Application for Exam: Neuro, Muscle, and Cardio

Patient Scenario: A patient presents with sudden unilateral facial drooping and is unable to furrow their brow or close the eye on that side. Which cranial nerve is impaired?

Cranial Nerve VII (Facial nerve)

Patient Scenario: A patient exhibits spasticity, hyperreflexia, and an upward extensor toe response (positive Babinski sign). Which motor neuron division is damaged?

Upper motor neurons (UMN)

Patient Scenario: A $70$-year-old patient exhibits a resting tremor, bradykinesia, and postural instability. The loss of neurons producing which neurotransmitter in the substantia nigra explains these signs?

Dopamine

Patient Scenario: A patient experiences muscle weakness and drooping eyelids (ptosis) that worsen after exertion. Autoantibodies targeting which membrane receptor at the neuromuscular junction are responsible?

Nicotinic acetylcholine ($ACh$) receptors

Patient Scenario: In a state of extreme metabolic exhaustion, muscle fibers remain locked in a contracted state because cross-bridges cannot release. The absence of which specific molecule prevents myosin from releasing actin?

Adenosine triphosphate ($ATP$)

Patient Scenario: A patient presents with dyspnea, orthopnea, and bilateral pulmonary crackles on auscultation. Which chamber of the heart has failed to pump blood forward adequately?

Left ventricle

Patient Scenario: A patient with crushing chest pain has ST-segment elevation across leads $V<em>1$ through $V</em>4$. Occlusion of which coronary vessel typically causes this anterior wall infarction?

Left anterior descending ($LAD$) artery

Patient Scenario: An $ECG$ shows regular rhythm but a prolonged $PR$ interval measuring greater than $0.20\,\text{s}$, with every P wave followed by a QRS complex. What is this rhythm diagnosis?

First-degree atrioventricular ($AV$) block