The amount of food energy (calories) a person requires varies with body weight, age, sex, activity level, and natural body efficiency.
Learning Goal 1b
Regular exercise is important to maintain a healthy heart/lung system, good muscle tone, and bone strength.
Learning Goal 2
Toxic substances, some dietary habits, and some personal behavior may be bad for one's health. Some effects show up right away, others years later. Avoiding toxic substances, such as tobacco, and changing dietary habits increase the chance of living longer.
Learning Goal 3
Viruses, bacteria, fungi, and parasites may infect the human body and interfere with normal body functions. A person can catch a cold many times because there are many varieties of cold viruses that cause similar symptoms.
Learning Goal 4
White blood cells engulf invaders or produce antibodies that attack them or mark them for killing by other white cells. The antibodies produced will remain and can fight off subsequent invaders of the same kind.
Learning Goal 5
The environment may contain dangerous levels of substances that are harmful to human beings. Therefore, the good health of individuals requires monitoring the soil, air, and water and taking steps to make them safe.
Learning Goal 6
Specific kinds of germs cause specific diseases.
Learning Goal 7
Vaccines induce the body to build immunity to a disease without actually causing the disease itself.