Not sure if this is the correct forum. The universe is a closed system as in energy is a constant. Is the same true of the heart? Also, if the heart is a closed system, does the energy within the heart transform? Just playing with an idea, any thoughts appreciated.
The heart is not a closed system. If no outside energy is supplied to the heart it will cease to function. No outside energy supply to your heart would result in a bad day for you.
my analysis: the heart relies on nutrients to continue living. these nutrients can only be supplied from outside the body. no the heart is not a closed system. OTOH, the body itself can be considered a closed system if we make a few assumptions. for example: there is such a thing called the "blood/brain" barrier that certain molecules can't breach. the brain in this instance can be considered closed to these molecules. in my opinion: a truly closed system implies some kind of "perpetual motion machine". we all know the story about that . . .
You'll have to be more specific of what the definition of "closed system", and as an extension - it's relativity. In biology, there are two types of circulatory systems. An open circulatory system is where a tubular shaped heart pumps blood through sinuses throughout the organism - with sparce and non significant blood vessels occasionally existing throughout. These open systems are observed amongst all Arthropoda. A closed circulatory system is when blood is pumped from the heart into circulatory blood vessels that carry it to distinctive locations. The real difference in closed circulation is that blood never leaves the circulatory pathways. In this way, yes the heart is by definition a Closed circulatory system. If you mean to say that the heart requires no dependency on outside energy (which seems to be the case) it should be immediately obvious that the opposite is true. Our bodies rely almost exclusively off of the process of ATP synthesis. The heart is then no different than any other organ in its energy dependency. I would love to hear the reasoning behind alternative input, if anyone has some.
Excellent post, touching on exactly what I'm asking. I read an article that suggested that the heart(forget vascular side of things) is made up of energy that doesn't change. I cannot find the article that explains my question as I read it on a different computer and have no history of it. It was a scientific article though.
I think something must have got lost in your understanding of the article, if indeed it was written by someone sensible. As several contributors have pointed out, the heart is a muscular organ that needs an energy supply. This is because the heart does mechanical work, by pumping the blood through the body against the resistance to flow that the blood vessels impose. Work is a form of energy, so something that does work needs to get energy from somewhere, to turn it into work. In the case of the heart, the energy comes from the blood, as it does for all other organs of the body. The blood supplies the fuel (glucose etc) and the oxygen to enable the cellular respiration reactions to occur: http://en.wikipedia.org/wiki/Cellular_respiration This is clearly an open process, since the oxygen in the blood comes from the lungs, while the fuel in the blood comes from the digestive system. When part of the heart muscle is deprived of its blood supply, it stops working - and a heart attack ensues. So this thing about the heart being "made up of energy that doesn't change" can't be right.
Did you mean to say it's relative? "Closed system" here refers to a thermodynamic system enclosed by a boundary. If there is a net transfer of matter and energy across the boundary then we say the system is not closed. Also the readers should be made aware of the evolutionary significance of this. Arthropoda preceded Insecta - the largest class on Earth, so the difference in heart and circulation, as opposed to vertebrates - splits approximately between Arthropoda and Planaria. Also note the closed circulatory system is not completely closed. Bilorubin, for example, is an intermediate substance which can be either used in building new red blood cells, or in producing bile, necessary for digestion. When dead hemocytes yield bile, which is then lost through excretion, the system can be called "partly closed". A good exercise for biology fans is to investigate the range of bilorubin lost in normal people with a balanced diet, vs those with an iron poor diet. And in the process, we discover a system that aids in the survival of a population based on alternating seasons of feast and famine. Also for further discussion is the evolution of blood itself, and the various forms in different organisms. Related is the question of blood mutations seen in humans, and the implications for survival in the pressure of the niche: blood types, Rh factor, and the mutation for Sickle Cell come to mind. This may be the source of confusion that Dave started with. I would just add that there is another closed loop associated with the heart, and that is the nervous system. Here it branches into specialized neurons which sense the contractions, add delay, and then trigger the next cycle autonomically. This system is not thermodynamically closed either, of course. But it speaks volumes to the evolutionary history of organisms.
I'm asking if the heart is a closed system, which means the energy it contains is constant, it doesn't require additional energy. The heart is inside your body, or let's say a dogs body. Blood pumps through the heart, but the heart itself is a pump, which can give up if you have a heart attack, or if too much blood is lost and the pressure drops. If you can imagine a bicycle pump, that pumps air into an inner tube. If there is smoke in the air then it will pump some smoke into the inner tube, however the pump remains unchanged, but obviously degrades over time. Second law of thermodynamics. EDIT: Added - degrades over time. Second law of thermodynamics.
So now you understand that the answer is no, that is, the oxygen and nutrients consumed by the heart pass as matter across the system boundary, where they are converted to energy during heart cell metabolism. Dead cells and waste products of metabolism pass out across the system boundary. Low pressure (low energy) blood enters and high energy (pressurized) blood exits (although the 4 chamber system needs fuller explanatory detail). Therefore if you draw a boundary around the heart, and call the enclosed region a thermodynamic system, then you have a lot more work to do to resolve the energy budget, since this is not a closed system. But make no mistake: all living cells, tissues, organs and organisms do not - and cannot - act as closed thermodynamic systems. For the same reason, the "reversal of entropy" argument used by Creationists -- in regard to any cell, tissue, organ or organism -- is false and incorrect.
Does a bicycle pump change? You are still talking about the vascular element, and I'm not sure why you mentioned "Creationist", why did you mention them?
Not sure what you mean by that. Change what? Not sure what you mean by this either. To clarify the meaning of a "closed system": the Second Law of Thermodynamics states that there is a net energy loss (gain in entropy) when measured at the system boundary. The boundary is any surface which isolates the system from its surroundings. A thermodynamic system is further defined as one which is "closed", which means that there is no net exchange of matter and/or energy across that boundary. This is pretty straightforward for machines, but it is incorrect to compare living cells, tissues, organs or organisms to machines in this regard. That is, they will only remain alive through the consumption of oxygen (or other gases) and nutrients brought across the system boundary. That transfer of gases and nutrients into the boundary, and the excretion of waste products out of the boundary, will always result in a net loss of matter. That net loss invalidates the modelling of the cell, tissue, organ or organism as a closed system. Therefore, the Second Law of Thermodynamics is not, and can not be, applicable to living matter. Because Creationism (Intelligent Design) claims that the Creation of life on Earth could not occur without God's repeal of the laws of nature, since it constitutes a reversal of entropy in violation of the Second Law of Thermodynamics. Ignoring the absurdity of claiming that this leads to the inference that God created life, the fatal flaw to this argument is that it ignores the issue you have raised here: namely, the Second Law only applies to closed systems. Since cells, tissues, organs and organisms are not, and can not be, closed systems, then the Second Law does not apply to them, therefore the Creationists are wrong. In fact this is a prime example of using pseudoscience as a pretense for shoring up religious claims. The whole purpose of the Creation Science movement is to replace science with pseudoscience in order to deceive gullible followers into believing there is a scientific basis for the adopting the literal interpretation of their Creation Myth. My rationale for addressing it here is to help readers understand why the Creationist argument is invalid and incorrect.
This is a fairly nice explanation. It really touches all of the bases that I can think of. I might show some of my colleagues this.
