Neuromuscular Function

Disclaimer – Mrs. Rowe did NOT create this – but I am sharing it.

Movement Analysis

Neuromuscular Function:I. The Motor Unit:

II. The Structure of Muscle Tissue:

III. The Role of Neurotransmitters in stimulating skeletal muscle contraction:

A. Acetylcholine (Ach): increases the post-synaptic membrane’s permeability to sodium and potassium ions spreading the impulse over the entire muscle fiber.

B. Cholinesterase: enzyme that breaks down Ach repolarizing the muscle fiber to await another nerve impulse.

IV. Skeletal Muscle Contraction:

A. The sliding filament theory:

Steps of a muscle contraction:

*Ca++ are released by the sarcoplasmic reticulum.

*Ca++ binds to troponin preventing the blocking action of tropomyosin.

Sliding filament cont.

*myosin heads can now attach to active sites on the actin filament.

*myosin heads pulls on the actin filament, decreasing the width of the sarcomere.

*myosin head releases the actin when a new ATP is formed.

V. Types of Muscle Fibers:

A. Slow Twitch: (type 1)*smaller in diameter*reddish color*use aerobic resp. for ATP

supply*contain more mitochondria*fire slowly, but take long to

fatigue.

B. Fast Twitch: used for short explosive movements, stop and go sports.

Type IIA:*large diameter*white in color*less mitochondria*uses both anaerobic and

aerobic energy transfer

Type IIB: *same physical

characteristics as Type IIA, but strictly uses the glycolytic anaerobic system.