circulatory system
The heart is the key organ in the circulatory system.
circulatory system diagram
It usually beats from 60 to 100 times per minute.
simple circulatory system diagram labeled
A wall called the interatrial septum divides the right and left atria.
circulatory system animation
Arteries carry blood away from the heart.
circulatory system heart
The two largest veins are the superior and inferior vena cavae.
