35. Blood circulation and heart function

Question 1

What type of system is the vascular system?

Answer 1

closed circulatory system

Question 2

Cross-sectional area of 1 vessel

Answer 2

A = r² * pi

Question 3

What is wall tension / circumferential stress?

Answer 3

The average force exerted circumferentially (perpendicular to both the axis and the radius) in the cylinder wall

Question 4

Pressure in the aorta and arteries

Answer 4

100 mmHg

Question 5

Flow rate in aorta and arteries

Answer 5

0.33 m/s

Question 6

Flow rate in capillaries

Answer 6

0.0003 m/s

Question 7

Flow rate in veins

Answer 7

0.22 m/s

Question 8

5 auxiliary factors of circulation

Answer 8

1. Arterial elasticity / windkessel
2. Venous valves
3. Muscle action
4. Negative intrathoracic pressure
5. Vertical movement of atrioventricular plane

Question 9

What is systole?

Answer 9

Heart contraction

Question 10

What is diastole?

Answer 10

Heart relaxation

Question 11

What is the windkessel effect?

Answer 11

• Arteries distand when blood pressure goes up (systole) and recoil when blood pressure goes down (diastole)
• Storage of blood in the aorta because more blood entering than leaving (peripheral resistance)
• Like a capacitor

Question 12

What does negative intrathoracic pressure help with?

Answer 12

draws air into the lungs and blood into the chest

Question 13

What is the vertical movement of the atrioventricular plane?

Answer 13

AV plane moves towards the apex of heart during systole and goes back during diastole. Works like a pump

Question 14

Which valves are between atria and ventricles

Answer 14

mitral and tricuspid

Question 15

7 steps of the heart cycles

Answer 15

1. Atrial contraction
2. Isovolumetric contraction
3. Rapid ventricular ejection
4. Slow ventricular ejection
5. Isovolumetric relaxation
6. Rapid passive ventricular filling
7. Slow passive ventricular filling

Question 16

What does the work of the heart characterize?

Answer 16

Work done by the left ventricle in a single stroke

Question 17

Formula work of the heart

Answer 17

L = pdV(1/2)mv²
p*dV : static / volumetric component
1/2mv² : dynamic (Ekin) component
dV : stroke volume

Question 18

Value of the average work of the heart

Answer 18

0.5 J