Muscular System

Muscular system

Made up of muscles that allow the body to move, maintaining posture, stabilizing joints, producing heat, and helping perform physical activities.

Types of muscle

The three main types are: skeletal, cardiac, and smooth muscle.

Skeletal muscle

Voluntary muscle responsible for moving the skeleton, striated appearance, and controlled consciously.

Cardiac muscle

Involuntary muscle found only in the heart, it is striated and contracts to pump blood continuously.

Smooth muscle

Involuntary muscle found in internal organ walls that helps move substances through the body.

Agonist

The main muscle responsible for producing a movement.

Antagonist

The muscle that produces the opposite movement of the agonist, relaxing while the agonist contracts.

Synergist

A muscle that assists the agonist in producing movement.

Fixator

A muscle that stabilizes a body part while another muscle produces movement.

Isometric contraction

Muscle produces tension without changing length, with no joint movement.

Concentric contraction

Muscle shortens while producing force, causing movement.

Eccentric contraction

Muscle lengthens while producing force, often controlling or slowing a movement.

Type I muscle fibres

Slow-twitch fibres suited for endurance, resistant to fatigue.

Type IIa muscle fibres

Fast oxidative fibres with characteristics of both endurance and power.

Type IIx muscle fibres

Fast-twitch fibres suited for short, powerful activities, fatiguing quickly.

Muscle fatigue

Reduced ability of a muscle to continue producing required force.

Motor unit

One motor neurone and all the muscle fibres it controls.

Tendon

Connects muscle to bone.

Actin

Thin protein filament involved in muscle contraction.

Myosin

Thick protein filament involved in muscle contraction.

Sliding filament theory

Explains how skeletal muscles contract through the interaction of actin and myosin.