Re: does holding your breath effect your heart rate? if it does how?

The heart and respiratory system work actually separately. However when 
one holds his breath there is a negative suction pressure in the thorax 
that tends to pull open the organs or inflate them. Due to this the heart 
tends to take more time in filling and so it fills more and pumps more 
blood but its rate of pumping decreases due to longer filling periods.

Now about the brain, if your brain does not get oxygen for about 3-4 min 
it will start dying. But you cant hold your breath for long by yourself 
because when the brain comes in high stress it pushes you automatically to 
breathe.