Muscles are engines, but they
are not heat engines in
the way an engineer would describe
one. A heat engine used heat and produces
heat.
Muscles are more sophisticated.
Manmade engines usually
burn fuel, such as gas,
petrol, or diesel. This produces a lot of heat and a comparatively
small amount of work. Muscles are more efficient. They oxidise a
specially made fuel which produces electrical energy and some heat.
MUSCLE EFFICIENCY is about 25%, which is about the same as a petrol car, but without reaching a high temperature.
MUSCLES start instantly, and
they adapt automatically to changing loads, and the run on fuel which
is made from a wide variety of different foods. No man-made machine has
ever been so adaptable and efficient.
Muscles run on
adenosine triphosphate.
Because of ATP and related reactions. a usefule amount of energy is always available for large or small bursts of activity.
There is a difference in appearance between
muscles which are used for short bursts of
activity, and long-term efforts. Short term
muscles are white - such as the wing muscles
of a chicken. Long term muscles are red, such as
the wing muscles of a pheasant or partridge.
Rabbit muscles are generally white (for the quick
dash to the burrow), but a hare's muscles are red,
because it lives in the open and has no burrow to run to.
