Question

1. What makes the heart beat?
2. Where does the electricity in the heart come from?
3. What causes a "mountain" and a "valley" in an ECG?
4. What is a "cardiac infarction"?
What is an electrocardiogram?

Answer 1

Answere :

Question 1 : The heart beat results from wave of electrical depolarization or action potential called cardiac impulse that originate in and is conducted along the tract of specialised cardiac muscle fibes called Purkinje fibres.

Question 2 : The electrical signal or cardiac impulse comes from pacemaker of heart i.e. S-A node which have unique property of self excitation. Self-exicitation in S-A node results from the spontaneous developement of an electric depolarization in its fibres.

Question 3 : The electric events which occur during cardiac cycle cause "mountain" and "valley" in an ECG. These events include depolarization and repolarization of the auricals and ventricals, bringing about thier contraction and relaxation.

Question 4 : Cardiac infraction or MI is a cardiac disorder caused by reduced blood flow in coronary artery due to blockage of an artery. It is commonly known as heart attack. It is irreversible damage of myocardiac tissue caused by prolonged hypoxia.

Electrocardiogram : It is a permanent record of electric events occuring during cardiac cycle made on a graph paper as a waveform.