Human Anatomy and Physiology - The Muscular System

A set of flashcards covering key vocabulary and concepts related to the muscular system from the lecture notes.

Muscular System

The organ system that enables movement, stability, respiration, communication, control of passageways, and heat production.

Endomysium

A thin layer of areolar connective tissue surrounding each muscle cell.

Perimysium

A thicker connective tissue layer that surrounds a fascicle.

Epimysium

The outer layer that covers the entire muscle belly and blends into connective tissue between muscles.

Fascia

Connective tissue that supports and protects muscles; includes deep and superficial fascia.

Fasciotomy

A surgical procedure to relieve pressure in compartment syndrome.

Direct attachment

Attachment where the epimysium is continuous with the periosteum of bones.

Indirect attachment

Attachment where the epimysium continues as a tendon or aponeurosis.

Fusiform muscles

Muscles that are moderately strong and have a spindle-like shape.

Parallel muscles

Muscles that span a great distance and can shorten significantly.

Convergent muscles

Muscles that are strong due to having a large number of fibers over length.

Pennate muscles

Muscles that have more fibers per length, providing more strength.

Circular muscles

Muscles that form a ring around body openings.

Excitability

The ability of muscle tissue to respond to chemical signals and electrical changes.

Contractility

The ability of muscle tissue to shorten actively and generate force.

Extensibility

The ability of muscle tissue to stretch and lengthen between contractions.

Elasticity

The ability of muscle tissue to return to its original resting length.

Sarcomere

The basic structural and functional unit of a muscle cell, extending from one Z disc to the next.

Motor unit

A motor neuron and all the muscle fibers it innervates, coordinating muscle contraction.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber where neurotransmitters are released.

ACh (Acetylcholine)

A neurotransmitter released at the neuromuscular junction, important for muscle contraction.

Action potential

A rapid electrical signal that travels along the sarcolemma and initiates muscle contraction.

T tubules

Infoldings of the sarcolemma that carry action potentials deep into muscle fibers.

Myofilaments

The contractile proteins found within muscle fibers, including thick (myosin) and thin (actin) filaments.

Cross-bridge

The connection formed when myosin heads bind to active sites on actin during contraction.

Power stroke

The process during muscle contraction when myosin pulls the thin filament past the thick filament.

Rigor Mortis

The postmortem stiffening of muscles due to the lack of ATP production and calcium leakage.

Calcium ions (Ca2+)

Ions that play a critical role in muscle contraction by binding to troponin.

Titin

A springy protein that anchors thick filaments to the Z disc in muscle fibers.

Sarcoplasm

The cytoplasm of a muscle fiber, containing myofibrils, glycogen, and myoglobin.

Sarcoplasmic reticulum

A smooth endoplasmic reticulum in muscle fibers that stores calcium ions.

Troponin

A protein that, when bound by calcium, causes tropomyosin to move and expose myosin binding sites.

Tropomyosin

A protein that blocks myosin binding sites on actin when muscles are relaxed.

Muscle metabolism

The biochemical process by which muscles generate energy for contraction.

Myosin ATPase

An enzyme in myosin heads that hydrolyzes ATP for energy during muscle contraction.