Heart as a pump Flashcards
Diastole
Filling of the atria or ventricles with blood.
It coincides with muscular relaxation
Systole
Ejection or expulsion of blood from the atria or ventricles.
It coincides with muscular contraction.
From where does the Atria receive blood during ATRIA DIASTOLE?
receive blood from veins. Most of the blood (80%) diffuses passively from the atria (> pressure) to the ventricles (< pressure) due to the difference in pressures.
What happens during ATRIAL SYSTOLE?
ejects the remaining blood to the ventricles.
Name the events in the Atria during Systole- Diastole? (16)
- Depolarisation starts at SA node (p wave)
- Atrial depolarisation causes atrial systole emptying 25ml of blood into ventricles
(End-diastolic volume (EDV, IN VENTRICLE): 105 ml + 25 ml = 130 ml)
- Atrial repolarization starts. Atria relax = Atrial diastole.
- Start of ventricular depolarization (QRS wave at ECG)
- Ventricular depolarization will cause ventricular systole.
- The intraventricular pressure increases.
- AV valves close.
- Ventricle chamber closed during a brief period of time (≈0.03 s).
- Isovolumetric contraction: while contraction causes ventricular pressure to rise sharply, there is no overall change in volume because semilunar valves are closed
- The intraventricular pressure continues to increase.
- Semilunar valves open.
- Blood (70 ml, stroke volume) exits heart towards the aorta or pulmonary arteries (fast ejection followed by slow ejection).
- Isovolumetric relaxation: ventricles relax and the 4 valves are closed, so there is no change in ventricular volume.
- Ventricular repolarization (T wave in ECG) will cause ventricular diastole.
- The intraventricular pressure diminishes.
- Blood tends to return, closing the semilunar
meaning of iso
same
meaning of volume
volume
End diastolic volume in ventricles
105 ml + 25 ml = 130 ml
End systolic volume in ventricles
The volume that remains in the heart after the systole
EDV – Stroke Volume = 60 ml
fast ventricular filling
CHAMBERS
• Fast and passive ventricular filling with atrial blood.
• Ventricular volume
• Low ventricular pressure
VALVES
• AV valves: Opened
• Semilunar valves: Closed
slow ventricular filling
CHAMBERS
• Ventricles relaxed.
• Slow ventricular filling.
VALVES
• AV valves: Opened
• Semilunar valves: Closed
Atrial contraction
CHAMBERS
• Atrial contraction
• Final phase of ventricular filling
VALVES
• AV valves: Opened
• Semilunar valves: Closed
Isovolumetric contraction of the ventricles
CHAMBERS
• Isovolumetric ventricular contraction
• Increase in the ventricular pressure
• Constant ventricular volume
VALVES
• AV valves: Closed
• Semilunar valves: Closed
Fast ventricular ejection
CHAMBERS
Ventricular contraction Increase in the ventricular pressure (maximal)
Fast blood ejection (from left ventricle to aorta)
low Ventricular volume high Aortic pressure
VALVES
• AV valves: Closed
• Semilunar valves: Opened
slow ventricular ejection
reservoir of blood and the pressure
CHAMBERS
• Minimal ventricular volume
• low Speed of the blood ejection towards the aorta
• low Aortic pressure when the blood passes into the arteries
VALVES
• AV valves: Closed
• Semilunar valves: Opened
Isovolumetric ventricular relaxation
CHAMBERS • Isovolumetric ventricular relaxation • low Ventricular pressure • Constant ventricular volume • Filling of the atrial starts
VALVES
• AV valves: Closed
• Semilunar valves: Closed
What does the aorta and pulmonary trunk do during ventricular contraction?
The aorta and pulmonary trunk expand and store pressure in the elastic walls
What happens during Isovolumetric relaxation?
Elastic recoil (Rückstoß) of arteries.
The stored energy in the arteries sends blood toward
the circulatory system
What are heart sounds?
due to blood turbulences produced by the heart during the cardiac cycle that propagate through the tissues (blood, vessels, muscle) and can be detected in specific places of the body surface.
Whats the first sound for?
The first sound (“lubb”, S1) corresponds to the closing of AV valves at the beginning of ventricular systole.
Whats the second sound?
The second sound (“dup”, S2) is associated with the fast closing of semilunar valves. At the end of ventricular systole and beginning of the diastole.
Whats the third sound?
The third sound (occasional) is produced between the fast and slow filling phases.
It is due to ventricular vibrations caused by:
▪ Abrupt distension of the ventricular walls when blood enters the ventricles (fast filling)
▪ Abrupt stop of the flow’s speed (between fast and slow filling)
Whats the fourth sound?
The fourth sound (if heard = pathology) occurs during atrial systole.
It may be due to:
▪ Atrial contraction.
▪ Distension of the ventricles when blood passes through.
Whats a stenosis?
when valves do not open properly
