Skin Structure & Function

Question 1

Epidermis tissue type

Answer 1

Stratified squamous epithelium

Question 2

Dermis tissue type

Answer 2

Connective tissue

Question 3

Layers of the epidermis

Answer 3

Superficial to deep - 
Keratin layer 
Granular layer 
Prickle cell layer 
Basal layer 
(then dermis)

Question 4

rete ridges

Answer 4

downward projections of the epidermis down into the dermis

Question 5

Blaschko’s lines

Answer 5

lines of normal cell development in the skin - not seen normally.
Presence indicates a developmental growth pattern of skin problem

Question 6

What composes 95% of the epidermis

Answer 6

Keratinocytes

Question 7

Why is there continuous regeneration of the epidermis

Answer 7

Keratinocytes migrate from the basement membrane of the epidermis

Question 8

How long does the process of keratinocyte migration normally take

Answer 8

around 28 days

Question 9

How long does the process of keratinocyte migration take in psoriasis

Answer 9

45 days

Question 10

In what layer of the epidermis can intra-epidermal blistering occur

Answer 10

Prickle cell layer -

lots of desmosomes (connections) that are burst apart by hydrostatic pressure

Question 11

What layer of the epidermis is the origin of the ‘cornified envelope’

Answer 11

Upper cells of the granular layer - stratum corneum

lose their nuclei and become surrounded by tough envelope of proteins

Question 12

what are corneocytes

Answer 12

terminally differentiated keratinocytes that are non-nucleated

Question 13

what common skin complaint affects keratinocytes

Answer 13

Warts - HPV 4+11

Question 14

why are children more susceptible to warts

Answer 14

cornified envelope hasn’t formed properly

Question 15

Other epidermal cells apart from keratinocytes

Answer 15

melanocytes
langerhans cells
merkel cells

Question 16

What are skin appendages

Answer 16

hair follicles
sebaceous glands
sweat glands

Question 17

what are melanocytes

Answer 17

melanin-producing neural-crest derived cells

pigment-producing dendritic cells

Question 18

What layer of epidermis are melanocytes found

Answer 18

basal layer

Question 19

Vitiligo

Answer 19

autoimmune disease with loss of melanocytes

Question 20

Albinism

Answer 20

genetic partial loss of pigment production

Question 21

Nelson’s syndrome

Answer 21

Clinical sign for presence of a pituitary tumour - melanin stimulating hormone produced in excess by pituitary

Question 22

What layer of epidermis are Langerhan’s cells found in

Answer 22

Prickle cell layer (suprabasal)

also dermis and lymph nodes

Question 23

What are Langerhan’s cells

Answer 23

main skin resident immune cell

antigen-presenting - pick up antigen in skin and circulate to lymph node

Question 24

Characteristic of Langerhan’s cells

Answer 24

Birbeck granules

Question 25

What are merkel cells

Answer 25

mechanoreceptors found in skin (mostly palms and soles) responsible for light touch sensation

Question 26

What layer of epidermis are merkel cells found in

Answer 26

basal layer

Question 27

what are hair follicles also known as

Answer 27

pilosebaceous unit (adjacent sebaceous gland)

Question 28

dermal papillae definition

Answer 28

any small elevation in the dermis that indent the inner surface of the epidermis

Question 29

Label the different parts of the pilosebaceous unit

Answer 29

(be able to do)

Question 30

phases of growth of hair follicles

Answer 30

Anagen = growing (3-7yr)

Catagen = involuting (3-4wks)

Telogen = resting (shedding) (each day 50-100 <1%)

Question 31

Label the different parts of the nail unit

Answer 31

(be able to do)

Question 32

Hyponychium of the nail

Answer 32

secures the free nail edge

Question 33

Structure of the Dermo-Epidermal junction

Answer 33

From superficial to deep -

Hemidesmosomes - at basal cell layer of epidermis 
Lamina lucida 
Lamina densa 
Sub lamina densa zone 
(then dermis)

Question 34

Inherited conditions of the DEJ

Answer 34

Epidermolysis bullosa - mutation of one of the proteins in the DEJ

Question 35

Acquired conditions of the DEJ

Answer 35

Pemphigus
Pemphigoid
Dermatitis herpetiformis
- autoantibodies to proteins in the DEJ

Question 36

What are the different components of the dermis

Answer 36

Cells:
fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells

Fibres:
collagen, elastin

Ground substance:
jelly like mass

Blood vessels, lymphatics, nerves

Question 37

Role of fibroblasts in dermis

Answer 37

Collagen secretion

Question 38

Role of macrophages in dermis

Answer 38

Antigen presentation

Question 39

Role of Langerhans cells in dermis

Answer 39

Antigen presentation

Question 40

Role of mast cells in dermis

Answer 40

Chemical messengers

Question 41

How do blood vessels in the dermis appear

Answer 41

as horizontal plexuses

Question 42

role of lymphatic vessels in dermis

Answer 42

continual drainage of plasma proteins, extravsculated cells and excess interstitial fluid

Question 43

Specialised nerve receptors in the dermis

Answer 43

Pancinian receptors - pressure receptors
(nearer bottom of dermis)

Meissners corpuscles - vibration receptors
(nearer top of dermis)

Question 44

Different types of skin glands

Answer 44

Sebaceous glands
Apocrine glands
Eccrine glands

Question 45

What are sebaceous glands

Answer 45

exocrine glands that secrete oily sebum
present on face and chest mostly
hormone sensitive
inactive until puberty

Question 46

What are apocrine glands

Answer 46

develop as part of pilosebaceous unit (coiled side part on histology)
found mostly in armpits, areola of nipples
androgen dependent sweat glands

Question 47

What are eccrine glands

Answer 47

common sweat gland
found throughout skin except mucosal surfaces
mostly palms/soles to aid grip

Question 48

Main metabolic roles of skin

Answer 48

vitamin D metabolism

thyroid hormone metabolism (T4 to T3)