Women stop releasing eggs and, hence, can no longer reproduce. The length and quality of human life are influenced by many factors, including sanitation, diet, medical care, sex, genes, environmental conditions, and personal health behaviors. The FOSS program does not include a component developing concepts related to Human Identity and Human Development at this level. For the body to use food for energy and building materials, the food must first be digested into molecules that are absorbed and transported to cells. To burn food for the release of energy stored in it, oxygen must be supplied to cells, and carbon dioxide removed.
Lungs take in oxygen for the combustion of food, and they eliminate the carbon dioxide produced.
The urinary system disposes of dissolved waste molecules, the intestinal tract removes solid wastes, and the skin and lungs rid the body of heat energy. The circulatory system moves all these substances to or from cells where they are needed or produced, responding to changing demands. Specialized cells and the molecules they produce identify and destroy microbes that get inside the body. Hormones are chemicals from glands that affect other body parts. They are involved in helping the body respond to danger and in regulating human growth, development, and reproduction.