specialised tissues

Question 1

what other organ systems does skin have complex interrelationships with

Answer 1

endocrine, immune, vascular, neural

Question 2

layers of skin

Answer 2

epidermis (basement membrane), dermis, subcutis

Question 3

structures within the skin

Answer 3

pilo-sebaceous unit, sweat glands, melanocytes, Langerhans cells, desmosomes, keratinocytes, lymphatics, nerves

Question 4

structure of pilo-sebaceous unit

Answer 4

follicle, hair shaft, sebaceous gland and pilo erecti muscle

Question 5

types of sweat glands

Answer 5

apocrine: watery; eccrine: viscous, breaks down bacteria, contains pheromones

Question 6

skin functions

Answer 6

protection against injury; protection against pathogenic organisms; waterproofing and fluid conservation; thermoregulation achieved by regulation of blood flow (under sympathetic control), sweating, shivering and behaviour; protection against radiation, absorption of UV radiation and vitamin D production (deficiency causes rickets); surface for grip; sensory organ; cosmetic

Question 7

where is the epidermis derived from

Answer 7

ectoderm

Question 8

where is the epidermis

Answer 8

on skin surface

Question 9

what 4 layers are keratinocytes in within the epidermis (from deep to superficial)

Answer 9

stratum basale, spinosum, granulosum, corneum

Question 10

keratin proliferation within the epidermis

Answer 10

move up epidermis to corneum and differentiate: basal cell → prickle cell → granular cell → keratin

Question 11

cells and their location within the epidermis

Answer 11

dendritic cells: melanocytes (melanin; stratum basale); Langerhans cells (APC; spinosum); Merkel cell (sensation; stratum basale)

Question 12

what is in beyween keratinocytes

Answer 12

“glue” of lipids and proteins (incl. filaggrin)

Question 13

what is the function of the “glue”

Answer 13

barrier function to prevent infection, allergies and conditions such as eczema (caused by filaggrin gene mutation which causes palmar hyperlinearity)

Question 14

what is the basement membrane zone also known as

Answer 14

dermo-epidermal junction

Question 15

where is the basement membrane zone

Answer 15

where epidermis attaches to dermis

Question 16

what attaches the epidermis to the dermis and how is this achieved

Answer 16

hemi-desmosomes; anchor plaques and many proteins incl. tonofilaments and anchoring fibrils

Question 17

what happens if a protein is defective withing the basement membrane zone

Answer 17

genetic conditions which is repaired with scar tissue

Question 18

what causes premature death from skin cancer

Answer 18

constant inflammation

Question 19

where is the dermis derived from

Answer 19

mesoderm

Question 20

what does the dermis contain

Answer 20

supportive connective tissue: collagen, elastin and glycosaminoglycans synthesised from fibroblasts

Question 21

structure of dermis from superficial to deep

Answer 21

papillary → reticular → hypo fat layer

Question 22

what immunocompetent cells are present in the dermis

Answer 22

dermal dendritic cells

Question 23

what is the subcutaneous layer

Answer 23

connective tissue and fat

Question 24

what are melanocytes and where are they

Answer 24

dendritic cells within epidermal basal layer

Question 25

where are melanocytes derived from

Answer 25

neural crest

Question 26

where is melanin produced within melanocytes

Answer 26

melanosomes

Question 27

pathway of melanin to adjacent keratinocytes

Answer 27

melanin packaged into granules → move down dendritic processes → transferred by phagocytosis to adjacent keratinocytes

Question 28

what do melanin granules do

Answer 28

form protective cap around keratinocyte nuclei to protect DNA from UV

Question 29

what does this protective cap lead to

Answer 29

skin pigmentation

Question 30

what influences variation in racial pigmentation

Answer 30

number and size of melanosomes