Functions and Structure of Muscles
Energy Systems
ATP-PC system, Glycolytic system, Oxidative system.
Contractility
Ability of muscles to contract or shorten.
Elasticity
Ability of muscles to return to their original shape after contraction or extension.
Extensibility
Ability of muscles to stretch without being damaged.
Cross Bridge
Binding of myosin to actin, forming a bridge for muscle contraction.
Muscle Fatigue
Caused by ATP depletion, lactic acid accumulation, and electrolyte imbalances.
Sarcolemma
Cell membrane of a muscle fiber.
H Zone
Center of the A band containing only myosin filaments.
M Line
Center of the H zone, stabilizing the sarcomere.
Neurotransmitters
Chemicals released at the neuromuscular junction, initiating muscle contraction.
Perimysium
Connective tissue surrounding bundles of muscle fibers.
Endomysium
Connective tissue surrounding individual muscle fibers.
Ion Channels
Control the flow of ions necessary for muscle contraction.
Sarcoplasm
Cytoplasm of a muscle cell.
A Band
Dark bands containing both actin and myosin filaments.
Action Potential
Electrical signal generated in the muscle cell, leading to contraction.
Slow Twitch Fibers
Endurance-oriented muscle fibers.
T-tubules
Invaginations of the sarcolemma that transmit signals deep into the muscle fiber.
Smooth Muscle
Involuntary muscle found in internal organs, contracts slowly.
Cardiac Muscle
Involuntary muscle found in the heart, contracts rhythmically and is striated.
Calcium
Ion involved in muscle relaxation when removed from troponin.
I Band
Light bands containing only actin filaments.
Posture
Maintenance of body position and support of the skeleton.
Motor Unit
Motor neuron and the muscle fibers it innervates.
Skeletal Muscle
Muscle attached to bones responsible for voluntary movement.
Myocyte
Muscle cell containing sarcolemma (cell membrane) and sarcoplasm (cell cytoplasm).
Sliding Filament Model
Muscle contraction occurs as actin and myosin filaments slide past each other, shortening the sarcomere.
Fast Twitch Fibers
Muscle fibers suited for power and speed.
Cardiac Muscle
Muscle found in the heart, responsible for pumping blood, involuntary.
Smooth Muscle
Muscle found in the walls of internal organs, responsible for involuntary movements.
Heat Generation
Muscles produce heat during contraction, contributing to body temperature regulation.
Joint Stability
Muscles provide support and stability to joints.
Power Stroke
Myosin undergoes a power stroke, causing actin to slide.
Epimysium
Outer layer of connective tissue surrounding the entire muscle.
Neuromuscular Junction
Point of connection between a nerve ending and a muscle fiber.
Excitation-Contraction Coupling
Process by which muscle contraction is initiated.
Muscle Relaxation
Process of muscle returning to its original state after contraction.
Actin and Myosin Filaments
Protein filaments responsible for muscle contraction.
ATP
Provides energy for the cross-bridge cycle and muscle contraction.
Excitability
Responsiveness of muscles to stimuli, such as nerve signals.
Z Disk
Separates one sarcomere from the next, anchoring actin filaments.
Muscle tissue
Specialized tissue composed of muscle fibers that can contract.
Myoglobin
Stores oxygen in muscle cells for aerobic energy production.
Nerves and Blood Vessels
Supply muscles with nutrients and signals for contraction.
Movement
Voluntary and involuntary motions facilitated by muscles.