HUMAN BIOLOGY 



body. Here, also, are the lungs, which take in oxygen and 

 give it to the blood, and which remove carbon dioxid, water, 

 and other waste matters from the blood. Below the dia- 

 phragm are the stomach and the intestines, the liver and the 



spinal cord 

 (composed of 

 nerve cells 

 and nerve 

 fibers) 



spinal column 

 (composed of 

 vertebrae and 

 cartilage) 



chest cavity 



diaphragm 



abdominal cavity 



FIG. 1. Longitudinal section of trunk (side view). 



pancreas, all of which help to change our food into liquid 

 form ready to be used by the body. All these and other 

 parts of the body are called organs. An organ is a part of a 

 living body that has some, special work to do; this special work 

 is called its function. Our hands, for example, are organs 



