Organisms reproduce to ensure the continued survival of their respective species. For humans, our ability to produce offspring and contribute to genetic variability in the world is made possible by our body's reproductive system. In "The Reproductive System", learn how the development of the reproductive systems in both males and females depends on the delicate and coordinated balance of genetic makeup, hormones, and the nervous system. Also examined in this full-color title are the reproductive systems of males and females, and how the body develops from conception through puberty and into maturity.
The human body is an incredibly complex and amazing structure. At best, it is a source of strength, beauty, and wonder. We can compare the healthy body to a well-designed machine whose parts work smoothly together. We can also compare it to a symphony orchestra in which each instrument has a different part to play. When all of the musicians play together, they produce beautiful music.
From a purely physical standpoint, our bodies are made mainly of water.We are also made of many minerals, including calcium, phosphorous, potassium, sulfur, sodium, chlorine, magnesium, and iron. In order of size, the elements of the body are organized into cells, tissues, and organs. Related organs are combined into systems, including the musculoskeletal, cardiovascular, nervous, respiratory, gastrointestinal, endocrine, and reproductive systems.