EMG (human skeletal muscle functions)

Question 1

Motor unit

Answer 1

a single somatic motor neuron + all innervated skeletal muscle fibers. Precise movement: small motor unit size. Large-scale, powerful movement: large motor unit size.

Question 2

Muscle tone

Answer 2

the maintenance of partial contraction of a muscle, important for maintaining posture and balance, and controlling proper function of other organ systems

Question 3

Motor unit recruitment

Answer 3

number of active motor neurons is increased. Smallest/weakest motor units are activated first, followed by larger motor units

Question 4

Muscle fatigue

Answer 4

inability of muscle to maintain force of contraction

Question 5

Dynamometer

Answer 5

measurement of the power of muscle contraction (clench force)

Question 6

Electromyography

Answer 6

measurement of the sum of electrical impulses provided by the activated muscle fibers during muscle contraction

Question 7

Size principle

Answer 7

states that as more force is needed, motor units are recruited in a precise order according to the magnitude of their force output, with small units being recruited first. 2 benefits: minimizes the amount of fatigue + permits fine control

Question 8

Differentiation between less and well trained muscles

Answer 8

Well-trained muscles have more myofilaments per muscle fibers, and does therefore not leave to recruit as many motor units as an unfit person to generate the same amount of force.