Muscles & Muscle Tissues - Part 2

These flashcards cover key concepts related to muscles and muscle tissues, focusing on the physiological processes, types of muscle contractions, and the roles of various proteins and ions in muscle function.

Action Potential

A rapid change in electrical charge that occurs across the sarcolemma of a muscle fiber, allowing for muscle contraction.

Depolarization

The process during the action potential when voltage-gated Na+ channels open, allowing Na+ to enter the cell and making the interior less negative.

Repolarization

The restoration of the resting membrane potential following depolarization, where K+ channels open and K+ exits the cell.

End Plate Potential

A local depolarization caused by the binding of acetylcholine (ACh) to receptors on the sarcolemma.

Excitation-Contraction Coupling

The sequence of events that transmits action potentials along the sarcolemma leading to the sliding of myofilaments.

Calcium Ions (Ca2+)

Essential ions released from the sarcoplasmic reticulum that bind to troponin to initiate muscle contraction.

Cross Bridge Cycle

The series of events where myosin heads attach to actin filaments and pull them towards the center of the sarcomere.

Motor Unit

A functional unit consisting of a motor neuron and all the muscle fibers it innervates.

Isotonic Contraction

A type of muscle contraction where muscle shortens and moves a load.

Isometric Contraction

A type of muscle contraction where muscle tension increases but the muscle does not shorten.

Muscle Twitch

The response of a motor unit to a single action potential of its motor neuron, characterized by a latent period, a period of contraction, and a period of relaxation.

Muscle Fatigue

The physiological inability of a muscle to contract even with continued stimulation, often due to ionic imbalances or lactic acid accumulation.

Muscle Mechanics

Principles governing muscle contraction, including muscle tension and load.

Fast Glycolytic Fibers

Muscle fibers that primarily use anaerobic glycolysis for energy, known for fast contraction speed but fatigue quickly.

Slow Oxidative Fibers

Muscle fibers that primarily use aerobic pathways for energy, known for slow contraction speed and fatigue resistance.

Wave Summation

The increase in muscle tension produced by gradually increasing frequency of stimulation.

Threshold Stimulus

The minimal strength required to generate an action potential in a muscle fiber.

Tropomyosin

A protein that blocks the binding sites on actin, preventing muscle contraction until calcium binds to troponin.

Troponin

A regulatory protein that binds calcium and causes tropomyosin to move away from actin binding sites, enabling muscle contraction.