Muscle Types and Mechanisms

These flashcards cover key vocabulary related to muscle types, mechanisms of contraction, and muscle energetics.

Skeletal Muscle

Voluntary, striated, multinucleated muscle organized into sarcomeres.

Cardiac Muscle

Striated, involuntary muscle connected by intercalated discs and electrically coupled.

Smooth Muscle

Non-striated, involuntary muscle using different regulatory mechanisms such as calmodulin.

Myofibrils

Structures composed of repeating sarcomeres, containing thick (myosin) and thin (actin, tropomyosin, troponin) filaments.

Striations

Visible bands in skeletal and cardiac muscle due to alignment of sarcomeres.

The Sliding Filament Theory

Mechanism of muscle contraction where myosin binds to actin, resulting in sarcomere shortening.

Excitation–Contraction Coupling (ECC)

Process by which an action potential triggers muscle contraction through calcium ion release.

Calmodulin

Protein that binds calcium ions and activates myosin light chain kinase (MLCK) in smooth muscle.

Force-Velocity Relationship

Describes how muscle shortening velocities decrease with increasing load.

Phosphagen System

Immediate source of ATP in muscles using creatine phosphate.

Fatigue Mechanisms

Processes such as metabolic depletion, accumulation of Pi, and central fatigue that contribute to muscle failure.

Latch State

Phenomenon in smooth muscle allowing sustained contraction with low ATP consumption.

Frank–Starling Mechanism

Concept where increased filling of the heart results in increased contractile force.

Pacemaker Cells

Specialized heart cells responsible for the rhythmic contraction through spontaneous depolarization.

Isometric Contraction

Muscle contraction where tension increases but length remains constant.

Isotonic Contraction

Muscle contraction where tension remains constant while muscle length changes.