1. ELECTROCARDIOGRAM ECG
The ECG records the electrical activity of the heart.
If an electrode is placed so that wave of depolarization spreads toward the recording electrode, the ECG records a positive (upward) deflection.
If wave of depolarization spreads away from recording electrode, a negative (downward) deflection occurs.

2. Sinoatrial (SA) node [the pacemaker of heart] is located in right atrium.
Depolarization spreads from SA node across atria and results in the P wave.
Three tracts (Internodal fibers) within atria conduct depolarization to Atrioventricular (AV) node.

3. Conduction slows in AV node to allow atria to empty blood into ventricles before ventricular systole.
Bundle of His connects AV to bundle branches.
Purkinje fibers are terminal bundle branches.

4. ECG Complexes P wave QRS complex T wave P-Q interval Q-T interval
S-T segment

5. Conducting system
Pacemaker
S.A node
Internodal fibers
A.V node
Bundle of his
Bundle branch
Purkinje fibers

6. Electrocardiogram P wave QRS complex T wave P-Q interval Q-T interval
Depolarization of atria
Followed by contraction
QRS complex
3 waves (Q, R, & S)
Depolarization of ventricles
T wave
Repolarization of ventricles
P-Q interval
Q-T interval

7. Electrocardiogram P-Q interval (or P-R) Q-T interval
Time atria depolarize & remain depolarized
Q-T interval
Time ventricles depolarize & remain depolarized

8. P wave represents depolarization of atria which causes atrial contraction.
Repolarization of atria not normally detectable on an ECG

9. Excitation of bundle of His and bundle branches occur in middle of PR interval
QRS complex reflects depolarization of ventricles
T wave reflects repolarization of muscle fibers in ventricles

10. BLOOD PRESSURE Arterial Blood Pressure (BP)
The lateral pressure / force generated by the pumping action
of the heart on the walls of major vessels like aorta during
cardiac cycle.
BP is the pressure on arterial blood vessels per unit area.
Pressure inside big arteries (aorta & big vessels).

11. Measured in (mmHg)
By a device called Sphygmomanometer
Blood pressure has 2 components:
Systolic = mmHg.
Diastolic = mmHg.
Normal Range considered is 120/80 mmHg.

12. KOROTKOFF’S SOUND
While checking the blood pressure, after the placement
of diaphragm of stethoscope in the antecubital fossa
over the brachial artery, as the pressure is slowly
released from the inflated cuff, sounds are heard, that is
called korotkoffs sounds. When sounds are heard, that is
systolic blood pressure and when sounds disappear that
is diastolic blood pressure.

13. Diastolic pressure is more important, because
diastolic period is longer than the systolic period in
the cardiac cycle.

14. FACTORS DETERMINING BLOOD PRESSURE
Blood Pressure = Cardiac Output X Peripheral Resistance
(BP)
(CO)
Flow
(PR)
Diameter of arterioles
■ BP depends on:
1. Cardiac output  CO = SV X HR.
2. Peripheral resistance.
3. Blood volume.

15. Sex … M > F …due to hormones.
FACTORS AFFECTING BLOOD PRESSURE
Sex … M > F …due to hormones.
Age … Elderly > children …due to atherosclerosis.
Emotions … due to secretion of adrenaline/noradrenaline
Exercise … due to  venous return.
Hormones … (e.g.Adrenaline,noradrenaline,thyroid)
Gravity …  Lower limbs > upper limbs.
Sleep …  due to  venous return.
Pregnancy … due to  metabolism.