Cardiac Cycle Flashcards
1
Q
SA node
A
Pacemaker of the heart
2
Q
Atrial systole
A
- Contraction of the right and left atria pushing blood into the ventricles
- Atrial depolarization
- P wave
3
Q
Atrial diastole
A
- Period between atrial contractions
- Atrial repolarization
- QRS complex
4
Q
Ventricular systole
A
- Contraction of the right and left ventricles pushing blood into the pulmonary arteries and aorta
- Ventricular depolarization
- QRS complex
5
Q
Ventricular diastole
A
- Period between ventricular contractions
- Ventricular repolarization
- T wave
6
Q
Afterload
A
- Forces that impede the blood flow out of the heart
- Includes pressure in the peripheral vasculature, compliance of the aorta, and mass and viscosity of blood
7
Q
Stroke volume (SV)
A
- Volume of blood ejected by each contraction of the left ventricle
- 60-80ml is normal
8
Q
Cardiac output (CO)
A
- Amount of blood pumped from the right and left ventricle per minute
- SV x HR = CO
- 4.5-5.0 L/min (less in women)
- Can increase to 25 L/min with exercise
9
Q
Venous return
A
- Amount of blood that returns to the right atrium every minute
- Similar to CO volume
10
Q
ECG: P wave
A
- Atrial depolarization
- Atria contract
11
Q
ECG: PR interval
A
- Amount of time for atrial depolarization and conduction from the SA node to the AV node
- Normal duration: 0.12-0.20 sec
12
Q
ECG: QRS complex
A
- Atrial repolarization and ventricular depolarization
- Atria relax and ventricles contract
- Normal duration: 0.06-0.10 sec
13
Q
ECG: QT interval
A
- Amount of time for ventricular depolarization and repolarization
- 0.2-0.4 sec depending on HR
14
Q
ECG: ST segment
A
Isoelectric period following QRS complex when the ventricles are depolarized
15
Q
ECG: T wave
A
- Ventricular repolarization
- Ventricles relax
