ATI RN
Multiple Choice Questions Muscular System Questions
Question 1 of 5
Which part of the rib cage includes true and false ribs?
Correct Answer: D
Rationale: Ribs (1-12) include true (1-7, direct sternal attachment) and false (8-12, indirect or none), forming the cage. Sternum connects ribs, thoracic vertebrae anchor them, costal cartilage links true ribs none encompass both types. Ribs' classification, per thorax, makes 'd' correct.
Question 2 of 5
A collection of similar tissues that performs a specific function is an
Correct Answer: A
Rationale: An organ, like the stomach, is a collection of similar tissues (e.g., muscle, epithelium) working together for a specific function (digestion). An organelle is a cellular structure (e.g., mitochondria), not tissues. An organism is the whole living entity. An organ system like the digestive system includes multiple organs, broader than one. The organ's tissue-based, functional unity, per anatomical hierarchy, makes 'a' correct.
Question 3 of 5
Which of the following is an example of a normal physiologic process that uses a positive feedback loop?
Correct Answer: B
Rationale: Childbirth uses a positive feedback loop: uterine contractions increase oxytocin, intensifying contractions until delivery, amplifying the stimulus. Blood pressure , fluid balance , and temperature use negative feedback to stabilize. Positive feedback's escalating nature in labor, per physiology, makes 'b' correct.
Question 4 of 5
Which muscle type(s) can be accurately described as visceral, nonstriated and involuntary?
Correct Answer: A
Rationale: Smooth muscle, found in visceral organs like the stomach and blood vessels, lacks striations due to its unorganized actin and myosin arrangement, unlike the sarcomeres of skeletal and cardiac muscle. It operates involuntarily, controlled by the autonomic nervous system, enabling functions like peristalsis without conscious effort. Skeletal muscle, attached to bones, is striated and voluntary, governed by the somatic nervous system for deliberate movements. Cardiac muscle, in the heart, is striated with intercalated discs and involuntary, but its rhythmic contractions distinguish it from smooth muscle's slower, sustained actions. Visceral typically denotes internal organs, aligning with smooth muscle's role, not cardiac or skeletal. Histologically, smooth muscle's spindle-shaped, uninucleate cells contrast with skeletal's multinucleate fibers and cardiac's branched structure. Physiological texts emphasize smooth muscle's unique calcium regulation via calmodulin, not troponin, reinforcing its distinct involuntary nature. This specificity clarifies why only smooth muscle fits all three descriptors, avoiding overlap with striated types.
Question 5 of 5
A continuous, sustained contraction that shows no relaxation is called
Correct Answer: A
Rationale: Complete tetanus occurs when rapid, repeated stimuli fuse muscle contractions into a sustained, maximal force with no relaxation phase. High-frequency nerve impulses (e.g., 50-100 Hz in humans) keep calcium levels elevated in the sarcoplasm, preventing actin-myosin cross-bridges from disengaging. A twitch is a single, brief contraction-relaxation cycle from one stimulus, lasting 20-100 ms. Incomplete tetanus, with slightly slower stimuli, shows partial relaxation between peaks. Wave summation adds force as stimuli increase before full relaxation, but retains distinct twitches. Treppe enhances force gradually without fusion. Complete tetanus, observable in lab settings or extreme exertion, maximizes tension up to 4-5 times twitch force reflecting sustained motor unit recruitment. Electromyography distinguishes its smooth plateau from twitch's spike or incomplete tetanus's ripples. Physiologically, it mimics intense efforts like lifting heavy loads, contrasting with transient or stepped responses, highlighting muscle's capacity for prolonged output under continuous stimulation.