Topic 11: Cardiovascular System - Blood Pressure

Question 1

What is blood pressure?

Answer 1

• hydrostatic pressure exerted by blood on wall of vessel
• clinically on the walls of arteries

Question 2

Why does blood pressure occur in terms of flow and resistance?

Answer 2

occurs when flow is opposed by resistance

Question 3

What is systolic pressure?

Answer 3

• produced by ventricular contraction against vascular resistance

Question 4

What is diastolic pressure? (2)

Answer 4

• produced by elastic arteries against vascular resistance
• when ventricles are relaxed

Question 5

When measuring bp in an artery, what numbers do we want to see?

Answer 5

120/80 systolic over diastolic

Question 6

What is pulse pressure?

Answer 6

systolic - diastolic

Question 7

What is Mean Arterial Pressure (MAP)? (3)

Answer 7

• 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

Question 8

MAP regulation formulas

Answer 8

Question 9

What is change in pressure formula in relation to MAP?

Answer 9

deltaP = MAP - venous P
pressure in veins is around 0, so deltaP = MAP!!

Question 10

MAP is regulated by controlling these 3 factors

Answer 10

1) cardiac output
2) TPR (arteriolar radius)
3) Blood volume

Question 11

Why does blood volume affect MAP? (2)

Answer 11

• it affects venous return and therefore SV
• also MAP directly
  in lecture, always regulated to have enough fluid to get to cells

Question 12

What factors affect extrinsic control of MAP?

Answer 12

Neural and hormonal

Question 13

What receptor reflexes are included in neural control extrinsically for MAP?

Answer 13

baroreceptors reflexes and chemoreceptor reflexes

Question 14

What do baroreceptor reflexes monitor?

Answer 14

• short term changes ie. standing

Question 15

Stretch receptors are a type of baroreceptor. Where do they monitor MAP in? (2)

Answer 15

• carotid sinus for brain bp
• aortic arch (systemic)

Question 16

Baroreceptor reflexes diagram

Answer 16

Question 17

What receptors are included in chemoreceptors for MAP? What do they do?

Answer 17

• peripheral chemoreceptors
• respond to pH, CO2, and O2
• chemoreceptors are involved in regulation of respiration, but affect bp

Question 18

Where are chemoreceptors found?

Answer 18

• aortic arch and carotid sinus called bodies

Question 19

chemoreceptor reflexes on MAP diagram

Answer 19

Question 20

which hormones affect MAP? (3)

Answer 20

• epinephrine
• renin-angiotensin system
• Atrial Natriuretic Peptide (ANP)

Question 21

What does epinephrine do to MAP? (2)

Answer 21

• increase HR, force of contraction
• therefore increases Cardiac output and MAP

Question 22

renin-angiotensin System diagram

Answer 22

Question 23

What does angiotensin II cause to MAP? (3)

Answer 23

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

Question 24

What does angiotensin II cause to MAP? (3)

Answer 24

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

Question 25

What does Atrial Natriuretic Peptide (ANP) cause? (4)

Answer 25

• 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