Graded Muscle Contractions

Question

Graded muscle contractions .
A) depend on increasing frequency of nerve action potentials to each motor unit
B) represent increasing amounts of force generated by a muscle
C) depend on activation of more and more motor units
D) all of the above

Accepted Answer

Graded muscle contractions involve all of the mentioned mechanisms: increasing the frequency of nerve action potentials (which can lead to summation and tetanus), generating more force as more motor units are activated (recruitment), and indeed, the overall process depends on both the frequency of stimulation and the number of motor units activated.