Hemodynamics Flashcards
How much O2 is still in deoxygenated blood at rest?
70%
Flow (arteries and veins) =
Pressure/resistance
Resistance in the system is determined by
arterioles
The pressure gradient in the systemic system is
125 (aorta) to 25 (capillaries)
The pressure gradient in the pulmonary circuit is
10 (pulmonary vein) to 5 (vena cava)
Why is the systemic pressure so much higher?
Systemic pressure is higher because it experiences 5 times the resistance.
Which side of the heart works harder?
the left ventricle
Flow (capillaries) =
velocity and cross-sectional area
Poisuelle’s Law
= π/8 (Initial pressure – End Pressure) x radius4
Distance x viscosity of blood
According to the carotid baroreceptor reflex
increased BP stretches the carotid arteries causing baroreceptors to
- Decrease HR
- Decrease stroke volume
- Cause vasodilation
According to the Bainbridge reflex
increased venous return and increased pressure in the vena cavae and right atrium causes
- an increase in HR
The components of the cardiac cycle are
- Fast rapid filling phase
- Diastasis
- 2nd rapid filling phase
- isovolumetric contraction
- Rapid ejection
- Isovolumetric contraction
During the first rapid filling phase
- 2/3 ventricular volume filled
- Atrial P exceeds ventricular P
During the diastasis phase
- Atrial P exceeds Ventricular P
- slow filling of ventricles (small amount)
2nd rapid filling phase
- Atrial P exceeds Ventricular P
- Atria contract filling the ventricles
- remaining 1/3 of ventrical volume filled
- Fourth heart sound
