Muscle Physiology: Contraction Mechanisms and Fiber Types

These flashcards cover key concepts related to muscle contraction mechanisms, types of muscle fibers, and physiological processes essential for understanding muscle function.

Cross Bridge Cycle

The process of myosin heads binding to actin filaments, leading to muscle contraction.

Sliding Filament Theory

Explanation of muscle contraction that states that muscle fibers shorten as thick myosin and thin actin filaments slide past each other.

Sarcromere

The basic functional unit of striated muscle fibers, defined by the section between two Z lines.

Tension

The amount of stretchiness a muscle experiences during contraction.

Load

The resistance or weight that a muscle must overcome during contraction.

Isotonic Contraction

A type of muscle contraction where the muscle changes length while the tension remains the same.

Isometric Contraction

A type of muscle contraction where the muscle length remains unchanged as tension increases.

Concentric Contraction

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

Eccentric Contraction

A type of isotonic contraction where the muscle lengthens while generating force.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber where the nerve impulse triggers muscle contraction.

Action Potential

A temporary change in membrane potential that induces muscle contraction.

Tetanic Contraction

A state of muscle contraction that occurs when muscle fibers are stimulated at a high frequency, resulting in a sustained contraction.

Fast Twitch Fibers

Muscle fibers that are adapted for rapid and powerful contractions using glycolytic (anaerobic) metabolism.

Slow Twitch Fibers

Muscle fibers that sustain longer, endurance-type contractions relying primarily on aerobic metabolism.

Muscle Fatigue

The decline in ability to generate force or power due to depletion of energy resources or accumulation of metabolic byproducts.

Calcium Ions in Muscle Contraction

Calcium ions bind to troponin on actin filaments to permit myosin heads to attach and initiate contraction.

ATP (Adenosine Triphosphate)

The energy currency of the cell, necessary for muscle contraction and relaxation.

Glycolysis

The metabolic pathway that converts glucose into pyruvate, producing ATP, particularly under anaerobic conditions.

Lactic Acid

A byproduct of anaerobic glycolysis that accumulates during intense exercise, contributing to muscle fatigue.