Structure and Function

Question 1

What are the two main layers on the skin and what are they mainly comprised of?

Answer 1

Epidermis; stratified cellular epithelium

Dermis; loose connective tissue

Question 2

What connects the dermis and the epidermis and how does this work?

Answer 2

Dermal-epidermal junction

Uses specialised proteins which stick the two layers together

Question 3

What is the sub-cutis made of?

Answer 3

Fat (adipose tissue)

Question 4

What type of cells make up 95% of the epidermis?

Answer 4

Keratinocytes

Question 5

What are the 4 epidermal cell layers?

Answer 5

Basal layer, prickle cell layer, granular layer, keratin layer

Question 6

How long does it take basal cells to migrate from the bottom to the top of the epidermis?

Answer 6

28 days

Question 7

What type of cells do melanocytes develop from?

Answer 7

Neural cells - are dendritic

Question 8

What stimulates melanin production from tyrosine?

Answer 8

UV light or hormones

Question 9

What is the disease process in vitiligo?

Answer 9

Melanocytes are attacked by T cells

Question 10

What is the purpose of Langerhans cells?

Answer 10

IMMUNE CELLS; Antigen presenting cells - circulate to lymph nodes in lymphatics

Question 11

Where are Merkel cells found and what is their function?

Answer 11

In the basal layer
Act as mechanoreceptors (detect something on the skin surface)
Are a direct extension of the brain - nerve cells

Question 12

What is the pilo-sebaceous unit comprised of and what are the functions of the parts?

Answer 12

A hair follicle (pilo) and a sebaceous gland

Sebaceous gland; secretes a waxy substance which greases the skin

Question 13

What are the phases of growth of a hair follicle?

Answer 13

Anagen (growing)
Caagen (involuting - retracting)
Telogen (resting - shedding phase)

Question 14

What is the importance of the dermal-epidermal junction?

Answer 14

To allow blood supply for oxygen/nutrients to the epidermis as it doesn’t have its own

Question 15

What fibres are present in the dermis and what are their functions?

Answer 15

Collagen (70%); strength

Elastin; elasticity (degrades with age)

Question 16

Why does the skin have so many more blood vessels than it needs? (80%)

Answer 16

For thermoregulation

Question 17

What are the three types of skin glands and their functions?

Answer 17

Eccrine (sweat glands covering the majority of the skin - concentrated under the arms and on the palms and soles)

Sebaceous (produce greasy protective substance - attached to hair follicles)

Apocrine (sweat glands under arms and surrounding genitalia)

Question 18

What are the six functions of the skin?

Answer 18

Barrier,
Thermoregulation,
Communication,
Immune defence,
Metabolism and detoxification (vit D/thyroxine),
Sensory

Question 19

What causes the sensory functions of the skin?

Answer 19

Nerve endings on the surface

Question 20

What so melanocytes look like?

Answer 20

Have a white ring surrounding them