Put the layers of the epidermis in order A- Stratum Corneus B- Stratum Basalum C- Stratum Granulosum D- Straturm Spinosum
B-D-C-A
A-B-C-D
D-B-A-C
Which of the following stratum basale cells are associated with sensory nerves?
Merkel cell
Melanocyte
Basal cell
How much of the stratum basale is made of melanocytes?
8-10%
12-16%
20-23%
Which of the following has dentritic projections?
Basal cells
Melanocytes
Merkel cells
What are produced by melanocytes?
Melanin
Melanosomes
Melanodesmosomes
Which of the following cells are actively dividing?
Basale
Langerhans
What happens to melanocytes to cause sunburn?
High UV causes melanosome overproduction
High UV causes melanocyte apoptosis
How do melanosomes work?
When exposed to UV, they form a 'cap' over the nucleus
When exposed to UV, the burst, spreading melanin throughout the cell
When exposed to UV, they destroy UV damaged proteins
Which receptor activates under UV, increasing melanosome production?
MCR1
MC2
MCR3
What enzyme converts tyrosine to dopaquinone?
Tyrosinase
Dopaquinone synthase
Which of the following are used in determining skin colour?
Red phaemelanin
Black eumelanin
Brown pheumelanin
Pink leumelanin
How many layers of cells are in the stratum spinosum?
8-10
4-6
6-8
How are cells in the stratum spinosum held together?
Desmosomes
Collagen
Myosin fibres
What is different about stratum spinosum cells compared to stratum spinosum cells?
The cytosol has shrunk somewhat
The keratin is coarser
The nucleus has begun to disintegrate
The cytosol has swelled
What is the role of langerhans cells?
Antigen presenting cells
Phagocytic cells
Sensory cells
Where are Langerhans cells found in the epidermis?
Stratum spinosum
Stratum basalum
Stratum granulosum
Where is the 'lipid glue' that holds the stratum corneum produced?
How many layers are present in the stratum granulosum?
3-5
12-15
23-24
Why does the nucleus begin to disintegrate in the stratum granulosum?
They're undergoing apoptosis
The cells are too far from the nutrient source to sustain it
What protein organises the laying down of keratin fibres?
Keratohyalin
Keratosynthase
Keratoconstructase
Why is the stratum corneum made of keratinocytes?
They're waterproof
They provide UV protection
They can be lost easily
How long does it take a cell to reach the stratum corneum?
12
14
16
What is psoriasis?
When cell turnover is too rapid (5-10 days)
When cell turnover is too slow (20-30 days)
Forms thick callouses
How many layers make up the stratum corneum?
20-35 layer
35-40
40-45
What distinguishes stratum corneum cells?
No nucleus
Held together by desmosomes
Keratin only
Shed within 3 days
How thick is the stratum lucidum?
1-3 layers
2-4 layers
4-6 layers
