muscular 1

Three Muscle Types

Skeletal, Cardiac, and Smooth.

Skeletal Muscle

Striated, voluntary, multinucleated muscle attached to bones for movement, posture, stabilization, and heat generation.

Cardiac Muscle

Striated, involuntary muscle found only in the heart, contracts rhythmically.

Smooth Muscle

Non-striated, involuntary muscle that lines hollow organs, characterized by slow, sustained contractions.

Endomysium

Connective tissue that wraps individual muscle fibers.

Perimysium

Connective tissue that surrounds fascicles (fiber bundles).

Epimysium

Connective tissue that covers the entire muscle and blends into tendons or aponeuroses.

Sarcolemma

Plasma membrane of muscle fiber.

Myofibrils

Structures within muscle fibers that contain myofilaments (actin and myosin).

Sarcomere

Functional unit of muscle fiber, bounded by Z-discs.

I Band

Light zone of a sarcomere that contains only actin.

A Band

Dark zone of a sarcomere where actin and myosin overlap.

H Zone

Central region of the A band that contains only myosin.

M Line

Structure that anchors thick filaments in a sarcomere.

Sarcoplasmic Reticulum (SR)

Organelle that stores and releases calcium ions for muscle contraction.

Nerve Stimulus

Activation of muscle fibers through the release of acetylcholine at the neuromuscular junction.

Cross-Bridge Cycle

Process where myosin heads attach to actin to produce muscle contraction.

Relaxation

Process of detaching cross-bridges and returning calcium to the SR after contraction.

Direct Phosphorylation

Immediate energy source that converts creatine phosphate and ADP to ATP.

Aerobic Respiration

Metabolic process that occurs in mitochondria, producing 32 ATP per glucose with oxygen.

Anaerobic Glycolysis

Process that converts glucose to 2 ATP and lactic acid without oxygen.

Muscle Fatigue

Condition caused by ATP depletion, lactic acid buildup, and ion imbalances.

Isotonic Contraction

Muscle contraction type where muscle shortens while lifting weights.

Isometric Contraction

Muscle contraction type where muscle tension increases without shortening.

Twitch

Single, brief muscular contraction.

Summation/Tetanus

Sustained contraction resulting from rapid muscle stimulation.

Aerobic Exercise Effects

Improves endurance, metabolism, and fatigue resistance.

Resistance Training Effects

Leads to hypertrophy (muscle size increase) and improved strength.

Muscle Tone

Continuous partial contractions that maintain muscle readiness.

Immediate Energy Source

Energy for 0-15 seconds of activity, primarily from creatine phosphate.

Short-Term Energy Source

Energy derived from glycolysis, lasting 15-60 seconds, producing 2 ATP and lactic acid.

Long-Term Energy Source

Energy from aerobic respiration, providing 32 ATP from glucose for longer durations.

Atrophy

Prolonged inactivity results in muscle size and strength decrease.

Muscle strain

An injury where a muscle is stretched or torn.

Tendinitis

Inflammation of tendons due to overuse.

Muscle spasm

A sudden, involuntary muscle contraction.

Fibromyalgia

A chronic, widespread musculoskeletal pain and fatigue disorder.

Immediate Energy Source

Energy for 0-15 seconds of activity, primarily from creatine phosphate.

Short-Term Energy Source

Energy derived from glycolysis, lasting 15-60 seconds, producing 2 ATP and lactic acid.

Long-Term Energy Source

Energy from aerobic respiration, providing 32 ATP from glucose for longer durations.