Mean circulatory filling pressure is?
Correct Answer: Arterial pressure taken at the point when heart stops beating
Description: Ans. is 'd' i.e. Arterial pressure taken at the point when heart stops beating Mean circulatory filling pressure:Normally the mean arterial pressure is quite high (approx 100 mm Hg) and the venous pressure quite low (approx 2 mm Hg); this pressure difference results in the flow of blood across the total peripheral resistance. If the heart is suddenly stopped, blood would continue to flow across the microcirculation, propelled by the recoiling arterial capacitance. Arterial pressure would fall as blood leaves the arterial compartment and venous pressure would rise as blood is shifted into the venous compartment. Flow through the microcirculation will stop only when arterial and venous pressures are equal. The equilibrium pressure that is reached throughout the cardiovascular system when cardiac output is stopped is called the mean circulatory filling pressure.For average man, mean circulatory filling pressure is about 7 mmHg.It is determined by the amount of blood within the cardiovascular system and the capacitance of the blood vessels. The greater the volume of blood in the circulation, the greater is the mean circulatory filling pressure as blood stretches the walls of the vasculature.Withdrawing blood from a patient will decrease the mean circulatory filling pressure. If blood were removed until the mean circulatory filling pressure fell to zero (i.e. no stretch on the blood vessel walls), the system would still contain an appreciable amount of blood (approx 4 liters). This volume of blood is called the unstressed volume.Mean systemic filling pressure:The mean systemic filling pressure is slightly different from the mean circulatory filling pressure.The mean systemic filling pressure is the pressure measured everywhere in the systemic circulation after blood flow has been stopped by clamping the large blood vessels at the heart, so that the pressure in the systemic circulation can be measured independently from those in the pulmonary circulation. The mean systemic filling pressure is however almost always nearly equal to the mean circulatory filling pressure.Also see:Pulse pressure: it is the difference between the systolic and diastolic pressures.Mean arterial pressure:Mean arterial pressure is the average pressure throughout the cardiac cycle. As the systole is shorter than the diastole, the mean arterial pressure is slightly less than the value midway between the systolic and the diastolic pressure.
Category:
Physiology
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