1. Human EKG

2. Heart: Review

3. Electrical Pathway of the Heart SA Node AV Node Bundle of His Right bundle branch Left bundle branch Inferior vena cava Purkinje fibers

4. EKG or ECG Electrocardiogram Willem Einthoven-1903 A record of the overall spread of electrical activity of the heart. What EKG actually records: 1)NOT a direct recording of electrical activity. Recording a portion of electrical activity induced in body fluids by cardiac impulse that reaches the surface of the body. 2)NOT a recording of a single AP in a single cell at a single point in time. Represents the SUM of electrical activity in all of cardiac muscle cells. 3)Represents comparisons in voltage detected by electrodes at two different points on the body’s surface. Not actual potential.

5. Einthoven’s Triangle Determines the electrical axis of the heart. Equilateral triangle. The vertices are at the left and right shoulders and the pubic region. The center corresponds to the vector sum of all electric activity occurring in the heart at any given moment. Based on 3 lead system. Now have 12 lead systems that are much more accurate. Einthoven’s law: At any instant the potential of any wave in lead II is equal to the sum of potentials in leads I and III.

6. Atrial Depolarization Ventricular Depolarization Ventricular Repolarization Diastole 80 mmHg Systole 120 mmHg

7. Why is atrial repolarization not represented on the figure?

8. Why Use EKG? Detect Arrhythmias – Irregular heart beat May indicate medical disorder or be due to physiological state. – Bradycardia = decrease heart rate (sinus node problem OR athlete) – Tachycardia = increase heart rate (imbalance of electrolytes OR exercise)

9. GroupMean HB (BPM) Resting Adult60-100 Adult male70 Adult female75 Teenager80-100 Child90-110 Toddler100-130 Infant130-150 Athlete50-60 (lowest ever 25) Sleep40 Exercise220 Lance Armstrong32-34 (resting) 201 (exercising) Elephant28 Shrew> 800

10. Today’s Lab EKG and Heart sounds. Only do lab on 2 group members. Only have to do resting EKG once for each member (ignore Experiment 1 in heart sounds lab).

11. Homework!!!! Answer all labscribe questions. Write a results and methods section for this lab. Please attach a data sheet with all of your RAW data. RAW data should not be a part of your results section!

12. Results Section Should concisely present your data. This section should have figures and/or tables AS WELL AS a paragraph explaining those data. Don’t interpret the data, however, you should point out any trends (i.e. heart rate increases with increased activity or average heart rate was lower in males than females).