Basic structure and function of skin

Question 1

Six main functions of normal skin

Answer 1

1. Protective barrier against environmental insults
2. Thermoregulation
3. Sensation
4. Vitamin D synthesis
5. Immunosurveillance
6. Cosmesis/social interaction

Question 2

Epidermis and appendages are derived from the…

Answer 2

ectoderm

Question 3

Dermis is derived from the…

Answer 3

mesoderm

Question 4

Principle cell type of the epidermis and it’s function

Answer 4

Keratinocyte- produces protective keratin

Question 5

Functions of:

a) Langerhans cells
b) Melanocytes
c) Merkel cells

Answer 5

a) Antigen presenting cells of the skin
b) production of melanin for UV protection
c) mechanoreceptors for light touch sensation

Question 6

Four layers of keratinocytes in the epidermis from deep –> superficial and their function

Answer 6

Basal- actively dividing cells
Prickle cells- differentiating cells
Granular cells- secretion of lipid into intercellular spaces
Stratum corneum- dead keratinocytes

Question 7

Three main types of hair?

Answer 7

Lanugo-fine foetal hair
Vellus- fine short hair on all body surfaces
Terminal hair- coarse long hair on scalp, eyebrows etc

Question 8

Growth cycle of an individual hair?

Answer 8

Anagen (growing)- 85% of all hairs at any given time
Catagen (short regressing phase)
Telogen (resting/shedding phase)

Question 9

What is

a) nail matrix
b) lunula
c) cuticle

Answer 9

a) structure which gives rise to the nail plate by cell division
b) the white half-moon structure at nail base (the underlying nail matrix)
c) extension of the stratum corneum from the proximal nail fold onto the nail plate

Question 10

Sebaceous glands become active at … and are responsible for secreting….?

Answer 10

Puberty, sebum (waterproofing/antibacterial substance)

Question 11

Two types of sweat glands and difference between them?

Answer 11

Eccrine- all over body

Apocrine- axilla, genitalia, anus and external auditory canal. Only function from puberty onwards