PHYS Regulation of MAP & The Cardiac Cycle Flashcards
MAP =
CO x TPR
MAP effect on baroreceptor AP firing
If MAP increases, baroreceptor AP firing increases.
If MAP decreases, baroreceptor AP firing decreases.
Relate valve opening, ECG presentation, blood flow & blood ejection timing.
1a)
Flat line of ECG.
Passive filling of the ventricles.
Blood flows from atrium -> ventricles.
1b)
SA node fires = P wave of ECG
Atria contract -> pressure in the ventricles rises.
2.
Sharp rise in ventricular pressure.
mitral/tricuspid valve closes = 1st heart sound (LUB) = QRS complex.
3.
Aortic/pulmonary valve opens -> Ventricular pressure > aortic pressure.
Blood ejected from the ventricle into the aorta = T wave = Ventricular repolarisation.
4.
Ventricular pressure < aortic pressure -> aortic/pulmonary valve closes
= 2nd heart sound (DUB).
After that, mitral/tricuspid valves open to restart cycle.
TPR =
Total Peripheral Resistance
MAP/CO
Korotkoff sounds of BP and corresponding PHYS
Phase 1: A sharp tapping.
This is the first sound heard as the cuff pressure is released. This sound provides the systolic pressure reading.
Phase 2: A swishing/whooshing sound.
Swishing sounds as the blood flows through blood vessels as the cuff is deflated.
Phase 3: A thump (softer than phase 1).
Intense thumping sounds that are softer than phase 1 as the blood flows through the artery but the cuff pressure is still inflated to occlude flow during diastole.
Phase 4: A softer, blowing, muffled sound that fades.
Softer and muffled sounds as the cuff pressure is released. The change from the thump of phase 3 to the muffled sound of phase 4 is known as the first diastolic reading.
Phase 5: Silence.
Silence that occurs when the cuff pressure is released enough to allow normal blood flow. This is known as the second diastolic reading.
Location of baroreceptors
Arch of aorta & carotid sinuses.
What is pulse pressure?
SBP - DBP
