How much can people control their organs?

Question

Can people show down or speed up their heart rate? Can you deny or increase oxygen to your own brain?

Answer 1

saz17 is right...we can control our respiration (ventilation) voluntarily to a certain level. you can try and hold your breath but not indefinitely because you will eventually surrender and breathe. this is not because you don't have enough oxigen left in your lungs (or blood), there's plenty of oxigen in the blood that can keep your body alive for 4 to 5 more minutes (in case your heart stopped or you fell unconscious). but it is the increased concentration of CO2 that triggers breathing...you see the levels of CO2 increase significantly if you try to hold your breath for a long time, and this will make your blood more acidic (PH of the blood decreases below 7). So the nervous system (particularly the autonomous nervous system which is the medulla oblongata) will force you to breath to restore the blood PH to 7.

as for the heart rate, it can be controlled partially by the nervous system. for example, some singers or performers have stage fright and this causes their heart rate to increase because of adrenaline secretion. however, other singers are used to sing on stages and thus they don't have fright stage and have normal heart rate. another example is when you want to fight, you feel your heart rate increasing...this is because the autonomous nervous system (sympathetic) is secreting adrenaline which causes these effects...

i hope that helped....good luck (don't get into fights :P)

Answer 2

Some people have the extraordinary ability to be able to exert some voluntary control over autonomic nerves and can control their heart rate a little bit.  We can all hold our breath and prevent proper ventilation which will affect the oxygen levels in the blood, but our autonomic nervous system will over-ride this as increased levels of carbon dioxide are detected and we will breathe.  Very often, young children in a temper tantrum will hold their breath until they are almost blue and then collapse.  At this point they will breathe although understandably it is traumatic for the poor parent!