Recording of Cardiogram – demonstration

 

Study of Normal Cardiogram

Aim: To study the normal cardiogram.

Apparatus and reagents required:

 Kymogram machine, rotator drum, live frog ,  thread, Smoked paper, arrow,  ringer solution.

Ringer solution :

Preparation of the

 Follow the directions in the frog heart movie on line and the step below:

 1. Obtain a double-pithed  frog

 2. Place the frog on its dorsal surface.

 3. Using the sharp end of a pair of blunt/sharp scissors make a small penetration into the abdominal cavity of the frog.

 3. Carefully cut the abdominal wall with a pair of scissors and cut towards the sternum. Lift  the scissor as you cut to prevent cutting of the heart bloods vessels or other internal organs.

4. Cut through the pectoral girdle to expose the heart in the pericardial sac.

 5. Carefully remove the pericardial sac.

 6. Cut any connective tissue attachments (not the vessels around the atria) so that the heart beats freely.

 7. Using forceps to grasp the apex of the ventricle and push the point of the ‘J’-hook into  the apex of the ventricle. Push the hook through the ventricle wall until the bend of the  hook is inside the heart.

 8. Connect the thread from the frog heart to the force transducer S-hook Use a square knot  and tie it twice to make sure it won’t come loosen when the heart contracts.

 9. Position the frog so the thread from the heart is vertical. If it is pulling at an angle much  of the contraction of the frog heart will not be observed.

10. Add ringer solution drop by drop on the heart during the experiment to avoid desiccation.

 

Heart constantly beats during lifetime under nervous control to pump blood into blood vessels. Contraction of heart is called systole.

 The cardiac cycle consists of atrial systole and diastole followed by ventricular systole and diastole. These are the events, which take place in one complete heartbeat