CLEAN : Polls open in Maryland US presidential primary

The video provides a brief introduction to the heart, focusing on its basic function and importance in the human body.

What is the initial focus of the video tutorial?

• A summary of the entire video

• An introduction to the main concept

• The conclusion of the topic

• A detailed analysis of the subject

What is the main topic mentioned in the video?

• Heart

• Liver

• Brain

• Lungs