Question

An alpha (a) motor neuron & all of the skeletal muscle fibers that it innervates is defined as a motor unit.

a) True
b) False

Answer 1

The statement is true; a motor unit consists of an alpha motor neuron and all the skeletal muscle fibers innervated by it, varying in size to facilitate different types of muscle control.

Step-by-step explanation:

That statement is true. A motor unit comprises an alpha motor neuron and all of the skeletal muscle fibers it innervates. Muscle fibers are each innervated by only one motor neuron, and together, they participate in muscle contraction. The size of a motor unit varies depending on the muscle's function. Large motor units control gross movements and typically innervate more muscle fibers, making them common in muscles like the quadriceps. On the other hand, small motor units provide fine motor control with fewer muscle fibers per motor neuron, such as those in the extraocular muscles controlling eyeball movement.

Answer 2

The statement that an alpha (a) motor neuron and all of the skeletal muscle fibers it innervates defines a motor unit is True. Motor unit sizes vary based on muscle function, with smaller units providing fine control and larger units governing gross movements.

Step-by-step explanation:

An alpha (alpha (a) motor neuron) & all of the skeletal muscle fibers that it innervates is defined as a motor unit. The statement is True. A motor unit encompasses the singular motor neuron and the host of skeletal muscle fibers it innervates. Each muscle fiber is controlled by only one alpha motor neuron, and the size of a motor unit can vary greatly depending on the muscle's function.

Motor units are different in size; for precise, fine motor control, there are typically smaller motor units, such as the motor units found in the muscles controlling the eyes, which only control a few muscle fibers each. Conversely, motor units that govern gross movements, like those in the thigh muscles, may control thousands of muscle fibers, providing less precise control but more power.