What is the anatomical term for the knee joint?

Correct Answer: B

Rationale: The knee joint, or femorotibial joint, is between the femur and tibia, a hinge for leg movement. Humeroulnar is elbow, coxofemoral is hip, talocrural is ankle. Femorotibial's specificity, per joint nomenclature, makes 'b' correct.

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.

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.

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.

Correct Answer: C

Rationale: Range-of-motion exercises need to be frequent enough to maintain joint mobility and prevent stiffness, especially in patients at risk of contractures. Performing them 3 to 4 times a day ensures joints are moved through their full range multiple times, counteracting the effects of immobility without overtaxing the patient. Once a day is insufficient, as stiffness can develop within hours of inactivity. Twice daily (morning and afternoon) improves on that but may still allow periods of prolonged immobility. Four to six times might be ideal for severe cases but could exhaust the patient or staff resources unnecessarily. The 3 to 4 times recommendation balances efficacy and practicality, promoting flexibility and circulation while fitting into a realistic care schedule.