Which ECG wave is represented by the letter “A”.  

Name the cavity labeled “E”  

Identify the structure at the tip of the blue arrows

Identify the blood vessels indicated by the arrows labeled “F”.

Identify the tapered region of the heart surrounded by the black circle.

Identify the histological structure at the tip of the arrow labeled “A”

Identify the vein indicated by the arrow labeled “A”  

Identify the blood vessels at the tip of the black arrow.    

What type of tissue is found in the area labeled “A”

Which of these structures is called the pacemaker of the heart? Answer the question by writing down the letter on the picture corresponding to the question asked.