CLT Skin Anatomy & Physiology 3 — Questions and Answers
Question 1: What is the approximate pH range of healthy, intact skin surface?
- 3.0–4.0
- 4.5–5.5 (Correct answer)
- 6.5–7.0
- 7.0–7.4
Correct answer: 4.5–5.5
Normal skin has a slightly acidic pH of 4.5–5.5, forming the 'acid mantle' that inhibits microbial growth and maintains barrier function.
Question 2: Melanin is synthesized from which amino acid precursor?
- Tryptophan
- Phenylalanine
- Tyrosine (Correct answer)
- Histidine
Correct answer: Tyrosine
Melanin biosynthesis begins with tyrosine, which is converted to DOPA and then dopaquinone by the enzyme tyrosinase in melanosomes.
Question 3: Which cells in the skin are responsible for the immunological surveillance and antigen presentation?
- Merkel cells
- Langerhans cells (Correct answer)
- Fibroblasts
- Mast cells
Correct answer: Langerhans cells
Langerhans cells are dendritic antigen-presenting cells in the epidermis that capture antigens and present them to T-lymphocytes, playing a key immune role.
Question 4: The stratum granulosum is named for the granules it contains, which are primarily:
- Melanosomes
- Lamellar bodies and keratohyalin granules (Correct answer)
- Lipid droplets
- Glycogen stores
Correct answer: Lamellar bodies and keratohyalin granules
The stratum granulosum contains keratohyalin granules (which form the keratin matrix) and lamellar bodies that release lipids to form the skin barrier.
Question 5: In laser treatments, post-inflammatory hyperpigmentation (PIH) is most likely to occur in patients with:
- Fitzpatrick Type I–II skin
- Fitzpatrick Type IV–VI skin (Correct answer)
- Dry, dehydrated skin
- Thin, atrophic skin
Correct answer: Fitzpatrick Type IV–VI skin
Darker Fitzpatrick skin types (IV–VI) have more active melanocytes that are prone to overproducing melanin in response to thermal injury, causing PIH.
Question 6: The subcutaneous layer (hypodermis) is composed mainly of:
- Dense irregular connective tissue
- Adipose tissue and loose connective tissue (Correct answer)
- Smooth muscle fibers
- Stratified squamous epithelium
Correct answer: Adipose tissue and loose connective tissue
The hypodermis consists primarily of adipose (fat) cells and loose connective tissue, providing insulation, energy storage, and cushioning.
Question 7: Which sensory receptor in the skin is specifically associated with detecting light touch and located in dermal papillae?
- Pacinian corpuscle
- Ruffini ending
- Meissner's corpuscle (Correct answer)
- Free nerve ending
Correct answer: Meissner's corpuscle
Meissner's corpuscles are encapsulated mechanoreceptors located in dermal papillae of fingertips and lips, specialized for detecting light touch and texture.
CLT Skin Anatomy & Physiology 3
What is the approximate pH range of healthy, intact skin surface?