Skeletal Muscle Anatomy & Physiology

These flashcards cover key vocabulary and concepts from the skeletal muscle anatomy and physiology lecture, aiding in study and retention for the upcoming exam.

Skeletal Muscle

Attached to bones, striated, voluntary, and powerful; constitutes ~40% of total body weight.

Smooth Muscle

Not striated, involuntary, found in the walls of hollow organs.

Cardiac Muscle

Striated, involuntary, and only found in the heart.

Epimysium

The outermost layer surrounding a muscle.

Perimysium

The layer surrounding each fascicle within a muscle.

Endomysium

The layer surrounding each muscle fibre (myofibre) within a fascicle.

Sarcoplasmic Reticulum

The structure that surrounds each myofibril, responsible for storing and regulating calcium.

Myosin

Thick myofilament that forms cross-bridges with actin during muscle contraction.

Actin

Thin myofilament containing binding sites for myosin, essential for muscle contraction.

Tropomyosin

Protein strand that helps stiffen and stabilize actin but blocks myosin binding sites.

Troponin Complex

Protein that attaches to tropomyosin and binds to calcium, facilitating muscle contraction.

Sarcomere

The repeating unit of fibres of actin and myosin that enables muscle contraction.

Motor Unit

Consists of a motor neuron plus the muscle fibres it innervates.

Action Potential

An electrical impulse produced by the motor neuron that causes muscle contraction.

Acetylcholine (ACh)

Neurotransmitter released by the motor neuron that binds to receptors on the sarcolemma.

Cross Bridge

The attachment of an energized myosin head to an actin binding site during contraction.

Sliding Filament Theory

Explains muscle contraction based on the sliding of actin and myosin past each other.

Isotonic Contraction

Muscle contraction with a change in length.

Isometric Contraction

Muscle contraction without a change in length.

Eccentric Contraction

Type of contraction where the muscle lengthens.

Concentric Contraction

Type of contraction where the muscle shortens.

Pre-Stretching

Technique wherein muscles perform more work when concentrically contracting after being stretched.

Force-Time Relationship

The principle that force generated by a muscle is proportional to contraction time.

Fiber Types

Muscle fibers categorized into Type I (slow twitch), Type IIa (fast oxidative), and Type IIb (fast glycolytic) based on speed and metabolic properties.

Musculotendinous Unit (MTU)

Structure composed of skeletal muscle, tendons, and connective tissue.

Electromyography (EMG)

Technique used to study electrical activity in muscles through electrodes.

Calcium's Role in Contraction

Essential for exposing binding sites on actin by affecting troponin and tropomyosin.

Temperature Effect on Muscles

Higher temperatures improve stimulation frequency, enzyme activity, and collagen elasticity.

Remodeling

The process where muscle adapts through atrophy or hypertrophy based on usage or disuse.