MOVEMENT ANALYSIS

What is a motor unit?

A motor unit is the smallest functional unit of the nervous system, comprising a single motor neuron and all the muscle fibers it innervates.

Why is a motor unit considered the final output of motor commands?

The activation of a motor unit directly leads to muscle contraction.

What role does acetylcholine play in muscle contraction?

Acetylcholine is a neurotransmitter that triggers muscle fiber depolarization and initiates contraction.

What is the function of cholinesterase?

Cholinesterase breaks down acetylcholine, allowing the neuron to repolarize and the muscle to relax.

Outline the sliding filament theory in three steps.

1. Calcium binds to troponin, moving tropomyosin to expose actin-binding sites; 2) Myosin heads bind to actin, forming cross-bridges; 3) ATP binds to myosin, breaking the cross-bridge, allowing the cycle to repeat.

What are the key differences between slow-twitch and fast-twitch muscle fibers?

Slow-twitch fibers are fatigue-resistant and aerobic, while fast-twitch fibers generate more power but fatigue quickly and are anaerobic.

Give an example of a synovial joint.

A ball-and-socket joint, such as the hip, which allows movement in multiple planes.

What is a concentric contraction?

A muscle contraction in which the muscle shortens while generating force.

What is an eccentric contraction?

A muscle contraction in which the muscle lengthens while generating force.

Explain the concept of reciprocal inhibition.

Reciprocal inhibition is the relaxation of antagonist muscles to allow agonist muscles to contract efficiently.

Differentiate between scalar and vector quantities.

A scalar quantity has magnitude only (e.g., mass), while a vector quantity has both magnitude and direction (e.g., force).

How does the position of the center of mass affect stability?

A lower center of mass increases stability; if the center of mass falls outside the base of support, stability is compromised.

What are the three classes of levers?

1st class: fulcrum between effort and load; 2nd class: load between fulcrum and effort; 3rd class: effort between fulcrum and load.

What is acetylcholine?

A neurotransmitter responsible for initiating muscle contraction at the neuromuscular junction.

What is actin?

A thin protein filament that interacts with myosin to cause muscle contraction.

What is an agonist muscle?

The muscle primarily responsible for producing a specific movement.

What is an antagonist muscle?

The muscle that opposes the action of the agonist muscle.

What is an axon?

A long projection of a nerve cell that conducts electrical impulses away from the neuron's cell body.

What is the center of mass?

The point where mass is evenly distributed; it is critical for determining stability.

What is cholinesterase?

An enzyme that breaks down acetylcholine.

What is the sliding filament theory?

The explanation of muscle contraction involving the sliding of actin filaments past myosin filaments.

What is torque?

A twisting force that tends to cause rotation.

What is a vector?

A quantity that has both magnitude and direction.