Skeletal Muscle: Functions and Gross Anatomy

Which outcome best describes the function of skeletal muscle in heat production?

• Contraction stores ATP and reduces heat loss from skin

• Relaxation stores ATP and increases metabolic heat removal

• Contraction consumes ATP and releases heat to warm body

• Relaxation consumes ATP and releases heat to cool body

Which pairing correctly matches a connective tissue layer with what it surrounds?

• Epimysium surrounds the entire muscle organ

• Epimysium surrounds each fascicle within a muscle

• Endomysium surrounds bundles of fascicles only

• Perimysium surrounds each individual muscle fiber

A tear that disconnects muscle from bone most likely damages which structure?

• A cord-like tendon that anchors to bone

• A broad aponeurosis connecting muscle sheets

• The delicate endomysium around each fiber

• The sarcolemma lining the T-tubules

Electrical signals travel from the sarcolemma deep into a muscle fiber via structures that form part of a triad. Which choice correctly identifies these structures and their role?

• T-tubules store Ca2+; sarcolemma releases ATP for force

• Sarcolemma cisternae store Na+; T-tubules conduct K+

• Terminal cisternae conduct signals inward; T-tubules store Ca2+

• T-tubules conduct signals inward; SR cisternae release Ca2+

Which sarcomere region contains only thin filaments and shortens during contraction?

• I band, only thin filaments

• A band, entire thick filament

• H zone, only thick filaments

• M line, holds thick filaments

During muscle contraction, which band does NOT change length because it spans the entire thick filament?

• H zone of thick only

• A band across thick filament

• I band of thin filaments

• Z disc anchoring actin

Which protein complex binds Ca2+ to permit cross-bridge formation by uncovering myosin-binding sites?

• Troponin permits binding

• Tropomyosin blocks sites

• Nebulin stabilizes actin

• Dystrophin links membrane

A patient lacks functional dystrophin. Which sequence best explains the resulting pathology?

• More creatine phosphate fixes ATP

• Extra myoglobin reduces oxygen

• Stronger sarcolemma prevents damage

• Weak sarcolemma allows Ca2+ influx

Place these structures from largest to smallest organizational level in skeletal muscle.

• Muscle to myofilament order

• Sarcomere to fascicle order

• Myofibril to fascicle order

• Myofilament to muscle order

Tags

NGSS.HS-LS1-2

Which statement best describes the resting membrane potential in a skeletal muscle fiber at rest?

• About +30 mV with more Na+ outside

• About −90 mV with more K+ inside

• About −90 mV with more Na+ outside

• About −90 mV with more Na+ inside