1. The Heart- PQRST and ECG
Digischool – Structure of the HumanHeart
Watch video but skip blank between 1 – 2 min
Cardiac cycle electrical impulse
An ECG

2. Monitoring your Heartbeat and Blood pressure

3. Electrocardiograph - text pg 305, Fig 9-27
An electrocardiogram or ECG records the electrical activity of the heart and monitors heart function. Irregular electrical signals can cause ineffective or unusual heartbeats. Each of the letters PQRST label a specific part of the electrical signals for a heartbeat. A normal heart beats 70 times a minute. 3

4. Electrocardiograph 1. P – Q wave
– the depolarization of the sino-atrial node
- Causes atrial systole
2. Q→R → S wave
– the depolarization of the atrio-ventricular node
- Causes ventricular systole 3. S → T wave - ventricles regain electrical charge
Atrial repolarization is NOT seen because it happens during the AV impulse 4

5. Electrocardiograph 5

6. Ventricular fibrillation is an abnormal heart rhythm that is disorganized and irregular. This is a heart attack and needs emergency treatment. 6

7. Ventricular tachycardia is a rapid, regular heart rhythm that originates in the lower chambers of the heart. Many people are healthy and have minor heartbeat irregularities. 7

8. ECG and the Heartbeat
The electrical signals in an ECG generate the heart contractions that make a heartbeat. The heart beat can be heard with a stethoscope. The blood pressure is measured with a sphygmomanometer.