35. Blood circulation and heart function Flashcards
What type of system is the vascular system?
closed circulatory system
Cross-sectional area of 1 vessel
A = r² * pi
What is wall tension / circumferential stress?
The average force exerted circumferentially (perpendicular to both the axis and the radius) in the cylinder wall
Pressure in the aorta and arteries
100 mmHg
Flow rate in aorta and arteries
0.33 m/s
Flow rate in capillaries
0.0003 m/s
Flow rate in veins
0.22 m/s
5 auxiliary factors of circulation
- Arterial elasticity / windkessel
- Venous valves
- Muscle action
- Negative intrathoracic pressure
- Vertical movement of atrioventricular plane
What is systole?
Heart contraction
What is diastole?
Heart relaxation
What is the windkessel effect?
- 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
What does negative intrathoracic pressure help with?
draws air into the lungs and blood into the chest
What is the vertical movement of the atrioventricular plane?
AV plane moves towards the apex of heart during systole and goes back during diastole. Works like a pump
Which valves are between atria and ventricles
mitral and tricuspid
7 steps of the heart cycles
- Atrial contraction
- Isovolumetric contraction
- Rapid ventricular ejection
- Slow ventricular ejection
- Isovolumetric relaxation
- Rapid passive ventricular filling
- Slow passive ventricular filling
