Module 6 - BIO160

Cardiac muscle

Striated muscle found in the heart, involuntary control, contracts as a unit to pump blood.

Contractility

Ability of a muscle to shorten forcibly.

Elasticity

Ability of a muscle to stretch and rebound.

Excitability

Ability of a muscle to undergo neural stimulation.

Extensibility

Ability of a muscle to lengthen.

Skeletal muscle

Striated, multinucleated muscle that is under voluntary control and moves bones.

Smooth muscle

Non-striated, mononucleated muscle that is involuntary and found in internal organs.

Acetylcholine (ACh)

Neurotransmitter released at the neuromuscular junction to trigger muscle contraction.

Actin

Protein that makes up the thin myofilaments in a sarcomere.

Depolarize

To reduce the voltage difference across a muscle cell's plasma membrane.

Endomysium

Connective tissue covering each muscle fiber in a skeletal muscle.

Fascicle

A bundle of muscle fibers within a skeletal muscle.

Motor end-plate

Part of the sarcolemma at the neuromuscular junction with ACh receptors.

Myofibril

Long cylindrical structures that contain sarcomeres and run parallel to muscle fibers.

Neuromuscular junction (NMJ)

Synapse between motor neuron and muscle fiber membrane.

Perimysium

Connective tissue that surrounds fascicles within skeletal muscle.

Sarcomere

The contractile unit of skeletal muscle composed of myofilaments.

Sarcoplasmic reticulum (SR)

Specialized smooth endoplasmic reticulum that stores and releases calcium ions.

Troponin

Regulatory protein that binds to actin and calcium to expose myosin-binding sites.

Tropomyosin

Protein that covers myosin-binding sites on actin, preventing binding.

Fast glycolytic (FG) fibers

Muscle fibers primarily using anaerobic glycolysis, fatiguing quickly.

Slow oxidative (SO) fibers

Muscle fibers primarily using aerobic respiration, fatiguing slowly.

Hypertrophy

Increase in muscle mass due to the addition of structural proteins.

Atrophy

Decrease in muscle mass due to breakdown of structural proteins.

Auto-rhythmicity

Heart's ability to control its own contractions.

Intercalated discs

Connections between cardiac muscle cells that facilitate synchronized contraction.

Visceral muscle

Smooth muscle found in the walls of internal organs.

Agonist

Muscle whose contraction is responsible for producing a particular motion.

Antagonist

Muscle that opposes the action of an agonist.