Muscle Tissue Review Flashcards

Comprehensive vocabulary flashcards covering skeletal muscle anatomy, cellular physiology, contraction mechanisms, energy metabolism, and major muscle actions based on the lecture slides.

Sarcomere

The functional unit of a skeletal muscle. They make up muscle cells

A band

The region of the sarcomere where thick filaments are found.

Titin

The elastic filament whose function is to connect myosin to the Z disc.

Tropomyosin

The regulatory protein that blocks myosin-binding sites in a resting muscle cell.

T tubules

The invaginations or infoldings of the sarcolemma that conduct electrical impulses into the interior of the myofiber.

Sarcoplasmic reticulum

The complex membrane structure where calcium is stored inside the muscle cell.

Troponin

The protein that calcium binds to in the sarcoplasm, causing tropomyosin to move and expose myosin-binding sites.

Terminal cisternae

Specific regions of the sarcoplasmic reticulum where calcium is stored and released in response to an action potential.

Epimysium

The connective tissue sheath that surrounds the entire muscle.

Endomysium

The connective tissue sheath that surrounds an individual muscle fiber.

Perimysium

The connective tissue sheath that surrounds a fascicle.

Tendon

A thick, ropelike structure that attaches the muscle to a bone, formed by the continuation of connective tissue sheaths.

Sarcolemma

The cell membrane of a muscle fiber.

Myofibrils

Long, cylindrical structures filling the myofiber, composed of back-to-back sarcomeres.

Z discs

Structures that anchor and stabilize the thin filaments and mark the boundaries of a sarcomere.

Actin and Myosin

The two contractile filaments found within a sarcomere.

Striations

The striped appearance of myofibers caused by alternating I and A bands.

I band

The region of the sarcomere containing only thin filaments.

H zone

The region of the sarcomere containing only thick filaments.

Triad

A functional unit formed by one T tubule and two terminal cisternae.

Cross bridge formation

The process that occurs when the myosin head binds to actin.

ATP

The substance that must bind to myosin heads to allow them to detach from thin filaments, and the first energy source used during intense activity.

Active transport

The process by which calcium reenters the terminal cisterns after muscle contraction is finished.

Neuromuscular junction

The site of communication between a motor neuron and a muscle, consisting of the motor endplate, axon terminal, and synaptic cleft.

Synaptic vesicles

The structures from which acetylcholine is released.

Acetylcholinesterase

The enzyme responsible for breaking down acetylcholine in the synaptic cleft.

Acetylcholine receptors

Ligand-gated sodium channels found on the motor endplate.

Action potential

An electrical impulse or current that spreads across the sarcolemma and down T-tubules to open voltage-gated $Ca^{++}$ channels.

Creatine phosphate

The molecule in the muscle cell that regenerates $ATP$ from $ADP$, acting as the second source of energy.

Glycolysis

An anaerobic process in the cytoplasm that produces a net of $2\,ATP$ and two pyruvate molecules; it is the third energy source used.

Aerobic respiration

A process occurring in the mitochondria that requires oxygen and produces about $36-28\,ATP$ through the Kreb's cycle and electron transport chain.

Sternocleidomastoid

The muscle responsible for flexing the neck.

Trapezius

The muscle responsible for extending the neck.

Deltoid

The muscle whose primary action is abducting the arm.

Pectoralis major

A muscle that acts as an arm adductor.

Triceps brachii

The muscle responsible for extending the elbow.

Biceps brachii

The muscle responsible for flexing the elbow.

Anterior tibialis

The muscle that causes dorsiflexion.

Gastrocnemius

The muscle that causes plantar flexion.

Hamstrings

The muscle group responsible for causing knee flexion.

Rectus femoris

The muscle responsible for causing knee extension.

Muscle Action Terms

Terms describing what a muscle does, including flexor, extensor, abductor, adductor, and pronator.

Muscle Size/Length Terms

Terms used in muscle naming including vastus, maximus, and longus.