Anatomy 102: Muscular System

Question 1

Muscular System

Accepted Answer

The organ system responsible for body movement, posture maintenance, heat production, and stabilization of joints, consisting of over 600 skeletal muscles.

Question 2

Skeletal Muscle

Accepted Answer

Voluntary, striated muscle tissue attached to bones by tendons that produces conscious body movements.

Question 3

Smooth Muscle

Accepted Answer

Involuntary, non-striated muscle tissue found in the walls of hollow organs (stomach, intestines, blood vessels) that controls involuntary movements.

Question 4

Cardiac Muscle

Accepted Answer

Involuntary, striated muscle tissue found only in the heart that contracts rhythmically to pump blood throughout the body.

Question 5

Muscle Fiber

Accepted Answer

A single, multinucleated skeletal muscle cell that can be several centimeters long and contains many myofibrils.

Question 6

Myofibril

Accepted Answer

A long, cylindrical organelle within a muscle fiber composed of repeating units called sarcomeres that enable contraction.

Question 7

Sarcomere

Accepted Answer

The basic contractile unit of a myofibril, bounded by Z-lines and containing overlapping actin (thin) and myosin (thick) filaments.

Question 8

Actin

Accepted Answer

A thin protein filament in the sarcomere that interacts with myosin to produce muscle contraction through the sliding filament mechanism.

Question 9

Myosin

Accepted Answer

A thick protein filament in the sarcomere with head groups that bind to actin and pull it inward during contraction using ATP hydrolysis.

Question 10

Sliding Filament Theory

Accepted Answer

The mechanism of muscle contraction in which myosin heads pull actin filaments toward the center of the sarcomere, shortening the muscle fiber.

Question 11

Neuromuscular Junction

Accepted Answer

The synapse between a motor neuron and a skeletal muscle fiber where acetylcholine is released to trigger muscle contraction.

Question 12

Motor Unit

Accepted Answer

A single motor neuron and all the skeletal muscle fibers it innervates. Smaller motor units allow finer control of movement.

Question 13

Muscle Contraction

Accepted Answer

The process by which muscle fibers generate tension through the interaction of actin and myosin filaments, requiring calcium ions and ATP.

Question 14

Antagonist Muscle

Accepted Answer

A muscle that opposes the action of another muscle (the agonist). For example, the triceps is the antagonist to the biceps during elbow flexion.

Question 15

Agonist (Prime Mover)

Accepted Answer

The muscle primarily responsible for producing a specific movement (e.g., the biceps brachii is the agonist during elbow flexion).

Question 16

Synergist Muscle

Accepted Answer

A muscle that assists the agonist in performing a movement by stabilizing joints or reducing unnecessary motion.

Question 17

Flexion

Accepted Answer

A movement that decreases the angle between two body parts at a joint (e.g., bending the elbow).

Question 18

Extension

Accepted Answer

A movement that increases the angle between two body parts at a joint (e.g., straightening the elbow).

Question 19

Isometric Contraction

Accepted Answer

A muscle contraction in which tension is generated but the muscle length does not change (e.g., holding a heavy object in a fixed position).

Question 20

Isotonic Contraction

Accepted Answer

A muscle contraction in which the muscle changes length while maintaining constant tension, producing movement (concentric or eccentric).

Question 21

Muscle Tone

Accepted Answer

The continuous, low-level contraction of muscles that maintains posture and keeps muscles firm and ready for action.

Anatomy 102: Muscular System

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