I found this awesome article that seems to explain a lot about what goes on with us.

http://www.kclj.si/ikn/DEJA/Continuu...htoMGorALS.pdf

(Pages 4-5)
Respiratory muscles. It is frequently
difficult to reliably distinguish the
status of the respiratory muscles
from the functional status of the lungs
themselves. However, simple observation
is often quite revealing. Patients
with respiratory muscle weakness due
to MG often present with tachypnea
and shallow breathing. They may be
anxious because of an inability to draw
a full breath. Asking patients to inspire
forcefully and loudly through the
nose (inspiratory sniff) can give one a
good indication of inspiratory muscle
strength. To assess expiratory muscle
function, patients should be asked to
cough or clear their throat. Outward
protrusion of the abdomen against
the examiner’s hand is an indirect
measure of diaphragmatic strength
since the abdominal contents will be
pushed upward instead of outward if
the diaphragm is weak. A weak sniff
and cough along with significant
tachypnea or tachycardia
are signs of clinically important respiratory
muscle weakness.

So, that sort of explains why our hearts beat so FAST sometimes, huh??