*Week 1: Skeletal Muscle Structure and Function and Lever Systems

Skeletal Muscle

A contractile organ usually attached to bones by tendons, responsible for movement and thermoregulation.

Actin

A contractile protein that forms thin filaments and interacts with myosin to facilitate muscle contraction.

Myosin

A contractile protein that forms thick filaments and interacts with actin to facilitate muscle contraction.

Sliding Filament Theory

The theory explaining muscle contraction by the sliding of actin over myosin, shortening the sarcomere.

Neuromuscular Junction (NMJ)

The synapse where the motor neuron communicates with the muscle fiber, initiating muscle contraction.

Cross-Bridge Cycle

The process of actin and myosin binding, pivoting, and detaching that enables muscle contraction.

Tetanus

A sustained muscle contraction resulting from high-frequency stimuli.

Isotonic Contraction

A muscle contraction that results in a change in muscle length without changing tension.

Isometric Contraction

A muscle contraction that does not result in a change in muscle length while generating tension.

Motor Unit

A motor neuron and all the muscle fibers it innervates, working together as a functional unit.

Adenosine Triphosphate (ATP)

The primary energy carrier in cells, required for muscle contractions and other cellular processes.

Creatine Phosphate

A molecule that assists in converting ADP back to ATP during short bursts of high energy.

Aerobic Respiration

The process of producing ATP with the use of oxygen, resulting in a high yield of ATP.

Anaerobic Glycolysis

The conversion of glucose to ATP in the absence of oxygen, yielding a lower amount of energy rapidly.

Frank-Starling Law

Principle that states muscle tension increases with an optimal degree of stretch before contraction.

Fulcrum

The fixed pivot point around which a lever rotates, crucial for understanding lever systems in muscle mechanics.

Excitation-Contraction Coupling

The process linking the action potential generated at the NMJ to muscle contraction.

T Tubules

Transverse tubules that allow action potentials to penetrate deep into the muscle fiber.

Sarcoplasmic Reticulum

The specialized endoplasmic reticulum in muscle fibers, responsible for storing and releasing calcium ions.

Muscle Fatigue

The inability of a muscle to maintain a contraction, typically due to prolonged activity or energy depletion.