MPharm-ATT-Y1-2024-MH-Skeletal-Muscle-Phys

Skeletal Muscle

Most abundant muscle in the body, connected to bones to facilitate movement. striated muscle

Smooth Muscle

Muscle found throughout the body, lining organs such as blood vessels and intestines; controls movement of organ contents. Unsriated muscle

Cardiac Muscle

Muscle found in the heart; responsible for pumping blood throughout the body. Sriated muscle

Isometric Contraction

Muscle contraction where tension is developed without shortening, e.g., holding a book static.

Isotonic Contraction

Muscle contraction where the muscle shortens under constant load, e.g., picking up a book.

Myofibril

Specialized intracellular structure within muscle fibers, composed of hundreds to thousands of sarcomeres.

Sarcomere

The contractile unit of skeletal muscle, bordered by Z-lines. It consists of alternating I bands (light bands containing thin filaments) and A bands (dark bands containing thick filaments), allowing for the sliding mechanism of contraction.

Titin

Large protein that provides structural support to the sarcomere, known for its spring-like structure.

Cross Bridge

Points of contact between thick (myosin) and thin (actin) filaments during muscle contraction.

Sliding Filament Theory

Theory explaining muscle contraction through the sliding of actin and myosin filaments past each other.

Action Potential

Rapid depolarization of the cell membrane that triggers muscle contraction.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber where neurotransmitter release occurs.

Acetylcholine (ACh)

Neurotransmitter released at the neuromuscular junction to initiate muscle contraction.

Excitation-Contraction Coupling

Process where an action potential leads to muscle contraction through Ca2+ release.

Muscle Fatigue

A state where a muscle can no longer respond effectively due to energy depletion or lactic acid accumulation.

Type I Muscle Fibers

Slow-oxidative fibers characterized by small diameter and high resistance to fatigue.

Type IIa Muscle Fibers

Fast-oxidative fibers with intermediate diameter and fast contraction speed.

Type IIb Muscle Fibers

Fast-glycolytic fibers that generate ATP anaerobically and are characterized by large diameter.

Creatine Phosphate (CP)

An immediate energy source for muscle contraction, with resting levels 5 times that of ATP.

Rigor Mortis

Stiffening of muscles post-mortem due to ATP depletion, preventing detachment of actin and myosin.

Motor Unit

The functional unit of skeletal muscle comprising a motor neuron and the muscle fibers it innervates.

Calcium ATPase

An enzyme that uses ATP to transport calcium ions back into the sarcoplasmic reticulum, crucial for muscle relaxation.