Topic 11: Cardiovascular System - Blood Pressure Flashcards
What is blood pressure?
- hydrostatic pressure exerted by blood on wall of vessel
- clinically on the walls of arteries
Why does blood pressure occur in terms of flow and resistance?
occurs when flow is opposed by resistance
What is systolic pressure?
- produced by ventricular contraction against vascular resistance
What is diastolic pressure? (2)
- produced by elastic arteries against vascular resistance
- when ventricles are relaxed
When measuring bp in an artery, what numbers do we want to see?
120/80 systolic over diastolic
What is pulse pressure?
systolic - diastolic
What is Mean Arterial Pressure (MAP)? (3)
- regulated by body ie. what the body measures
- average blood pressure through cardiac cycle BUT diastole is longer than systole, so formula is
MAP = diastole P + 1/3 pulse pressure
MAP regulation formulas
What is change in pressure formula in relation to MAP?
deltaP = MAP - venous P
pressure in veins is around 0, so deltaP = MAP!!
MAP is regulated by controlling these 3 factors
1) cardiac output
2) TPR (arteriolar radius)
3) Blood volume
Why does blood volume affect MAP? (2)
- it affects venous return and therefore SV
- also MAP directly
in lecture, always regulated to have enough fluid to get to cells
What factors affect extrinsic control of MAP?
Neural and hormonal
What receptor reflexes are included in neural control extrinsically for MAP?
baroreceptors reflexes and chemoreceptor reflexes
What do baroreceptor reflexes monitor?
- short term changes ie. standing
Stretch receptors are a type of baroreceptor. Where do they monitor MAP in? (2)
- carotid sinus for brain bp
- aortic arch (systemic)
Baroreceptor reflexes diagram
What receptors are included in chemoreceptors for MAP? What do they do?
- peripheral chemoreceptors
- respond to pH, CO2, and O2
- chemoreceptors are involved in regulation of respiration, but affect bp
Where are chemoreceptors found?
- aortic arch and carotid sinus called bodies
chemoreceptor reflexes on MAP diagram
which hormones affect MAP? (3)
- epinephrine
- renin-angiotensin system
- Atrial Natriuretic Peptide (ANP)
What does epinephrine do to MAP? (2)
- increase HR, force of contraction
- therefore increases Cardiac output and MAP
renin-angiotensin System diagram
What does angiotensin II cause to MAP? (3)
1) increases vasoconstriction and venoconstriction, therefore increasing MAP
2) increases aldosterone and ADH, increasing renal Na+
- water absorbs, increasing thirst
- decreases blood vol, increasing MAP
What does angiotensin II cause to MAP? (3)
1) increases vasoconstriction and venoconstriction, therefore increasing MAP
2) increases aldosterone and ADH, increasing renal Na+
- water absorbs, increasing thirst
- decreases blood vol, increasing MAP
What does Atrial Natriuretic Peptide (ANP) cause? (4)
- decreased renin and therefore decreased angio II
- decreased aldosterone, ADH and therefore increased urine production and decreased blood vol
- decreases vasoconstriction
- so overall it decreases MAP
