Lab #13 - Blood Pressure and Cardiac Output Flashcards
Why is blood pressure important?
BP is related to blood flow
What is the equation for blood pressure?
BP = CO x TPR
What is TPR?
total peripheral resistance (of blood flow through the arteries)
Define systolic pressure. What is the normal value?
pressure in the arteries (aorta) created by contraction/emptying of the left ventricle
(100-120mmHg)
Define diastolic pressure. What are the normal values?
pressure in the arteries (aorta) when the left ventricle is relaxing/filling
(70-90mmHg; residual)
What type of fibers are arteries (aorta) made of? What does this allow for?
elastic fibers of arteries allow for elastic recoil (force that increases pressure in aorta)
Explain what happens to blood pressure when blood flow increases
↑BF = ↑elastic recoil and aorta walls push back = ↑TPR = ↑BP
Explain what happens to blood pressure when blood flow decreases
↓BF = ↓elastic recoil and aorta walls do not push back = ↓TPR = ↓BP
Define pulse pressure? What are the normal values?
difference between systolic and diastolic pressure
(30-50mmHg)
Define mean arterial pressure (MAP). What are the normal values?
average of BP; helps to indicate perfusion (BF) of blood to tissues
(70-110mmHg)
What is the equation for mean arterial pressure (MAP)?
MAP = systolic + 2(diastolic)/3
What blood vessel are we measuring when taking blood pressure?
aorta (artery)
How is blood pressure measured? What is a normal blood pressure?
systolic (first heart sound) / diastolic (last heart sound)
120/80
When using a blood pressure cuff, what does the first heart sound indicate (lub)? What does the last heart sound indicate (dub)?
first sound: AV valves closing
last sound: semilunar valves closing
When using a blood pressure cuff, what pressure are we measuring?
pressure in the brachial artery
Why is blood pressure “smaller” when laying down?
you are limiting the effects of gravity
Why is blood pressure higher when exercising?
increases in HR increase contractility/CO which increases BP
Why does blood pressure decrease and then increase when standing?
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
