Final answer:
Damage to the vagus nerve would likely result in decreased responsiveness of the baroreceptor reflex because the vagus nerve plays a crucial role in the parasympathetic regulation of heart rate and stroke volume.
Step-by-step explanation:
Damage to the vagus nerve would most likely lead to a decrease in the responsiveness of the baroreceptor reflex. The vagus nerve provides parasympathetic innervation to the heart, including influencing the cardiac reflexes by modulating heart rate and stroke volume. When the baroreceptor firing decreases, the cardiac centers in the brain normally increase sympathetic stimulation and decrease parasympathetic stimulation via the vagus nerve to raise the heart rate and cardiac output. This response compensates for low blood pressure or blood loss. However, if the vagus nerve is damaged, its ability to decrease heart rate and stroke volume in response to an increase in blood pressure gets impaired, leading to a decreased responsiveness of the baroreceptor reflex that normally helps balance blood pressure and cardiac function.