Blood leaving the right ventricle enters the

The left lung is composed of how many lobes?

Identify the waste gas removed from the blood during expiration.

The wall separating the left side of the heart from the right side is the

Which structures prevent heart valves from being forced backward into the wrong chamber? 

Which structure holds the chordae tendineae to the interior walls of the heart?

The SA node is located in the

What structure helps to prevent food from entering the sinus cavity during swallowing?

The trachea divides into two branches called the

The cartilaginous rings which make up the trachea are