Lab #13 - Blood Pressure and Cardiac Output

Question 1

Why is blood pressure important?

Answer 1

BP is related to blood flow

Question 2

What is the equation for blood pressure?

Answer 2

BP = CO x TPR

Question 3

What is TPR?

Answer 3

total peripheral resistance (of blood flow through the arteries)

Question 4

Define systolic pressure. What is the normal value?

Answer 4

pressure in the arteries (aorta) created by contraction/emptying of the left ventricle
(100-120mmHg)

Question 5

Define diastolic pressure. What are the normal values?

Answer 5

pressure in the arteries (aorta) when the left ventricle is relaxing/filling
(70-90mmHg; residual)

Question 6

What type of fibers are arteries (aorta) made of? What does this allow for?

Answer 6

elastic fibers of arteries allow for elastic recoil (force that increases pressure in aorta)

Question 7

Explain what happens to blood pressure when blood flow increases

Answer 7

↑BF = ↑elastic recoil and aorta walls push back = ↑TPR = ↑BP

Question 8

Explain what happens to blood pressure when blood flow decreases

Answer 8

↓BF = ↓elastic recoil and aorta walls do not push back = ↓TPR = ↓BP

Question 9

Define pulse pressure? What are the normal values?

Answer 9

difference between systolic and diastolic pressure
(30-50mmHg)

Question 10

Define mean arterial pressure (MAP). What are the normal values?

Answer 10

average of BP; helps to indicate perfusion (BF) of blood to tissues
(70-110mmHg)

Question 11

What is the equation for mean arterial pressure (MAP)?

Answer 11

MAP = systolic + 2(diastolic)/3

Question 12

What blood vessel are we measuring when taking blood pressure?

Answer 12

aorta (artery)

Question 13

How is blood pressure measured? What is a normal blood pressure?

Answer 13

systolic (first heart sound) / diastolic (last heart sound)

120/80

Question 14

When using a blood pressure cuff, what does the first heart sound indicate (lub)? What does the last heart sound indicate (dub)?

Answer 14

first sound: AV valves closing

last sound: semilunar valves closing

Question 15

When using a blood pressure cuff, what pressure are we measuring?

Answer 15

pressure in the brachial artery

Question 16

Why is blood pressure “smaller” when laying down?

Answer 16

you are limiting the effects of gravity

Question 17

Why is blood pressure higher when exercising?

Answer 17

increases in HR increase contractility/CO which increases BP

Question 18

Why does blood pressure decrease and then increase when standing?

Answer 18

Decreases initially when standing because you are now going against forces of gravity (blood wants to flow to lower body regions/toes), but the body will naturally increase heart rate to increase contractility/CO to increase BP (so that blood can flow to upper body regions). This explains why some people get dizzy when they immediately stand up after lying down