MENU

Biosphere
- Syllabus
- Course Calendar
- Scientific Method
- Alive
- Origins
- Water
- Biomes
- Food Webs
- Biodiversity
- Population Growth

Cells

Early Life

Invertebrates

Vertebrates

Humans

Plants

Integumentary System

Introduction to this section:

Reading:
Hawaii to ban certain sunscreens harmful to coral reefs
Skin cancer-detecting device wins 2017 James Dyson award
'Digital skin' activates brain cells
No safe way to suntan, new NICE guidance warns

Figure 1: Layers of Human Skin

Video 1: Integumentary System (7:31)

Video 2: Why do we have to wear sunscreen? (5:01)

Study Guide (Transcripts/Summaries):
Our skin is formally known as the integumentary system. Skin has 3 main layers: the epidermis, the dermis, and the hypodermis or subcutaneous layer. The functions of skin are protection, sensation, thermoregulation, and synthesis of Vitamin D. The epidermis has four layers (you don’t need to know their names). This is where new skin cells are created by mitosis. As new cells are formed, the older cells begin to die and are pushed to the surface. The epidermis is also the location of melanocytes that are responsible for skin tones. The dermis is below the epidermis. This layer contains capillaries, gland cells, and nerve receptors. The bottom layer is the hypodermis or subcutaneous layer. It consists of stem cells, connective tissue, reticular fibers, adipocytes, mesenchymal cells, elastic fibers, collagen fibers, fibroblasts, and macrophages.

Sunscreen shields the body from ultraviolet rays. Two wavelengths of concern are called UVA and UVB. UVB causes skin to burn. UVA is less well understood but has an effect on the tanning response, carcinogenesis, and aging. Two types of sunscreen are physical and chemical blockers. Physical blockers are zinc oxide and titanium dioxide that reflect the sun’s rays. Chemical blockers absorb the sun’s rays. SPF stands for Sunburn Protection Factor a measure of the level of protection that sunscreen will provide to UVB rays before skin begins to burn. Sunscreen also helps to protect against the effects of UVA rays.

Sources:
Figure 1: Layers of Human Skin from: CK-12 Biology (say thanks), http://www.ck12.org/book/CK-12-Biology-Concepts/, Figure 13.24
Video 1: Integumentary System, https://www.youtube.com/watch?v=z5VnOS9Ke3g
Video 2: Why do we have to wear sunscreen? - Kevin P. Boyd, https://www.youtube.com/watch?v=ZSJITdsTze0