The human body is a complex structure that has within it several systems that function efficiently to take care of its different needs. These are the respiratory system, the circulatory system, the digestive system, the endocrine or hormonal system, the lymphatic or immune system and so on.
The structure and workings of the human body’s systems can differ from that in other animals. For example, while insects like the fruit fly have no blood vessels (their organs float in the blood inside their bodies) they do have a heart that pumps the blood and makes it circulate from the lower part of the body to the upper parts and vice versa.
Here are some questions about the systems of the human body.
