What would be the heart rate of a person if the cardiac output is 5 L, blood volume in the ventricles at the end of diastole is 100 mL and at the end of ventricular systole is 50 mL?

Question

Cardiac activities of the heart are regulated by: A. Nodal tissue
B. A special neural centre in the medulla oblongata
C. Adrenal medullary hormones
D. Adrenal cortical hormones
Choose the correct answer from the options given below:

Answer 1

The heart rate of a person can be calculated using the formula for cardiac output (CO), which is the total volume of blood pumped by the heart per minute. The formula is given by:

CO = SV \times HR

where:

CO is the cardiac output,
SV is the stroke volume, and
HR is the heart rate.

We are given that the cardiac output (CO) is 5 liters per minute (5000 mL per minute).

To find the stroke volume (SV), we use the difference in blood volume in the ventricles at the end of diastole and the end of systole:

SV = EDV - ESV

EDV (End-Diastolic Volume) is 100 mL,
ESV (End-Systolic Volume) is 50 mL.

Thus, the stroke volume SV is:

SV = 100 \, \text{mL} - 50 \, \text{mL} = 50 \, \text{mL}

Substituting the values into the cardiac output formula:

5000 \, \text{mL/min} = 50 \, \text{mL} \times HR

Solving for HR (heart rate):

HR = \frac{5000}{50} = 100 \, \text{beats per minute}

Therefore, the correct answer is 100 beats per minute.

Answer 2