Circle of Willis

The Circle of Willis is the spot where blood is brought to the brain to be distributed to the different lobes. It is made up of the Right and Left posterior communicating arteries and the anterior communicating artery. Blood is brought up from 2 different paths to make a anatomical redundancy. Blood flows from the left ventricle to the aortic arch then splits right into the Brachiocephalic artery then to the right common carotid, then to the right internal carotid artery to the Circle of Willis. This happens on the left side as well but there is no Brachiocephalic artery. It also receives blood from the left and right Subclavian to the right and left Vertebreal artery then join at the Basilar then up to the Circle of Willis. This system helps assure that if there is a problem with blood flow from one source there is still a chance for blood to make it to the brain because after about 4 minutes of no oxygen to the brain, cells start to die and permanent brain damage can occur. Here is a web site with a picture to see more clearly en.wikipedia.org/wiki/Circle_of_Willis

This happens all the time in all of us and helps ensure plenty of oxygen make it to the brain which is the most important organ in our bodies. Though i guess with modern technology you can still live with machines causing you to breath and circulate blood. I'm not sure if that would still be considered living or not and since the case of the Schiavo's where she was in a comatose state for 13 years and they decided to pull the plug and allow here to die that maybe it wouldn't be considered living. In this case the courts and even the congress got involved with the decision where the husband won and the parents lost. My personal opinion is the parents couldn't let go of there child (which i can understand somewhat) but after a certain amount of time i think its time to let go. Someday she may have been able to be revived if medicine gets to that point but to my knowledge they aren't that close so who knows how long it would be before this could happen.