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?

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.

Are these substances polar or nonpolar?

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.

Predict whether or not these substances are likely to be absorbed by the epidermis.

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.

Predict the effectiveness of the creams.

Would a mild second-degree burn be likely to heal by regeneration or fibrosis? Would the same type of healing take place in a third-degree burn that involved muscle tissue? Why or why not?

Explain why the skin is an organ.

Which of the following correctly describes the structure of the skin?

a. It consists of the superficial epidermis, middle dermis, and deep hypodermis.

b. It consists of the superficial epidermis and deep dermis.

c. It consists of the superficial dermis and deep epidermis.

d. It consists of the superficial dermis and deep hypodermis.

Which of the following is not a function of the integument?

a. Protection from mechanical trauma

b. Thermoregulation

c. Protection from acid-base imbalances

d. Vitamin D synthesis

Explain what happens to dermal blood vessels when heat needs to be conserved (i.e., due to a cold environment).

Number the strata of thick skin epidermis from deepest (1) to most superficial (5). 

____Stratum spinosum     

____Stratum corneum     

____Stratum basale     

____Stratum lucidum     

____Stratum granulosum

Keratinocytes in the superficial strata of the epidermis die because:

a. They are too far away from the blood supply in the dermis.

b. They are surrounded by a lipid-based substance that makes them more permeable to water.

c. They do not die.

d. No keratinocytes in the epidermis are alive.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Melanocytes account for the bulk of the epidermis.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Keratinocytes begin life in the stratum corneum and gradually are pushed into the stratum basale.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Dendritic cells are phagocytes of the immune system that protect the skin and deeper tissues from invasion by pathogens.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Merkel cells produce the pigment melanin.

Which of the following statements is false?

a. Thin skin lacks the stratum lucidum, whereas thick skin has all five epidermal layers.

b. Thick skin is located on the palms, the palmar surfaces of the fingers, the soles of the feet, and the plantar surface of the toes, whereas thin skin is located everywhere else.

c. Thick skin has numerous hairs, whereas thin skin lacks hairs.

d. Thin skin has a thin stratum corneum, and the other layers are thinner than what we find in thick skin.

What are the functions of the dermal papillae?

Epidermal ridges are created by:

a. The epidermal papillae

b. Mounds of papillary dermis arranged into dermal ridges

c. Gaps between collagen bundles in the reticular layer

d. Tight binding of the reticular layer to deeper structures

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The primary skin pigment is melanin, which is derived from the amino acid tyrosine.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Melanin is produced by melanocytes and covers the nuclei of neighboring dendritic cells.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Carotene is a brown-black pigment that accumulates in the stratum corneum.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Increased amounts of blood flowing through the dermis lead to pallor in the skin.