2. Below are some measured cardiovascular parameters in a healthy male subject.
ID: 226935 • Letter: 2
Question
2. Below are some measured cardiovascular parameters in a healthy male subject. You may want to diagram the circuit to help visualize the pressures and complete the calculations.
Parameter
Systolic pressure
124 mm Hg
Diastolic pressure
82 mm Hg
Pulse
73 beats/min
Left ventricular end-diastolic volume
140 ml
Left ventricular end-systolic volume
70 ml
Mean pulmonary artery pressure
15 mm Hg
Right atrial pressure
2 mm Hg
Left atrial pressure
5 mm Hg
a. From the information in the table above, calculate the mean arterial pressure (MAP) in this case. Explain why mean arterial pressure (MAP) is not a simple average of systolic and diastolic pressures.
b. Calculate the stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) for the subject at the time of measurement.
c. Now calculate the value for total pulmonary resistance and compare it to the value you just obtained for the systemic loop. Explain why there is such a difference between the resistances of the two loops.
d. What is the total blood flow (Q) through the pulmonary capillaries (collectively)?
e. If the diameter of the aorta is 48 mm, what is the approximate velocity of a blood cell traveling through the vessel? (disregard minor effects of turbulence, friction, etc).
Parameter
Systolic pressure
124 mm Hg
Diastolic pressure
82 mm Hg
Pulse
73 beats/min
Left ventricular end-diastolic volume
140 ml
Left ventricular end-systolic volume
70 ml
Mean pulmonary artery pressure
15 mm Hg
Right atrial pressure
2 mm Hg
Left atrial pressure
5 mm Hg
Explanation / Answer
To calculate mean arterial pressure (MAP) we use following formula
MAP = [Systolic blood pressure + 2(Diastolic blood pressure)] /3
= [124+2 (82)]/3= [124+164]/3 =96 mmHg
Stroke volume= End Diastolic Volume – End Systolic Volume =140 – 70=70mmHg
Cardiac output =Stroke volume x Heart rate =70 x 73 = 5110ml/min
Systemic vascular resistance or total peripheral resistance = 80 x[MAP- CVP] /Cardiac output
Where CVP is central venous pressure which is =[Right arterial pressure + Left arterial pressure] /2 =[2+5]/2 = 3.5mmHg
Total peripheral resistance= 80 x [96-3.5]/ 5110 =7400/5110 =1.45 dyn s cm5
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