Maintaining health

Health is more than not being sick. It has three connected parts: physical health (how your body works), mental and emotional health (how you think, feel, and handle stress), and social health (your relationships). Each part affects the others. Now that you know how the body systems work, you can see why everyday habits matter so much.

Nutrition gives your body the materials it needs. Carbohydrates supply energy, proteins build and repair tissue, fats store energy and form cell membranes, and vitamins and minerals in small amounts keep many processes running. Water is needed for blood, digestion, and the kidneys. A balanced diet includes fruits, vegetables, whole grains, protein foods, and dairy or fortified alternatives, with limited added sugar and salt. You have already met several examples: calcium and vitamin D for bones, iron for hemoglobin, and fiber for the large intestine.

Physical activity is recommended for children and teens at about 60 minutes a day, most of it moderate to vigorous. It strengthens muscles and bones, helps the heart and lungs work efficiently, and improves sleep and mood. Sleep is when the body repairs tissue, releases growth hormone, and stores memories. Children ages 6 to 12 need about 9 to 12 hours a night, and teens about 8 to 10.

Hygiene prevents infection. Wash your hands with soap for 20 seconds, cover coughs and sneezes, and keep cuts clean. Brushing and flossing protect teeth and gums. Sun protection, with sunscreen, hats, and shade, protects the skin.

Some substances harm developing bodies. Tobacco and vaping products contain nicotine, which is addictive and affects the brain, which keeps developing until the mid-20s. Smoking damages the cilia and alveoli of the lungs. Alcohol and other drugs harm the brain, liver, and other organs.

Mental health matters just as much. Everyone feels stress, and healthy ways to cope include exercise, sleep, time with friends, and talking with a trusted adult. If sadness, worry, or anger do not go away, getting help from a counselor or doctor is a sign of strength. Regular checkups, dental visits, and vaccines also help find or prevent problems early.

Common mistakes: thinking that habits do not matter while you are young, when the bone and habits you build now last for decades, and thinking supplements can replace a balanced diet. Next lesson: common diseases and how they are prevented.