Biology Forums - Study Force

So, in my notes, i copied down that if the Mean Arterial Pressure increases, Cardiac Output increases and if if MAP decreases, CO also decreases. Then I also wrote that if Resistance increases, Cardiac Output decreases and if Resistance decreases, CO will increase.

If thats the case tehn if Resistance decreases, CO will increases, so wouldnt MAP increase as well?

but my notes also says that if Resistance increases, MAP increases and if Resistance decreases, MAP decreases as well. So this is where im confused..

help?

its not a typo or i didnt copy the notes wrong...

do you think that the first sentence is referring to BLOOD PRESSURE not Mean Arterial Pressure?
because they're different...right?

i need someone to clarify this.

if thr BP decreases the cardiac output actually increases and that why we try to lower BO in heart failure. Is the resistance decreases so does the BP and CO increases.
Listen instead ot making notes

From the physics point of view, cardiac output, blood pressure and peripheral resistance are related to the amps, volts and ohms of Ohm's law. If the resistance stays the same, then an increase in cardiac output must be accompanied by a rise in blood pressure. If the resistance goes down and the pressure stays the same then the flow (the cardiac output) must increase. The relation is
Volts = amps x ohms
or
Blood pressure = cardiac output x resistance

The problem with the thinking is that in physics one generally starts with the voltage which drives the current, assuming the resistance stays constant. In physiology the cardiac output and the peripheral resistance may change together to determine the blood pressure, which is the other way round from the physics. Thus exercise will put up the cardiac output. The peripheral resistance may actually drop a bit, with redistribution of blood flow from internal organs to the opened vessels in the exercising muscle, but even so the blood pressure usually goes up. One situation where the peripheral resistance is the determining factor is in head injury, or other causes of raised intracranial pressure, where the peripheral resistance goes right up and so does the blood pressure.
In this context blood pressure and mean arterial pressure are the same thing. Yes, the blood pressure does vary through the cardiac cycle (systolic and diastolic values) but the cardiac output is a reflection of the mean.