A. The values obtained when measuring blood pressure, such as 120/80,
a) exactly match the pressures inside the ventricle during systole and diastole and reflect the pressure in the major arteries during ventricular systole and diastole.
b) All of the answers are correct. are the same on both the pulmonary and systemic circuits.
c) reflect the pressure in the major arteries during ventricular systole and diastole.
d) exactly match the pressures inside the ventricle during systole and diastole.
B. All of the following would cause an increase in blood pressure EXCEPT
a) an increase in arterial resistance.
b) a decrease in arterial diameter.
c) sympathetic stimulation.
d) a decrease in cardiac output.
The Correct Answer and Explanation is :
A. The correct answer is:
c) Reflect the pressure in the major arteries during ventricular systole and diastole.
Explanation:
Blood pressure readings such as 120/80 mmHg represent the pressure exerted by the blood on the walls of the arteries. The first number (120) is the systolic pressure, which is the pressure in the arteries when the heart’s ventricles contract (ventricular systole) and pump blood into the arterial system. The second number (80) is the diastolic pressure, which is the pressure in the arteries when the heart’s ventricles are relaxed (diastole) and filling with blood. These values correspond to the major arteries, such as the brachial artery, and not directly to the pressures inside the ventricles themselves.
The options a) and d) are incorrect because they suggest that the pressures directly match the pressure inside the ventricles, which is not the case. The pressures in the ventricles are higher during systole but lower during diastole compared to the systemic arterial pressure.
The option b) is incorrect because pressures on both the pulmonary and systemic circuits are not the same, as the pulmonary circuit (which carries blood from the heart to the lungs) operates at a much lower pressure than the systemic circuit (which pumps blood throughout the body).
B. The correct answer is:
d) A decrease in cardiac output.
Explanation:
Blood pressure is influenced by several factors, including cardiac output (the volume of blood the heart pumps per minute), arterial resistance (the resistance of blood flow in the arteries), and arterial diameter (the width of the arteries).
- An increase in arterial resistance (a) will increase blood pressure because the heart has to work harder to pump blood through the narrower or more resistant vessels.
- A decrease in arterial diameter (b) will also lead to increased blood pressure because smaller vessels offer more resistance to blood flow, which increases pressure in the arteries.
- Sympathetic stimulation (c) increases blood pressure by causing the heart to beat faster and more forcefully, as well as by constricting the blood vessels (vasoconstriction), which increases resistance.
On the other hand, a decrease in cardiac output (d) would decrease blood pressure because less blood is being pumped through the arteries. When the heart pumps less blood, the pressure in the arteries decreases. This is why a reduction in cardiac output, as a result of heart failure or other conditions, can lead to lower blood pressure.