The Skin

Question 1

What are the 2 major classes of skin?

Answer 1

Hirsute - thin, hairy skin which covers most the body
Glabrous - palms, soles and flexor surfaces of digits

Question 2

What are the 3 layers of the skin?

Answer 2

Epidermis
Dermis
Subcutaneous layer

Question 3

What are the 5 layers of the epidermis?

Answer 3

Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum (most superficial)

Question 4

What happens to the skin with aging?

Answer 4

Both skin and mucous membranes become thin and fragile. Dermis becomes thinner and subcutaneous tissue is diminished
Fewer capillaries and cell proliferation is decreased, slower wound healing
Number of sensory receptors in skin and mucosa decline
Skin becomes dry and wrinkles as elastic fibres and reduces
Collagen fibres become less flexible
Melanocytes decrease causing grey hair & skin

Question 5

What is the skin like in a developing foetus?

Answer 5

Epidermis develops from a single layer of ectoderm then other layers are added
Brown adipose tissue (BAT) develops from 17 - 20 weeks gestation
>18 weeks, foetus is covered in white creamy substance called vernix caseosa
By 20 weeks foetus is covered in lanugo
36 weeks - lanugo is shed

Question 6

What are the functions of the skin?

Answer 6

Protection
Regulation of body temperature
Formation of vit D
Cutaneous sensation
Excretion
Absorption
Movement and growth

Question 7

How is the skin important to health?

Answer 7

Acts as a barrier to protect the body from invasion of bacteria

Question 8

What is keratinisation?

Answer 8

Stem cells divide to produce keratinocytes as they are pushed to the surface, they fill with keratin
Keratinisation is replacement of cell contents with the protein keratin