Control of MAP 1 Flashcards
What is the normal range of blood pressure?
140/90mmHg
What do the korotkoff sounds indicate?
1st sound- peak of systloic pressure
2/3rd sound- turbulent flow as BP exceeds cuff pressure intermittently.
4th sound- muffled sound due to minimum diastolic pressure.
No sound heard thereafter.
What is MAP?
Average arterial BP during a Single cardiac cycle.
How is MAP calculated?
(Systolic BP) + (2 x Diastolic BP)/ 3
Cos diastole is twice as long as systole in a cardiac cycle.
Average value- 93.3 mmHg
How else can MAP be measured?
DBP + 1/3rd (SBP-DBP)
What is pulse?
SBP- DBP
Normal range of MAP?
70-105mmHg.
MAP needs to be at least 60mmHg to perfuse the brain, kidneys and coronary arteries.
What is the equation of MAP?
MAP = CO X TPR.
What is the equation for CO?
CO = SV X HR.
CO volume of blood pumped from each ventricle per minute.
SV same as move but per heart beat.
What is TPR?
Sum of resistance of all peripheral vasculature.
What are the major vessels of resistance?
Arterioles.
Which part of the brain is the control centre of the heart?
Medulla
Where is the location of the baroreceptors?
- Carotid Sinus (9th CN)
2. Aortic arch (10th CN)
What do the barorceptors do when MAP is low when a person stands up after lying down?e
- MAP transiently decreases.
- Venous return decreases, gravity.
- Vagal nerve firing decreases.
- Sympathetic stimulation increased HR and SV increases.
- Sympathetic Constrictor Tone increased TPR increased (arterioles)
- Constrictor Tone Vasoconstriction Increased Venous return.
So HR, SV, TPR increase= increased MAP
What happens in postural hypotension?
Baroreceptors fail to correct the fall in MAP when the person stands up
