Why don't you bleed when you cut your nails? Why don't you bleed when a hair is pulled?

Manufacturers of shampoos and conditioners often claim their products contain vitamins that are necessary to keep hair shafts healthy.

Do hair shafts need vitamins? (Hint: Vitamins are required for cells to carry out certain reactions.)

Why or why not? How valid are these claims?

The hair and nails are sometimes called accessory organs. Are these structures technically organs? Why or why not?

You are working in the emergency department when paramedics rush in with an unconscious patient. You notice that the patient is wearing athletic clothing and the skin on his face and elsewhere on his body is bright red. The paramedics tell you that he was picked up after collapsing during a bike race. What does the color of the patient's skin tell you about the probable cause of his illness? Explain.

After Ramon's skin came into contact with a poison ivy plant in biology lab, he developed a painful, itchy rash. However, after the skin of his colleague Cathy came into contact with snake venom in the lab, she developed no skin irritation. Poison ivy plants contain lipid-soluble oils, whereas snake venoms contain mostly water-soluble peptides. Explain why Ramon developed a rash, whereas Cathy did not.

Nguyen comes to your clinic with a mole that has recently changed in appearance. You examine the mole and note that its borders are irregular, it has a deep blue-black color, and the color is unevenly distributed throughout the mole.

What is your immediate concern? Why?

Nguyen comes to your clinic with a mole that has recently changed in appearance. You examine the mole and note that its borders are irregular, it has a deep blue-black color, and the color is unevenly distributed throughout the mole.

Nguyen tells you that she has used a tanning booth once per week for the past several years and that the tanning salon advertises it as safe. What do you tell her about the tanning salon's claim? How does any UV exposure affect keratinocytes and melanocytes? Explain.

What would happen to the skin if the oil produced by sebaceous glands was instead a polar covalent compound?

Many antiaging skin creams contain collagen and hyaluronic acid. Manufacturers claim that the collagen and hyaluronic acid applied to the surface of the skin will be absorbed into the dermis, where they will be incorporated into dermal tissue.

What are collagen and hyaluronic acid, and what are their functions?