The minimum stimulus needed to cause a contraction is called the:
1. chronaxie
2. threshold
3. rheobase
4. reversal potential

A sustained muscle contraction evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate is called as:
1. a sustained contraction
2. fatigue
3. tetanic contraction
4. treppe

The continuous and passive partial contraction of the muscles is called as:
1. tetany
2. tonus
3. sustained contraction
4. summation

Stimulation by a nerve impulse is always required for the contraction of:
1. multi-unit smooth muscle
2. skeletal muscle
3. visceral smooth muscle
4. cardiac muscle

A decrease in the mass of the muscle most commonly experienced when persons suffer temporary disabling circumstances is called as:

1. hypertrophy

2. atrophy

3. dystrophy

4. peristalsis

A neuromuscular disorder that causes weakness in the skeletal muscles is:

Immediately after the motor neuron passes an impulse to a muscle fiber:
1. the impulse travels over the sarcolemma in all directions.
2. calcium is released from the sarcoplasmic reticulum.
3. cross bridge forms between the actin and myosin.
4. troponin undergoes a conformational change.

Identify the incorrect statement:
1. A muscle fiber contracts in an all-or-none fashion.
2. A slight delay occurs between the reaching of impulse at the neuromuscular junction and muscle contraction.
3. Using more motor units will increase the overall force of contraction.
4. When a person is fully at rest, none of her muscles are contracting.

Identify the incorrect statement regarding a skeletal muscle fiber:
1. They continue to divide throughout childhood as skeletal muscles grow
2. Theyare formed by fusion of myoblasts during fetal development
3. They are true syncytium.
4. They are striated.

What happens during the contraction of a skeletal muscle fiber?