The pre-caval veins collect blood from

$A$ heart murmur indicates a defective

In humans,blood passes from the post caval vein into the diastolic right atrium of the heart because of:

In a patient,the cardiac pacemaker stops functioning. The doctor decides to implant an artificial pacemaker. Its function is similar to which of the following?

State the location of the $SA$ node and the $AV$ node.

Heart sounds can be heard using a: