Toxic responses of the skin

Question 1

Which of the following statements is FALSe regarding skin histology?

a. Blood supply to the epidermis originates in the epidermal-dermal junction
b. Melanin is made and stored by melanocytes
c. The stratum corneum is made up of non-viable cells
d. It takes approx. 2 weeks for cells to be sloughed off from the stratum corneum
e. Stem cells in the basal layer replenish the keratinocytes of the layers of the epidermis

Answer 1

b. Melanin is made and stored by melanocytes

Question 2

Transdermal drug delivery does NOT:

a. prevent drug exposure to low pH
b. avoid first-pass metabolism
c. provide steady infusion over an extended period of time
c. avoid large variation in drug plasma concentration
e. increase safety of drug delivery

Answer 2

e. increase safety of drug delivery

Question 3

Irritant and contact dermatitis are marked by all of the following characteristics except:

a. softness
b. erythema
c. flaking
d. induration
e. blistering

Answer 3

a. softness

Question 4

Nickel is a common cause of allergic contact dermatitis, which is which type of hypersensitivity reaction

a. type I
b. type II
c. type III
d. type IV
e. type V

Answer 4

d. type IV

Question 5

All of the following statements regarding phototoxicology are true EXCEPT:

a. Melanin is primarily responsible for the absorption of UV-B radiation
b. UV-A is the most effective at causing sunburn in humans
c. IL-1 release is responsible for systemic symptoms associated with sunburn
d. Melanin darkening is a common response to UV exposure
e. UV radiation exposure causes thickening of the stratum corneum

Answer 5

b. UV-A is the most effective at causing sunburn in humans

Question 6

Photoallergies:

a. represent a form of type III hypersensitivity reaction
b. can occur without exposure to UV radiation
c. are hapten-mediated
d. cannot be tested for as contact dermatitis allergies can
e. often occur on first exposure

Answer 6

c. are hapten-mediated

Question 7

Diffusion through the epidermis would occur most slowly across skin at which of the following locations?

a. palm
b. forehead
c. scrotum
d. foot sole
e. abdomen

Answer 7

d. foot sole

Question 8

Which of the following statements regarding photosensitivity is FALSE?

a. Porphyrias cause light sensitivity because of the lack of heme synthesis
b. Lupus patients are unable to repair damage caused by UV light
c. Chronic phototoxic responses often result in hyperpigmentation
d. Photoallergy represents a type IV hypersensitivity reaction
e. UV radiation causes cycloadducts between pyrimidine bases

Answer 8

c. Chronic phototoxic responses often result in hyperpigmentation

Question 9

Acne is caused by all of the following EXCEPT:

a. clogged sebaceous glands
b. hormones
c. viruses
d. genetics
e. environmental factors

Answer 9

c. viruses

Question 10

All of the following statements regarding urticaria are true EXCEPT:

a. Urticaria is a delayed-type hypersensitivity reaction
b. Hives are mediated partly by histamine release from mast cells
c. Latex is a common chemical cause of urticaria
d. Select foods have been reported to elicit contact urticaria
e. Urticaria is mediated by IgE antibodies

Answer 10

a. Urticaria is a delayed-type hypersensitivity reaction