Skin

Question 1

Describe initial embryology skin

Answer 1

one layer of ectodermal cells overlying a dermis ( loosely arranged mesenchymal cells )
ectoderm and mesoderm

Question 2

Describe the embryology of the epidermis

Answer 2

-ectoderm divides in two - basal cell layer and outer layer periderm
-between them is stratum intermedium
-give rise to different layers of the epidermis
-later melanocytes and langerhans

Question 3

Describe the embryology of the dermis

Answer 3

-increase thickness and no of fibres — -mesenchymal cells to fibroblasts
-collagen then elastin -connective tissue
-ground substance allows this
-nerve and bv developments
- histocytes and dermal melanocytes

Question 4

Describe subcutis embryological development

Answer 4

lipocytes start to develop

Question 5

Embryology of hair

Answer 5

-epidermal basal cells proliferate into dermis - hair bud
- aggregation of mesenchymal cells ( dermal papilla ) project into hair bud
-epidermal cells grow around papilla creating hair bulb from which the hair grows

Question 6

components of epidermis

Answer 6

-keratinocytes
-keratins filaments
-desmosomes
-hemidesmosomes
-melanocytes
-langerhans ( APC )

Question 7

What are keratins ?

Answer 7

intermediate -filament forming proteins that provide mechanical support
cr - pamopalmar hyperkeratosis

Question 8

what are desmosomes ?

Answer 8

anchor keratinocytes to each other
cr- pemphigus foliaceus

Question 9

What are hemidesmosomes ?

Answer 9

anchor epidermis to the dermis
cr - epidermolysis bullosa acquisita EBA

Question 10

outline the nerves in the dermis

Answer 10

sensory - respond touch , pressure , temp, pain , pruritis
mechanoreceptors - free ending , rapid adapting ( meisseners and pacinican corpuscle ) , slow adapting ( merkel cells, ruffini corpusles )

Question 11

blood supply in the dermis

Answer 11

deep dermal vascular plexus
mid-dermal vascular plexus
superficial dermal vascular plexus

Question 12

outline struc and func of sebaceous glands

Answer 12

-basal layer of germinative cells differentiate into large polygonal cells
-holocrine secretion produce sebum which lubricates hair and skin and needed for normal hair shaft separation
cr - sebaceous adenitis

Question 13

What are the 2 different sweat glands found in the dermis ?

Answer 13

epitrichial - associated with hair follicle
atrichial - not associated with hair follicle ( find in non hair areas like noise and foot pads )

Question 14

Struc and func of hairs

Answer 14

-specialised keratinised tubular structures - primary , secondary , has cortex , medulla and cuticle containing variable pigment
- insulation , signalling and physical protection

Question 15

anagen

Answer 15

growth phase
deep dermis

Question 16

telogen

Answer 16

resting phase

Question 17

Hair cycle regulation

Answer 17

-photoperiod
-temp
-hormones - thyroid , GH ( hair grow ) , oestrogen and corticosteroids (stop hair growth )
-nutrition
- drugs

Question 18

hypodermis struc and func

Answer 18

• connective tissue - fat and collagen
• energy reserve , thermogenesis and insulation , protective padding and support

Question 19

skin func

Answer 19

protective barrier
chemical barrier
normal flora inhibits infectious agents
temp reg
excretory organ
sensory organ
produce vitamin d
store nutrients
absorptive surface
blood pressure reg
photoprotection

Question 20

other factors effecting skin

Answer 20

-nutrition -protein, fatty acid , vitamins and minerals
cr zn responsive dermatois
-hormones - MSH(pigment ) , melatonin ( moutling hair growth ) , thyroid and GH ( hair growth ) , adrenal cortical hormones and oestrogen ( decrease hair growth )