lower ventricles are thicker than the upper atria.\n\nOxygen-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. The blood then passes through the tricuspid valve to the right ventricle. The right ventricle pumps the deoxygenated blood to the lungs, through the pulmonary artery. In the lungs gaseous exchange takes places and the blood releases carbon dioxide into the lung cavity and picks up oxygen. The oxygenated blood then flows through pulmonary veins to the left atrium. From the left atrium this newly oxygenated blood passes through the mitral valve (also called the bicuspid valve) to enter the left ventricle. The left ventricle then pumps the blood through the aorta to the entire body. Even the lungs take some of the blood supply from the aorta via bronchial arteries.\n\nThe 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. As the right ventricle needs to pump blood only to the lungs, it requires less muscle.\n\nEven 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.\n\nThe contractile nature of the heart is due to the presence of cardiac muscle in its wall which can work continuously without fatigue. The heart wall is made of three distinct layers. The first is the outer epicardium which is composed of a layer of flattened epithelial cells and connective tissue. Beneath this is a much thicker myocardium made up of cardiac muscle. The endocardium is a further layer of flattened epithelial cells and connective tissue which lines the chambers of the heart.\n\nThe blood supply to the heart itself is supplied by the left and right coronary arteries, which branch off from the aorta.
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The walls of the heart are made up of three layers, while the cavity is divided into four parts. There are two upper chambers, called the right and left atria, and two lower chambers, called the right and left ventricles. The Right Atrium, as it is called, receives blood from the upper and lower body through the superior vena cava and the inferior vena cava, respectively, and from the heart muscle itself through the coronary sinus. The right atrium is the larger of the two atria, having very thin walls. The right atrium opens into the right ventricle through the right atrioventicular valve(tricuspid), which only allows the blood to flow from the atria into the ventricle, but not in the reverse direction. The right ventricle pumps the blood to the lungs to be reoxygenated. The left atrium receives blood from the lungs via the four pulmonary veins. It is smaller than the right atrium, but has thicker walls. The valve between the left atrium and the left ventricle, the left atrioventicular valve(bicuspid), is smaller than the tricuspid. It opens into the left ventricle and again is a one way valve. The left ventricle pumps the blood throughout the body. It is the Aorta, the largest artery in the body, which originates from the left ventricle.
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The cardiovascular system is a closed system, meaning that blood remains inside the vessels no matter how small they are.  The process of diffusion drives oxygen, carbon dioxide, wastes and nutrients between the tissues and the blood inside the blood vessels-blood just goes around the body.  Humans have a 4-chambered heart: 2 ventricles and 2 atria (sing: atrium).  The atria receive blood and the ventricles "expel" the blood (pumps the blood away from the heart).  You can partition the heart into two sides (left and right), each with its own ventricle and atrium.   One side is for the systemic circulation (to the body) and the other is for the pulmonary circulation (to the lungs).  Blood (deoxygenated) from the body collects in the right atrium, which passes the blood to the right ventricle, which relays the blood to the pulmonary arteries (arteries to the lungs) to get oxygen and expel carbon dioxide.  Once the blood in the lungs acquires oxygen, it passes to the pulmonary veins and into the left atrium.  Then, the blood goes into the left ventricle and is pumped into the aorta (think of it as the largest artery in the body or like in the water supply, the main tube of water where all of the other tubes originate). From the aorta it goes to the arteries and then to the arterioles and the capillary networks (where gas exchange occurs).  After being depleted of oxygen, it goes to the venules to the veins then to the vena cavae and back into the right atrium and it goes around again. :-)
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Many but these are the most common\nshortness of breath\nnausea\npain in chest, a little on left side\npain in left arm\nextreme pressure on the chest or arm