A class was studying human body systems. The students learned about a system that moved oxygen to the cells and contained structures that help the body fight
infections.
The class was studying the -
muscular system
digestive system
circulatory system
endocrine system
CLEAR ALL

The circulatory system consists of the heart and blood vessels which encompass all of the arteries, veins, and capillaries. The arteries carry oxygenated blood away from the heart, and veins return deoxygenated blood back to the heart. The main purpose of the circulatory system is to transport blood, oxygen, nutrients, and hormones to and from different cells and tissues throughout the body. This system works hand-in-hand with the respiratory system to facilitate the exchange of oxygen and carbon dioxide within the blood per the alveoli in the lungs. It is also very important for the removal of wastes and poisons within the body via the digestive and urinary systems.

Explanation:

when it is at an intermediate population density