Organs and organ systems are composed of cells and help to provide all cells with basic needs.
Learning Goal 2
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.
Learning Goal 3
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 eliminate the carbon dioxide produced. The urinary system disposes of dissolved waste molecules, the intestinal tract removes solid wastes, and the skin and lungs aid in the transfer of thermal energy from the body. The circulatory system moves all these substances to or from cells where they are needed or produced, responding to changing demands.
Learning Goal 4
Specialized cells and the molecules they produce identify and destroy microbes that get inside the body.
Learning Goal 5
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.
Learning Goal 6
Interactions among the senses, nerves, and brain make possible the learning that enables human beings to predict, analyze, and respond to changes in their environment.