ATI RN
Muscular System Exam Questions Questions
Question 1 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 2 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 3 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.
Question 4 of 5
When the patient returns to the unit from having had an arthrogram, which intervention will the nurse perform first?
Correct Answer: B
Rationale: After an arthrogram, where contrast dye is injected into a joint, the priority is managing potential swelling or discomfort from the procedure. Applying ice packs reduces inflammation and numbs mild pain, addressing immediate post-procedure effects. Ambulating the patient might worsen swelling or discomfort before it's controlled. Passive range-of-motion exercises could irritate the joint further, especially without first reducing inflammation. Wrapping with an elastic bandage helps with support but doesn't directly address swelling as effectively as ice in the initial stage. Ice is the first step because it tackles the physiological response to the injection, setting the stage for subsequent interventions like compression or movement, ensuring patient comfort and recovery.
Question 5 of 5
The nurse is caring for a patient who has had an arthrocentesis. The nurse has completed discharge instructions. Which statement by the patient indicates the need for further instruction?
Correct Answer: A
Rationale: Arthrocentesis, removing fluid from a joint, aims to relieve pressure and improve mobility. Saying the knee mustn't move for 1-2 weeks suggests misunderstanding, as gentle movement is typically encouraged soon after to prevent stiffness, with rest limited to a day or two unless specified otherwise. Steroids reducing inflammation is accurate, as they're often injected post-procedure. Expecting some pain aligns with recovery, as does wearing a bandage for 2-3 days for support. The prolonged immobility statement requires correction, as it contradicts the goal of restoring function, risking complications like adhesions further teaching ensures the patient balances rest and activity correctly.