Physiology: Baroreceptor Reflex

Question 1

What is blood pressure?

Answer 1

the hydrostatic (outwards) pressure exerted by blood on blood vessel walls

Question 2

Systemic (Systolic) Arterial Blood Pressure

Answer 2

pressure exerted by blood on walls of aorta and systemic arteries when heart contracts (less 140 mm Hg)

Question 3

Systemic (Diastolic) Arterial Blood Pressure

Answer 3

pressure exerted by blood on walls of aorta and systemic arteries when heart relaxes (less 90 mm Hg)

Question 4

Hypertension

Answer 4

clinical blood pressure of 140/90 mm Hg (or higher)

Question 5

Pulse pressure

Answer 5

difference between systolic and diastolic blood pressures (e.g. 140 - 90 = 50mmHg)
-normally between 30 & 50

Question 6

Mean Arterial Blood Pressure (MAP)

Answer 6

average arterial blood pressure during a single cardiac cycle
(involves contraction and relaxation)

Question 7

MAP is not average of systolic and diastolic pressures

Answer 7

Diastolic portion is twice as long as systolic

Question 8

Estimating MAP

Answer 8

Simple: MAP = [ (2x diastolic) + systolic] ÷ 3 ]
MAP = DBP + 1/3 difference between SBP and DBP

Normal range MAP = 70 - 105 mmHg
(min. 60 needed to perfuse heart, brain and kidneys)

Question 9

MAP must be regulated

Answer 9

• to ensure pressure is high enough to perfuse internal organs
• not too high to damage blood vessels / strain heart

Question 10

Baroreceptors

Answer 10

sense pressure changes by responding to change in tension in arterial wall
(fast response to changes in blood pressure)