please describe what r on t pheneomenon is? how it happens in the heart?
80523
For the sake of simplicity (I hope)  The normal electrical impulse begins in the sinus node of the atria..."p" wave Both atria contract and the electrical pulse passes on to   the ventricle...QRS wave and the ventricals contracts. The heart rests and repolarizes...this is the "T" wave.  If there is a true "R" on "T" complex...this is bad....the "R" is depolarizing as the "T" is trying to repolarize ....kinda like a premature beat before the heart is ready for it....a person can go into a bad arrhythmia like V-Fib.  This can happen when there is truely an "R" on "T" complex...often it is misread.
1078725
Systole refers to the active, ejection phase of the cardiac cycle, when the heart muscle forcefully contracts, ejecting blood out of the ventricles into the pulmonary artery and aorta. Diastole refers to the passive, relaxation phase of the cardiac cycle, when the heart's muscular walls relax, allowing the ventricles to fill with blood from the atria, pulmonary veins and vena cavae, in preparation for the next cycle.\n    Ventricular contraction during systole causes blood to leave the heart under high pressure, which is propagated as a pressure (pulse) wave throughout the arterial system. If our arteries were rigid pipes, then when the heart muscle relaxed during ventricular diastole, the blood pressure within the arteries would also drop close to zero. But since our arteries have walls that are highly elastic, the walls stretch and increase in diameter in response to the high pressure pulse wave of systole. Then during diastole, the arterial walls snap back to "normal" like a rubber band that's actively stretched (systole) and then allowed to passively return to normal (diastole). This passive contraction of the arterial walls, due to their elasticity, maintains positive pressure within the arteries during diastole, maintaining blood flow throughout the entire cardiac cycle. Thus, arterial blood pressure varies throughout the cardiac cycle: The maximum is the systolic pressure, and the minimum is the diastolic pressure.
138775
I found this great website http://www.yourpracticeonline.com.au/showcase.html\n\nIf you scroll right down to the bottom of the page there is a table in white, with a column labelled Heart, then under that click on the Heart Anatomy link. Sorry can't send you direct link - but this opens up a window with a superb anamation you can click around and even move around a 3d model of the heart. Then if you go through the presenation all the main items of the heart are shown.
154428
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.
861682
you wont have to ask that question. you will know when it happens to you. your whole body will feel it, every cell , cant think of nothing else.
658727
Heart palpatations.  The heart beats irregularly when super excited.
524124
how do you the heart?
126493
I believe its when one or more of the muscles in the heart becomes oversized which in turn disrupts the functions of the heart.
609559
Picture\nhttp://en.wikipedia.org/wiki/Image:Heart-and-lungs.jpg\n\nDetail\nhttp://en.wikipedia.org/wiki/Heart
818925
http://en.wikipedia.org/wiki/Cardiovascular
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.
1060169
"Thickening of the walls is related to hypertension.  Systole occurs when the left ventricle of the heart is pumping the blood through the body.  Think of a water hose, when more force is applied by the water pump, more pressure is applied against the inner walls of the hose.  This is the same with the heart and arteries.  arteries are surrounded with muscles that contract and expand the artery to help maintain enough pressure to feed a sufficient quantity of blood to all of the cells of the body.\n\nJust like any muscle these muscles around the arteries get larger with increased use and increased resistance.  When these arteries thicken because of this muscle growth the inside area of the artery becomes smaller providing less of an area for the volume of blood.  this restricts the flow of blood and makes the heart beat harder and faster to deliver the required amount of oxygen containing blood to the cells.  This decrease in flow area also then allows plaque, and clotting blood to stick to the side of the artery further narrowing the flow and finally depriving blood to an area where it is needed, like the heart, and results in death of the cells of a particular organ, such as the heart.  Thus causing a "heart attack".\n\nsystole is the term used for describing the pressure against the artery wall when the heart is contracting.
1174202
It's like a pressure or shock wave. \nImagine the Hiroshima bomb of menstral cramps. Like that.
204857
If you're referring to the heart, then it is, as the others said, a premature atrial contraction.  What this means is that instead of the electrical impulse for the heartbeat being generated by the group of cells known as the sinus node (located in the upper part of the right atrium), it was generated by some other "rogue" spot in the atrium.  This "rogue" spot fires its impulse sooner than the sinus node would have, hence the term "premature".
887298
Nobody answered your question.  =(  \nMost likely because of the minor spelling mistake.\n\nI'll assume that you are asking endergonic and exergonic rxn question.\n\nENDERGONIC means that energy is required to make the rxn occur.\nEXERGONIC means that energy is released as the rxn occurs.\n\nTherefore:\n\nSILVER TARNISHING IS AN EXERGONIC RXN:\nSilver tarnishing is a spontaneous process.  Ag + O2 ---> Ag2O.\nThis means that silver oxide (tarnished silver) is more stable or energetically favorable than its reactants.  Thus when something more stable is formed, Energy is Released.  \n\nPHOTOSYNTHESIS IS ENDERGONIC RXN: \nPhotosynthesis requires energy; and glucose- the product- has more energy than its reactants. In Biology, this process is called anabolic process because it builds big molecule, glucose, from small molecules, CO2 and H2O.
581711
The word you are looking for is Phosphene.\n\nPhosphenes are the light sensation you experience often from pressure/stimulus on your retina.
1155102
As we come to the vertebrates, we begin to find real efficiencies with the closed system. Fish possess one of the simplest types of true heart. A fish's heart is a two-chambered organ composed of one atrium and one ventricle. The heart has muscular walls and a valve between its chambers. Blood is pumped from the heart to the gills, where it receives oxygen and gets rid of carbon dioxide. Blood then moves on to the organs of the body, where nutrients, gases, and wastes are exchanged. However, there is no division of the circulation between the respiratory organs and the rest of the body. That is, the blood travels in a circuit which takes blood from heart to gills to organs and back to the heart to start its circuitous journey again.\n\nFrogs have a three-chambered heart, consisting of two atria and a single ventricle. Blood leaving the ventricle passes into a forked aorta, where the blood has an equal opportunity to travel through a circuit of vessels leading to the lungs or a circuit leading to the other organs. Blood returning to the heart from the lungs passes into one atrium, while blood returning from the rest of the body passes into the other. Both atria empty into the single ventricle. While this makes sure that some blood always passes to the lungs and then back to the heart, the mixing of oxygenated and deoxygenated blood in the single ventricle means the organs are not getting blood saturated with oxygen. Still, for a cold-blooded creature like the frog, the system works well. Humans and all other mammals, as well as birds, have a four-chambered heart with two atria and two ventricles. Deoxygenated and oxygenated blood are not mixed. The four chambers ensure efficient and rapid movement of highly oxygenated blood to the organs of the body. This has helped in thermal regulation and in rapid, sustained muscle movements.