ATI RN
Muscular System Exam Questions Questions
Question 1 of 5
What is the primary function of the hyoid bone?
Correct Answer: B
Rationale: The hyoid bone, free-floating in the neck, anchors tongue and larynx muscles (e.g., genioglossus), aiding speech/swallowing. It doesn't support the skull , protect thorax , or form skull base (d, occipital). Its muscular role, per anatomy, makes 'b' correct.
Question 2 of 5
Metabolism can be defined as the
Correct Answer: D
Rationale: Metabolism is the sum of all chemical reactions in an organism, including catabolism (breaking down) and anabolism (building up), powering life processes like growth. Adjustment to changes is homeostasis, not metabolism. Cell specialization is differentiation, new cell formation is regeneration distinct processes. Metabolism's comprehensive chemical scope, per physiology, makes 'd' correct.
Question 3 of 5
To make a banana split, you halve a banana into two long, thin, right and left sides along the
Correct Answer: C
Rationale: The midsagittal plane divides the banana (or body) into equal right and left halves lengthwise, matching the split's vertical, midline cut. Coronal splits front-back, longitudinal is vague (often sagittal), transverse cuts horizontally. Midsagittal's symmetry, per planes, makes 'c' correct.
Question 4 of 5
The A band in a muscle appears and contains
Correct Answer: A
Rationale: The A band, a sarcomere's dark-staining region under a microscope, spans the length of thick myosin filaments, overlapping with thin actin filaments in its outer zones. This overlap causes its anisotropic property, scattering light and appearing dark, unlike the isotropic (I) band's lighter, actin-only composition. Thick filaments anchor at the M line, while thin filaments extend from Z lines, partially interdigitating within the A band during rest. This dual presence distinguishes it from the H zone (thick only) and I band (thin only). The dark appearance stems from dense protein packing, observable in electron micrographs, and remains constant in length during contraction, unlike shrinking I bands. Thin filaments alone wouldn't account for the A band's width or darkness, nor would thick filaments without actin overlap explain its full structure. Muscle physiology texts confirm this composition, critical for cross-bridge formation in contraction, making the A band's dual-filament nature a cornerstone of sarcomere function.
Question 5 of 5
Calcium is stored and released in skeletal muscle by the
Correct Answer: B
Rationale: The sarcoplasmic reticulum (SR), a specialized endoplasmic reticulum in skeletal muscle, stores and releases calcium to trigger contraction. Surrounding myofibrils, it sequesters calcium via calsequestrin, maintaining low cytosolic levels (10^-7 M) at rest. Upon T-tubule-transmitted action potentials, SR terminal cisternae release calcium (rising to 10^-5 M) through ryanodine receptors, binding troponin to initiate actin-myosin interaction. The sarcolemma conducts the initial depolarization, not storage. T-tubules relay signals inward but lack storage capacity. Caveoli (likely a typo for caveolae) are membrane invaginations, irrelevant here. Myofilaments use calcium but don't store it. The SR's role, detailed in muscle physiology, is critical: its ATPase pumps reuptake calcium post-contraction, relaxing the fiber. Electron microscopy reveals its extensive network, ensuring rapid, uniform calcium spread, distinguishing it from signal-conducting or contractile structures in excitation-contraction coupling.