Lecture 10- Circulation of blood

Question 1

What is pulse pressure? and what is the average value?

Answer 1

The difference between systolic pressure and diastolic pressure average = 120/80 so 40

Question 2

What’s mean arterial pressure?

Answer 2

DP + 1/3(DP - SP)

Question 3

What happens to the value of mean arterial pressure as you age?

Answer 3

Vessels aren’t as healthy as you age so provide more friction so blood pressure increases

Question 4

In the ECG what is the P wave?

Answer 4

Atrial depolarization and contraction. (Atrial systole)

Question 5

IN the ECG what is the QRS complex?

Answer 5

Ventricle depolarization and contraction. Atrial reploarization happens but is masked by the big ventricular event.

Question 6

In the ECG what is the T wave?

Answer 6

Ventricle repolarization and relaxation

Question 7

What are the mechanical events of the Cardiac cycle ?(800ms)

Answer 7

1. Atrial systole begins
2. Atrial systole ends
3. Ventricular systole- phase 1 - contraction pushes AV valves close
4. V. systole phase 2- pressure in ventricles exceeds pressure in arteries and semilunar valves open and blood leaves.
5. Ventricular diastole early- ventricles relax, pressure drops, blood flows back into cusps of semilunar valves and forces them shut.
6. V. diastole, late- All chambers relaxed, ventricles fill passively.

Question 8

Which factors affect blood flow?

Answer 8

1. Length of vessel
2. Fluid viscosity
3. Radius of vessel

Question 9

What is Darcy’s Law?

Answer 9

Describes the flow of fluid through a porous medium.

F= dP/dR

(change in pressure at start to end of vessel/change in resistance)

Question 10

Which equation explains why radius has such a big affect on blood flow?

Answer 10

The poiseuille-Hagen equation