Question

Predict what would happen to heart rate (HR), stroke volume (SV), and cardiac output (CO) with increased sympathetic input.

a. Decreased HR, decreased SV, and decreased CO

b. Increased HR, decreased SV, and increased CO

c. Increased HR, increased SV, and increased CO

Answer 1

With increased sympathetic input, heart rate (HR) and stroke volume (SV) would increase, leading to an increased cardiac output (CO).

Step-by-step explanation:

The question concerns the effects of increased sympathetic input on heart rate (HR), stroke volume (SV), and cardiac output (CO). With increased sympathetic stimulation, there is typically an increase in heart rate and stroke volume, which together lead to an increase in cardiac output. The sympathetic nervous system acts to prepare the body for 'fight or flight' situations, hence increasing the heart's activity. The medulla oblongata's cardiovascular centers regulate this process, increasing HR and SV by releasing catecholamines such as epinephrine and norepinephrine that prepare the body for increased physical activity. Therefore, the correct prediction for what would happen to HR, SV, and CO with increased sympathetic input is option c: Increased HR, increased SV, and increased CO.