Question

1. A normal healthy person has a stroke volume of 70 mL and a heart rate of 70 bpm. He is given a negative inotropic agent that decreases stroke volume to 50 mL. What would his heart rate need to be, in beats per minute, to maintain the same cardiac output? Round your answer to the nearest beat per minute..

2. Jolene wakes suddenly to her alarm clock and realizes that she is late for her 9:15am CBIO2210 class. She jumps to her feet, feels dizzy and lightheaded for a moment, then hops into the shower. Draw a diagram / flowchart / picture of the sequence of events that occurred when she jumped up that overcame her dizzy feeling and prevented her from losing consciousness. Include the receptors, the control center, at least one effector site, information traveling between receptors / control center / effectors, and the response.

Answer 1

1. Cardiac output = Heart Rate x Stroke volume

C.O. = 70 bpm x 70 mL

C.O = 4900 mL/ min

The cardiac output in situation A is 4.9 L/min.

After giving a negative Ionotropic Agent;

Considering Cardiac output remains the same-

4900 = Heart Rate x 50 mL;

Heart rate = 4900/50

Heart rate = 98 beats/min

After using the negative ionotropic agents, a decrease in stroke volume increases the heart rate from 70bpm to 98 bpm in order to maintain same cardiac output levels to regulate proper perfusion of gases and transport of nutrients across.