Dermatology SLA 4

Question 1

What are the three layers of skin?

Answer 1

Epidermis
dermis
hypodermis

Question 2

What are the layers of the epidermis?

Answer 2

Stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale

Question 3

What are the three regions of the dermis?

Answer 3

papillary
reticular
dermal papillae- (versus retes ridges on the epidermis- basal layer)

Question 4

What are the functions of the epidermis?

Answer 4

-The epidermis prevents water loss, prevents entry of bacteria and parasites and it also synthesised keratin

Question 5

What cells are the different layers of the epidermis made of and what are their functions?

Answer 5

Stratum corneum- squames cells- this is thicker on the soles of feet and palms
stratum lucidum- only on thick skin.
stratum granulosum-this has stratified squamous cells- tonofibrils are produced here by lamellar granules- which gather tonofilaments together
- stratum spinosum - cuboidal epithelial cells - produces lamellar bodies
stratum basale - columnar epithelial cells- contains melanocytes- which produces melanin. This is where there is production of tonofilaments. and has a constant production of keratonicytes- which divide continuously

Question 6

Describe the process of keratin synthesis.

Answer 6

1. At the stratum basale- there are many keratinocyes which are constantly dividing these produce tonofilaments
2. At the stratum spinosum- there is the production of lamellar bodies. contain langerhans cells
3. At the stratum granulosum the lamellar granules gather tonofilaments together to form tonofibrils.
   4.As you move up the layers of the epidermis- the PH decreases- allowing desquamation to occur

Question 7

What is the pathophysiology of psoriasis (mild and severe)?

Answer 7

Keratin usually takes 28-40 days for transit- in psoriasis the transit time of keratin is severely reduced- so it only takes 2-3 days in severe or in mild 7-8 days

Question 8

What is hyperkeratosis?

Answer 8

This is when there is excessive keratin put on the surface of the skin- more obvious on the soles of the feet and palm of the hand

Question 9

What are the fitzpatrick skin types?

Answer 9

Type 1 -pale skin, pale eyes and hair- ALWAYS TANS, NEVER TANS
Type 2- usually burns, rarely tans
Type 3- may burn, usually tans
Type 4- rarely burns- tans easily
Type 5 - rarely burns- tans darkly
Type 6- always tans never burns

Question 10

What are the key differences between thick (non hairy) and thin (hairy) skin?

Answer 10

Thick (non-hairy)- no arrector pilli muscles, no sebaceous glands,pronounced ridges, regular shaped dermal papillae, has stratum lucidum
Thin (hairy)- has arrector pilli muscles, sebaceous glands, smaller ridges, no stratum lucidum

Question 11

What are the three types of hair?

Answer 11

Vellous- covers fetus at birth
lanugo-replaces lanugo
terminal- dark hair at axillae, groin

Question 12

What are the functions of hair?

Answer 12

sexual attraction
thermoregulation
sensation- root hair plexus- this detects the vibration in the hair shaft

Question 13

What are the mechanoreceptors in the skin?

Answer 13

End bulbs- these are thermoreceptors
tactile discs - meissner(hairy skin) merkel (non-hairy)- detect flickering and tapping
noiciceptors- detect pain
Pacinian corpuscle- this detects vibration
ruffinis complex-this detects tissue stretch and joint movement
root hair plexus- vibration in root hair shaft

Question 14

What are the different components of nails?

Answer 14

lunula
cuticle
eponychium
nail bed
nail matrix