ATI RN
Questions About Muscular System with Answers Questions
Question 1 of 5
The external intercostal muscles function in and the internal intercostal muscles function in
Correct Answer: B
Rationale: External intercostals lift ribs during inspiration, expanding the chest for inhalation. Internal intercostals depress ribs in forced expiration, aiding exhalation. Opposite pairing misaligns their roles. Trunk flexion or extension involves abdominals or back muscles, not intercostals. Their respiratory functions distinguish them, critical for breathing mechanics, unlike trunk movement roles.
Question 2 of 5
Which of the following will NOT be triggered by the release of acetyl choline in the synapse at the neuromuscular junction during muscle contraction?
Correct Answer: C
Rationale: At the neuromuscular junction, acetylcholine release initiates muscle contraction by binding to receptors on the muscle membrane, causing depolarization and an action potential that propagates along the fiber. This triggers calcium release from the sarcoplasmic reticulum, which binds to troponin, shifting tropomyosin to expose myosin-binding sites on actin, enabling contraction. These events form a direct cascade from acetylcholine's action. However, ATP binding to the myosin head occurs later in the cross-bridge cycle, detaching myosin from actin after a power stroke, a process not directly initiated by acetylcholine but part of the contraction-relaxation cycle powered by ATP hydrolysis. This distinction highlights that while calcium and actin exposure are immediate downstream effects, ATP's role is a subsequent step, reliant on energy dynamics rather than the initial synaptic signal, making it the exception in this sequence.
Question 3 of 5
Which of the following is NOT a shoulder muscle?
Correct Answer: D
Rationale: Shoulder muscles, like deltoid, supraspinatus, and teres minor, act on the shoulder joint. Deltoid abducts the arm, supraspinatus initiates abduction, and teres minor rotates it, all part of the rotator cuff or girdle musculature. Pectineus, in the thigh, flexes and adducts the hip, not the shoulder it's a medial thigh muscle. Subscapularis, another rotator cuff muscle, was replaced here to fit four options, but pectineus remains the outlier. Its hip-focused action contrasts with shoulder-specific roles, distinguishing it as unrelated to shoulder movement or stability in the musculoskeletal system.
Question 4 of 5
What endogenous substrate source provides the most energy during moderate to high intensity exercise?
Correct Answer: B
Rationale: Muscle glycogen provides the most energy during moderate to high-intensity exercise, like running or cycling, via glycolysis, rapidly yielding ATP anaerobically or aerobically. Stored in muscle (300-500g), it's directly accessible, powering sustained efforts as intensity limits fat oxidation. Liver glycogen (100g) supports blood glucose but depletes fast, less impactful locally. Intramuscular lipids contribute at lower intensities, insufficient for high demand. Adipose tissue lipids, vast but slow to mobilize, dominate in prolonged low-intensity states, not moderate-high. Muscle glycogen's quantity and rapid breakdown distinguish it, critical for intense performance, unlike smaller or slower sources.
Question 5 of 5
A muscle that has a pattern of fascicles running along the long axis of the muscle has which of the following fascicle arrangements?
Correct Answer: C
Rationale: Parallel fascicles run along a muscle's long axis, as in sartorius, maximizing range of motion with fibers aligned end-to-end. Circular fascicles (e.g., orbicularis oris) encircle openings, not axial. Pennate fascicles (e.g., deltoid) angle into a tendon, increasing force, not parallel. 'Rectus' describes straight muscles (e.g., rectus abdominis), often parallel, but parallel is the broader term. This arrangement suits lengthy, strap-like muscles, distinguishing it from circular closure, pennate power, or rectus specificity, key for motion range.