Which of these occurs during the atrial systole?

Identify the blood vessel of the heart.

Which of the following regulates the normal activities of the heart?

To measure ECG, usually how many electrodes are connected to a patient?

Which of these are present in the plasma of a person having ‘O’ blood group?

Which of the following letters is marked incorrectly in the given diagram?

Which of the following muscles have the longest refractive period?

How much hemoglobin is normally present in 100ml of blood?