Your skin is the body's largest organ and its first line of defense. It covers the outside of the body like a flexible protective shield. Skin helps keep germs, dirt, harmful chemicals, and too much sunlight from entering or damaging the body.
It also helps prevent water loss, which keeps cells and tissues working properly.
Skin has layers that work together to protect, sense, and regulate the body. The outer epidermis forms a tough barrier, while the dermis contains nerves, blood vessels, sweat glands, oil glands, and hair follicles. Nerve endings help you feel pressure, pain, heat, and cold, which helps you respond to your environment.
Sweat glands and blood vessels help control body temperature by releasing sweat and changing blood flow near the surface.
Key Facts
- Skin is the body's largest organ and acts as a barrier against germs, dirt, and injury.
- The epidermis is the outer layer and helps block pathogens and reduce water loss.
- The dermis contains nerves, blood vessels, sweat glands, oil glands, and hair follicles.
- Sweat cools the body when it evaporates from the skin surface.
- Melanin is a pigment that helps protect skin cells from ultraviolet, or UV, radiation.
- Healthy skin habits include washing gently, protecting skin from sun, drinking water, and caring for cuts.
Vocabulary
- Epidermis
- The epidermis is the thin outer layer of skin that forms a protective barrier.
- Dermis
- The dermis is the middle layer of skin that contains nerves, blood vessels, glands, and hair follicles.
- Sweat gland
- A sweat gland is a small structure in the skin that releases sweat to help cool the body.
- Melanin
- Melanin is a pigment made by skin cells that helps protect against damage from ultraviolet light.
- Nerve ending
- A nerve ending is a sensory structure in the skin that detects touch, pressure, pain, heat, or cold.
Common Mistakes to Avoid
- Thinking skin is just a covering is wrong because skin is a living organ with nerves, blood vessels, glands, and immune defenses.
- Forgetting that sweat cools by evaporation is wrong because sweat must change from liquid to vapor to carry heat away from the body.
- Assuming sun protection is only needed on hot days is wrong because UV radiation can reach skin even when the air is cool or cloudy.
- Ignoring small cuts is wrong because breaks in the skin barrier can let germs enter, so cuts should be cleaned and protected.
Practice Questions
- 1 A student spends 20 minutes outside in the morning and 35 minutes outside after lunch. How many total minutes was the student's skin exposed to outdoor sunlight?
- 2 A person drinks 6 cups of water during the school day and 3 cups after practice. If the goal is 8 cups per day, how many cups above the goal did the person drink?
- 3 Explain why skin with many nerve endings helps protect the body from injury.