EFFECT OF TEMPERATURE ::
When the temperature around the muscle is increased following changes occur in the muscle .
1. chemical processes involved in contraction and relaxation are hurried up.
2. viscosity of the muscle is diminished
3. there is increase in excitability
4. height of contraction increases because the speed of contraction increases and this is because the viscosity is diminished in this way it is really a mechanical effect warm saline decreases the viscosity of muscle and hence the muscle contracts quickly and this leads to increase in the height of contraction
if the temperature is too low (below 5.c ) the conduction velocity of nerve impulse is nearly abolished and so contraction may not be observed if the temperature is too high (above 40.c or 45.c ) muscle undergoes a sustained contraction which is irreversible this is known as heat rigor it is identical to rigor mortis in both cases::
(1) muscle proteins are coagulated
(2) muscle becomes opaque firm and stiff
(3) muscle contracts for longer time and to a greater extent
(4) irritability is lost in both these conditions muscle will not contract even if a very strong stimulus is given
0 Comments