1. Blood Pressure Regulation

2. General Definitions:
Blood Flow: the volume of blood flowing through a vessel, organ or the entire circulation in a given period (ml/min)
Blood Pressure: the force exerted on a blood vessel by blood (mmHg)
Resistance: opposition to blood flow. A measure of friction within blood vessels
Blood Viscosity: thickness/ “stickiness” of blood itself, which will provide internal resistance to flow

3. Important Points Blood flow is controlled by changes in pressure
Blood will always flow from areas of high pressure to low pressure
Average blood pressure:
Right: 24/8 mmHg
Left: 120/80 mmHg
*Both sides eject the same volume of blood simultaneously

4. Cardiac Output CO= SV x HR
Cardiac Output (CO): the amount of blood pumped out by each ventricle in one minute
CO= SV x HR
Stroke volume (SV): the volume of blood pumped out by each ventricle in each beat
Heart rate (HR): the number of heart beats per minute
(CO also = EDV- ESV)

5. Regulations of Stroke Volume
1. Preload: amount that the ventricle is stretched when it is full of blood
2. Contractility: the contractile force of cardiac cells
3. Afterload: the pressure exerted by blood in the large arteries back on the heart

6. Mean Arterial Pressure (MAP)
The pressure that propels blood to the tissues throughout the cardiac cycle
Two ways to determine MAP:
1. MAP= diastolic pressure + 1/3 pulse pressure
2. MAP= CO x TPR

7. Total Peripheral Resistance
The total resistance to blood flow in the body
Affected mainly by:
Arteriolar radius
Blood viscosity

8. Blood Pressure Regulation
Short-term mechanisms:
Neural controls
Vasomotor center in brain
Baroreceptor reflexes
Chemoreceptor reflexes
Chemical controls
Sympathetic response (epinephrine)
ANP- decreases blood volume
ADH- conserves water
Angiotensin II- vasoconstriction
Inflammatory chemicals- vasodilation
Alcohol- inhibits ADH

9. Blood Pressure Regulation
Long-term mechanisms
Renal Regulation (kidney)
Renin-Angiotensin mechanism
Renin angiotensin
ADH
aldosterone