A&P Exam 3 Final Vocabulary List

Comprehensive vocabulary flashcards covering articulations, muscle anatomy and physiology, and neurophysiology based on the A&P Exam 3 study guide.

Articulation

A joint; the place where two or more bones meet.

Synarthrosis

A functionally immovable joint.

Amphiarthrosis

A functionally slightly movable joint.

Diarthrosis

A freely movable joint.

Fibrous joint

A joint in which bones are connected by dense fibrous connective tissue.

Cartilaginous joint

A joint in which bones are connected by cartilage.

Synovial joint

A freely movable joint with a joint cavity; the most common type of joint.

Gomphosis

A fibrous joint in which a tooth fits into its socket.

Suture

A fibrous joint between bones of the skull.

Syndesmosis

A fibrous joint in which bones are connected by a ligament or interosseous membrane.

Symphysis

A cartilaginous joint in which bones are joined by fibrocartilage, such as the pubic symphysis.

Synchondrosis

A cartilaginous joint in which bones are joined by hyaline cartilage, such as a growth plate.

Joint cavity

The space between the articulating bones of a synovial joint.

Joint capsule

The connective-tissue enclosure surrounding a synovial joint.

Synovial fluid

Fluid in a synovial joint that lubricates the joint surfaces.

Plane joint

A synovial joint that allows gliding or sliding movements.

Hinge joint

A synovial joint that mainly allows flexion and extension.

Pivot joint

A synovial joint that allows rotation around a central axis.

Condylar joint

A synovial joint that allows movement in two planes, including flexion/extension and abduction/adduction.

Saddle joint

A synovial joint with saddle-shaped surfaces that allows movement in two planes.

Ball-and-socket joint

A synovial joint that allows movement in multiple directions, including rotation.

Flexion

A movement that decreases the angle between two body parts.

Extension

A movement that increases the angle between two body parts or straightens a joint.

Hyperextension

Extension beyond the anatomical position.

Lateral flexion

Bending the neck or trunk to the side.

Dorsiflexion

Moving the top of the foot toward the shin.

Plantar flexion

Pointing the foot downward, away from the shin.

Abduction

Movement away from the body's midline.

Adduction

Movement toward the body's midline.

Circumduction

Circular movement of a limb that combines flexion, extension, abduction, and adduction.

Rotation

Turning a bone around its longitudinal axis.

Pronation

Rotation of the forearm so the palm faces downward or posteriorly in anatomical position.

Supination

Rotation of the forearm so the palm faces upward or anteriorly in anatomical position.

Depression

Moving a body part inferiorly, or downward.

Elevation

Moving a body part superiorly, or upward.

Eversion

Turning the sole of the foot outward, away from the midline.

Inversion

Turning the sole of the foot inward, toward the midline.

Protraction

Moving a body part forward, or anteriorly.

Retraction

Moving a body part backward, or posteriorly.

Opposition

Moving the thumb across the palm toward the fingers.

Reposition

Returning the thumb from opposition to its anatomical position.

Tendon

Dense regular connective tissue that attaches muscle to bone.

Ligament

Connective tissue that connects bone to bone.

Cardiac muscle

Involuntary, striated muscle tissue found in the heart.

Smooth muscle

Involuntary, nonstriated muscle tissue found in the walls of hollow organs and vessels.

Skeletal muscle

Usually voluntary, striated muscle tissue generally attached to bones.

Excitability

The ability of muscle tissue to respond to a stimulus.

Contractility

The ability of muscle tissue to develop tension and shorten.

Extensibility

The ability of muscle tissue to be stretched.

Elasticity

The ability of muscle tissue to return to its resting length after being stretched or contracted.

Antagonist

A muscle that opposes or reverses the action of the agonist.

Agonist

The prime mover; the muscle primarily responsible for a particular movement.

Synergist

A muscle that assists the agonist in producing a movement.

Fixator

A muscle that stabilizes the origin of the agonist or another body part.

Origin

The attachment of a muscle that is generally less movable during contraction.

Insertion

The attachment of a muscle that is generally more movable during contraction.

Muscle naming: shape

A muscle may be named for its overall shape.

Muscle naming: action

A muscle may be named for the movement it produces.

Muscle naming: location

A muscle may be named for the body region or bone where it is located.

Muscle naming: fiber direction

A muscle may be named for the direction in which its fibers run.

Myocyte (muscle fiber)

A single muscle cell.

Myofibril

A contractile structure inside a muscle fiber, made up of repeating sarcomeres.

Actin

The thin filament in a sarcomere that interacts with myosin during contraction.

Myosin

The thick filament whose heads bind to actin and generate the power stroke.

Troponin

A regulatory protein that binds calcium and helps move tropomyosin away from actin's binding sites.

Tropomyosin

A regulatory protein that covers myosin-binding sites on actin when the muscle is relaxed.

Sarcoplasmic reticulum (SR)

A specialized membrane network in muscle fibers that stores and releases calcium.

Sarcolemma

The cell membrane of a muscle fiber.

Transverse tubules (T-tubules)

Invaginations of the sarcolemma that carry action potentials into the muscle fiber.

Motor end plate

The specialized region of the sarcolemma at the neuromuscular junction that contains acetylcholine receptors.

Sarcomere

The basic contractile unit of a myofibril, extending from one Z disc to the next.

Sliding filament model

The explanation of muscle contraction in which thin filaments slide past thick filaments, shortening the sarcomere.

Resting membrane potential (muscle)

The voltage across a resting muscle-fiber membrane; approximately $-90\,\text{mV}$, with the inside negative relative to the outside.

Neuromuscular junction (NMJ)

The synapse between a motor neuron and a skeletal muscle fiber.

Acetylcholine (ACh)

The neurotransmitter released by a motor neuron at the neuromuscular junction.

Ligand-gated channel

An ion channel that opens when a chemical messenger, such as ACh, binds to it.

Depolarization

A change in membrane potential that makes the inside of the cell less negative.

End-plate potential

A graded depolarization of the muscle membrane produced when ACh binds to receptors at the motor end plate.

Action potential (muscle)

A rapid electrical signal that travels along the sarcolemma and into the T-tubules.

Excitation-contraction coupling

The process by which a muscle-fiber action potential leads to calcium release and contraction.

Calcium ions ($\text{Ca}^{2+}$)

Ions released from the sarcoplasmic reticulum that bind to troponin and allow contraction to begin.

Crossbridge cycle

The repeating sequence in which myosin binds to actin, pulls, detaches using ATP, and resets.

Power stroke

The pivoting movement of a myosin head that pulls the thin filament toward the center of the sarcomere.

ATP

The immediate energy source used in muscle contraction, including to detach myosin from actin.

Creatine phosphate (creatine)

A stored high-energy phosphate source that can rapidly help regenerate ATP in muscle.

Myoglobin

An oxygen-binding protein in muscle that stores oxygen for use by muscle cells.

Glycolysis

A pathway that breaks down glucose to produce ATP; it can occur without oxygen.

Aerobic respiration

ATP production that uses oxygen to break down fuel molecules.

Lactate

A product associated with rapid glycolysis; its formation helps allow glycolysis to continue when energy demand is high.

Slow-twitch fibers

Muscle fibers with a strong capacity for aerobic ATP production and sustained activity.

Fast-twitch fibers

Muscle fibers suited to producing force quickly; they rely more heavily on rapid energy pathways.

Motor unit

One motor neuron and all the muscle fibers it controls.

Muscle tension

The force produced by a contracting muscle.

Muscle twitch

The brief contraction and relaxation response of a muscle fiber or motor unit to one stimulus.

Recruitment

Increasing muscle tension by activating additional motor units; also called spatial summation.

Wave summation

Increasing muscle tension by delivering stimuli more frequently so contractions build on one another; also called temporal summation.

Incomplete tetanus

A sustained, elevated muscle contraction with brief periods of partial relaxation.

Complete tetanus

A sustained muscle contraction with no visible relaxation between stimuli.

Refractory period (muscle)

A brief period after an action potential when the muscle membrane is less able or unable to respond to another stimulus.

Length-tension relationship

The relationship between a muscle's starting length and the amount of tension it can produce.