how does blood get to the heart from the lower extremities if it has to fight gravity?
2006-11-28 01:50:50 · 5 answers · asked by jamz 5 in Health ➔ Diseases & Conditions ➔ Heart Diseases
Good answers so far but the way blood actually fights gravity from the lower parts of the body up to the heart is through a very simple "step ladder" mechanism. The blood is pumped up a small ways and past a valve that the pressure of the blood falling back against after the pressure of the pump subsides actually closes. The blood sits there for a second waiting for the next heart beat that forces more blood up to and then opening that same valve past which more blood is pushed...and the whole thing repeats over and over....in this manner the valves in the veins provide footholds for the blood as it climbs its way up to the heart. Check the site below for a more formal explanation and post an added question if you are interested in some good heart model websites...Take Care!
I found the picture I was looking for on my old physiology cd. At the link below you notice the valve at top left opening with the flow of blood then on thew top right closing as the blood flows back creating the "foothold" on the "step ladder" mechanism that allows the blood to move UP towards the heart and AGAINST gravity.
http://img221.imageshack.us/img221/8952/0709lmx6.gif
2006-11-28 12:29:38 · answer #1 · answered by smithwss 2 · 1⤊ 0⤋
Blood is actively pumped through the arteries so there is always a forward 'pressure'. Veins have valves which prevent blood from going 'backwards'. Thus the forward pressure from the arteries pushes blood past several valves with each heartbeat and eventually blood completes its circuit to the heart. The number of heart beats required to return blood to the heart varies from person to person and from healthy people as opposed to those with heart disease. Circulation of blood was generally appreciated even in the oldest medical writings extant.
2006-11-28 02:41:09 · answer #2 · answered by john e russo md facm faafp 7 · 2⤊ 0⤋
Each time the left ventricle contracts the pressure pushes the blood through the circulatory system. Blood is being circulated by valves opening and closing in the heart. So opening valves allow blood flow in in making room for the ventricle to push foward. Try this link to help u visualize
http://health.allrefer.com/health/aging-changes-in-the-heart-and-blood-vessels-circulation-of-blood-through-the-heart.html
2006-11-28 02:01:00 · answer #3 · answered by rodeorn62 2 · 1⤊ 0⤋
The human heart is a powerful muscle that can pump blood to all corners of the body, thereby overcoming gravity.
2006-11-28 01:59:13 · answer #4 · answered by Ebones 2 · 0⤊ 1⤋
The calf musle pumps work overtime, venous unidirectional valves prevent flow back.
2006-11-28 02:03:49 · answer #5 · answered by drthram 1 · 1⤊ 0⤋