ATI RN
Muscular System Multiple Choice Questions Questions
Question 1 of 5
Smooth muscle is different from skeletal muscle because smooth muscle
Correct Answer: A
Rationale: Smooth and skeletal muscles differ structurally and functionally. Smooth muscle lines artery walls, enabling involuntary constriction to regulate blood flow, unlike skeletal muscle, which attaches to bones for voluntary movement. Skeletal muscle is multinucleate and striated, lacking intercalated discs features of cardiac muscle not smooth muscle, which is uninucleate and non-striated. Smooth muscle's presence in visceral organs, controlled by the autonomic nervous system, contrasts with skeletal muscle's somatic control, highlighting its role in automatic processes like circulation, distinct from skeletal muscle's locomotive purpose.
Question 2 of 5
What is the source of the majority of the energy needed by muscles for physical activity that continues for longer than 30 or 40 minutes?
Correct Answer: D
Rationale: Sustained activity beyond 30-40 minutes relies on aerobic respiration in mitochondria, oxidizing pyruvate (from glycolysis) with oxygen to produce 36-38 ATP per glucose far more than stored ATP (seconds), glycolysis (minutes), or creatine phosphate (15 seconds). This efficient, oxygen-dependent process supports endurance, distinguishing it from short-burst energy sources, critical for prolonged muscle function in activities like running.
Question 3 of 5
Which of the following muscles is NOT named after its location in the body?
Correct Answer: B
Rationale: Adductor longus names its action (adduction) and size (long), not location, unlike latissimus dorsi (back), rectus femoris (thigh), and biceps brachii (arm). Located on the thigh, its name prioritizes function, distinguishing it from location-centric terms, useful for understanding muscle roles beyond positional cues.
Question 4 of 5
What action does the flexor carpi ulnaris perform?
Correct Answer: D
Rationale: The flexor carpi ulnaris flexes the wrist, bending it toward the forearm's palmar side, mirroring the flexor carpi radialis' action, differing only in position (ulnar vs. radial). It doesn't flex the arm or fingers, nor extend like its extensor counterpart. This wrist-specific flexion distinguishes it, key to hand positioning movements.
Question 5 of 5
The neurotransmitter that causes an action potential to occur in a muscle cell membrane is called:
Correct Answer: D
Rationale: Acetylcholine, released by somatic motor neurons, crosses the neuromuscular junction, binding sarcolemma receptors to depolarize the membrane, triggering an action potential. Inorganic phosphate and ADP relate to ATP cycling, calcium regulates contraction internally not membrane depolarization. Acetylcholine's neurotransmitter role initiates muscle activation, distinguishing it from intracellular or energy-related molecules, key to voluntary movement.