Muscle Contraction, Twitch Physiology, and ATP Regeneration

These flashcards cover key terms and concepts related to muscle contraction, twitch physiology, and ATP regeneration discussed in the lecture.

Neuromuscular Junction (NMJ)

The site where a motor neuron communicates with a muscle fiber to stimulate contraction.

Acetylcholine (ACh)

A neurotransmitter released at the neuromuscular junction that binds to receptors on muscle fibers to trigger contraction.

Sarcoplasmic Reticulum (SR)

An organelle that stores Ca²⁺ ions and releases them to trigger muscle contraction.

Motor Unit

One motor neuron and all the muscle fibers it innervates.

Muscle Twitch

The mechanical response of a single motor unit to one action potential.

Latent Period

The time between stimulus and contraction start, during which action potential spreads and Ca²⁺ is released.

Contraction Period

The phase during which cross-bridges form, sarcomeres shorten, and muscle tension increases.

Relaxation Period

The phase during which Ca²⁺ is pumped back into the sarcoplasmic reticulum and the muscle returns to rest.

Isometric Contraction

A type of muscle contraction where tension develops without changing muscle length.

Concentric Contraction

A type of muscle contraction where the muscle shortens while generating force.

Direct Phosphorylation

A pathway for ATP regeneration where creatine phosphate donates a phosphate to ADP to form ATP.

Anaerobic Pathway

A method of ATP regeneration that uses glycolysis to produce ATP without oxygen.

Aerobic Pathway

A method of ATP regeneration that relies on cellular respiration in the mitochondria and requires oxygen.