how does the heart work to produce a beat?
105640
The heart cells are called myocytes that can contract.  Proteins inside the myocyte, actin and myosin, make this contraction possible.  Calcium ions are released very quickly (from the sarcoplasmic reticulum) and trigger the contraction. Then the heart relaxes and gets ready for the next beat.  The contraction is controlled from the top of the heart (the atria) and spreads down to the botton (the ventricles), like a water ripple through a pond but in this case it is through all the cells of the heart.  The coordinated contraction then results in blood being pumped into the lungs and forward through the body.\n\nIf you need a more detalied description let me know.  This is the basic idea though.  The billions of cells of the heart are coordinated to result in proper heart beats.
1074878
In the human anatomy, we have 2 atria and 2 ventricles.  The ventricle structure works like a bladder in a water pump to create the pressure to push the blood out into the circulatory system.  After the ventricle contracts and is empty, a supply of blood is needed to refill for the next contraction.  Think of the atrium as a bucket ready to dump into the ventricle.  It allows fast refill at low pressure.
869365
There is not a voluntarty "part" of your heart.  The heart is controlled by the automic nervous system, comprised of the sympathetic and parasympathetic, which are your "fight or flight" portions of your nervous system.  Your somatic nervous system controls the voluntary muscles, like the skeletal muscles.\n\nCheck this site out:  http://163.1.0.40/wfsa/html/u05/u05_010.htm
467229
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.
16005
The body's circulation has two parts, with the heart acting as a double pump. Blood from the right side pump is dark red (bluish) and low in oxygen. It travels along pulmonary arteries to the lungs where it receives fresh supplies of oxygen and becomes bright red. It flows along pulmonary veins back to the heart's left side pump.\n\n \n\n \n\n\nBlood leaves the left side of the heart and travels through arteries which gradually divide into capillaries. In the capillaries, food and oxygen are released to the body cells, and carbon dioxide and other waste products are returned to the bloodstream.The blood then travels in veins back to the right side of the heart, and the whole process begins again.
974511
The heart is what pumps blood throughout the body, keeping all organs functioning. Blood flows to the body through arteries and blood flows back to the heart through veins. Its all one big system - the circulatory system.
16348
The heart is a double pump with four chambers, each separated by valves that only permit blood to flow in one direction. Basically, the right side of the heart pumps deoxygenated blood to the lungs, while the left side pumps oxygenated blood to the body.
78046
the one of brain's function in human physiology is that on the certain segment of brain controls heart rate. That means brain can order the heart to keep on pump in order to stay alive. \n\nWith each beat, the heart continuously communicates with the brain and body via the nervous system, hormonal system, bioelectromagnetic interactions, and other pathways.
417595
from what i rememeber the heart makes two sounds, a heavy-thick (like bass) called 'dup' and a small thinner pitched one called 'lup'.\nthe 'dup' is due to the closure of the atrioventricular valces during systole (contraction - when the blood is pumped from the ventricles (which are the down compartment of the hearts) to the atriums (which are the upper ones). after this happens, the blood is passed through the aorta which has a valve to make the blood not go backwards (called semi-lunar valve) and when these valve close it makes the 'lup' sound !!! so it goes like this Lup-dup lup-dup lup-dup .............
303652
All right, I'm first going to explain, briefly, the structure of the cardiovascular system, and then I'll move on to how the blood transports oxygen specifically.\n\nYour heart pumps blood from the right ventricle to your lungs, where it exchanges carbon dioxide for oxygen, and then continues to your left atria. The left atria pumps the blood to the left ventricle, which pumps blood through your arteries  to your capillaries, where the oxygen is released so that cells can use it. Carbon dioxide is picked up, and the blood continues to the veins, and back to the right atria.\n\nNow, your blood contains red blood cells, which contain two important molecules, hemoglobin and myoglobin. Both have a high affinity for oxygen, so, in your lungs, where there is a high oxygen concentration, oxygen binds to each of these two molecules (until the equilibrium point is reached). The red blood cells are pumped throughout the body. \n\nIn the body, the concentration of oxygen is lower than in the surrounding atmosphere, so the amount of hemoglobin (and myoglobin) which is binding oxygen decreases until it reaches the new equilibrium point. Active tissues use oxygen quickly, forming lots of CO2, which enters the blood, and is converted to carbonic acid by red blood cells, using the enzyme carbonic anhydrase. The change in pH lowers the affinity of hemoglobin for oxygen, so more oxygen is released from other red blood cells near working tissues. The carbonic acid is released back into the blood from red blood cells, where it dissociates into a proton (H+) and a bicarbonate ion. It travels through the blood back to the lungs, where it is converted back into CO2, and diffuses across the transport surfaces of the lungs due to the concentration gradient. Then the cycle starts over.
244732
the heart has four chambers,two atria and two venticles. during normal heart rate the atrial rate is the same as the ventricular rate.sometimes it so happens that cycles of short circuits start to take place in the heart muscle. the rate of atrial contraction hence increases. atrial flutter is when the atria are contracting at the rate of 200-350 and atrial fibrillation when the atria are contracting at the rate more than 500.
128249
- Are you talking about the the love or romance...?\n- the work of HEARTS is nothing but controlling your blood circulation.\n- But your thinking and attitudes are controlled by the signals generated in the Brain.\n- lol\n---------------
1003119
look at this 3D pic then read\n\nhttp://library.thinkquest.org/C003758/rotate.htm\n\nIn the human body, the heart is normally situated slightly to the left of the middle of the thorax, underneath the sternum (breastbone). The heart is usually felt to be on the left side because the left heart (the left part of the heart) is stronger (it pumps the blood out). The heart is enclosed by a sac known as the pericardium and is surrounded by the lungs.Betwen the pericardium and the heart there is a serous fluid to reduce friction during heart contractions. 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 (8-11 oz), but extremely diseased hearts can be up to 1000 g (2 lb) in mass. It consists of four chambers, the two upper atria (singular: atrium ) and the two lower ventricles. On the right is a picture of a fresh human heart which was just removed from a 64 year old British gentleman. The mass for a thin white male is usually 270-300 grams (9-11 ounces) with little fat.\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 (pulmonary circulation)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 (systemic circulation). On both sides, the lower ventricles are thicker than the upper atria.\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 which drains the portal cyrculation too full with nutrients to nourish the body. 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 which is called external respiration. 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, which is 1.3 - 1.5 cm (.5-.6 in) thick, than the right, 0.3 - 0.5 cm ( .1-.2 in) 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 epi
205523
The heart rate would slow to conserve energy also each heart beat would be more efficient due to vasoconstriction of the extremities. At very low temperatures the body starts to decide which parts are more important than others to keep alive. It all comes down to the brain and the heart.
413091
Frogs have a THREE chambered heart, not two. Oxygen poor blood flows from right atrium to the ventricle where it is pumped to the lungs and skin to pick up oxygen. Next the blood flows back to the heart, collecting in the left atrium. It them flows to the ventricle and is pumped to the body, dropping off the oxygen. This oxugen poor blood flows back onto the right atrium and it begins again.\n\nThis process is simular in humans except we have two ventricles, and do not breath through or skin as much so the right ventricle pumps to lungs only.
512352
The heart is a fist-sized, muscular organ that pumps blood through the body. Oxygen-poor blood enters the right atrium of the heart (via veins called the inferior vena cava and the superior vena cava). The blood is then pumped into the right ventricle and then through the pulmonary artery to the lungs, where the blood is enriched with oxygen (and loses carbon dioxide). The oxygen-rich (oxygenated) blood is then carried back to the left atrium of the heart via the pulmonary vein. The blood is then pumped to the left ventricle, then the blood is pumped through the aorta and to the rest of the body. This cycle is then repeated. Every day, the heart pumps about 2,000 gallons (7,600 liters) of blood, beating about 100,000 times. enchantedlearning.com
137626
"The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to (and stimulate) the myocardium (muscle of the heart). When the myocardium is stimulated, it contracts. It is the ordered stimulation of the myocardium that allows efficient contraction of the heart, thereby allowing blood to be pumped to the body.\n\nUnder normal conditions, electrical activity is spontaneously generated by the SA node. This electrical impulse is propagated throughout the right and left atria, stimulating the myocardium of the atria to contract. The conduction of the electrical impulse throughout the atria is seen on the ECG as the P wave."\n\n"An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart in the form of a continuous strip graph."\n\n"An ECG measures the electrical potential between leads placed on various points of the body."\n\n"The leads measure the average electrical activity generated by the summation of the action potentials of the heart at a particular moment in time."