Neuromuscular system

Cardiac Muscle

Type of muscle that contains a single nucleus, is cylindrical and branched.

Skeletal Muscle

Type of muscle that takes 40% of body weight, is voluntary, and contains multiple nuclei.

Smooth Muscle

Involuntary muscle that is widely distributed, mostly found in organs, and contains a single nucleus.

Autorhythmic

Refers to cardiac and smooth muscles that can generate their own rhythm.

Contractility

The ability of muscles to contract.

Excitability

The ability of muscles to respond to electrical stimuli.

Extensibility

The ability of muscles to stretch beyond their normal length.

Elasticity

The ability of muscles to return to their resting length.

Epimysium

The connective tissue that covers the whole muscle.

Perimysium

The connective tissue that divides muscles into bundles of muscle fibers called fascicles.

Endomysium

The connective tissue that provides pathways for vessels and nerves within muscles.

Motor Neuron

Neurons that extend from the brain and spine to muscles via nerves.

Myoblasts

Cells that create muscle tissue.

Sarcomere

The smallest contractile unit of muscle, made of myosin and actin myofilaments.

Myofibrils

Structures within muscle fibers formed by joining sarcomeres end-to-end.

Titin

The largest protein in the human body that allows muscles to stretch and recoil.

Ca2+ Release

The trigger for muscle contraction.

Motor-end Plate

The specialized region of the muscle fiber membrane at the neuromuscular junction.

Myosin Myofilaments

Thick filaments in muscle that bind to actin and contain ATPase enzymes.

Hypertrophy

The increase in the size of muscle cells, leading to greater muscle mass without an increase in number.

Electrical Component

Refers to electrical signals that stimulate muscle contraction and growth.

Mechanical Component

Involves physical forces and tension applied to muscles during resistance training.

Sarcolemma

The plasma membrane surrounding a muscle fiber.

Transverse Tubules

Extensions of the sarcolemma that penetrate into the muscle fiber.

Myofilaments

Filaments of myofibrils composed of actin and myosin.

L-band

The light band in a sarcomere, primarily composed of actin.

A-band

The dark band in a sarcomere containing both actin and myosin.

M-lines

The middle line of a sarcomere that anchors myosin filaments.

H-zone

The lighter region in the A-band where only myosin is present.

Z-disk

The boundary structure of a sarcomere that anchors actin filaments.

G Actin

The monomeric form of actin.

F Actin

The polymer of G actin that forms thin filaments.

Synaptic Cleft

The gap between the axon terminal and the muscle fiber at a neuromuscular junction.

Acetylcholine

A neurotransmitter that transmits signals from motor neurons to muscle fibers.

Acetylcholinesterase

An enzyme that breaks down acetylcholine in the synaptic cleft.

Tropomyosin

A protein that blocks binding sites on actin filaments in a relaxed muscle.

Troponin

A protein complex that regulates muscle contraction by binding calcium ions.

Myosin Molecule

The thick filament protein that interacts with actin to produce muscle contraction.

Action Potential

A rapid electrical signal that travels along the muscle fiber membrane.

Axon Terminals

The endings of motor neurons that release neurotransmitters.