Structure and Function of the skin Flashcards
What is the largest organ of the body?
The skin (duh)
What are the two layers of the skin?
Epidermis
Dermis
What is more superficial, the epidermis or the dermis?
The Epidermis
What is the epidermis made of?
Stratified squamous epithelium
Embryologically, what kind of cells does the epidermis arise from?
Ectoderm cells
How thick is the epidermis?
1.5mm
True or False, 95% of the cells in the epidermis are melanocytes?
FALSE
95% are keratinocytes
What are the four layers of the Epidermis?
Keratin layer
Granular layer
Prickle cell layer
Basal layer
What other cells are found in the epidermis?
Melanocytes
Langerhans cells
Merkel cells
Where is the dermis in relation to the epidermis?
Beneath it
What is the dermis made of?
Connective tissue
What is the dermis formed from (embryologically)?
Mesoderm
How many layers are there to the foetal skin at 4 weeks?
3
Periderm
Basal layer
Dermis
Name 2 Skin appendages:
Hair follicles
Melanocytes
What is the function of the arrector pili?
Controls temperature
What are the lines of skin development known as?
Blaschko’s lines
What three factors control the regulation of epidermal turnover?
Growth factors
Cell death
Hormones
How long does the regeneration of the epidermis take in healthy skin?
28days
How long does the regeneration of the epidermis take in psoriasis patient’s?
5days
How thick is the basal layer?
One cell thick
Are there intermediate filaments in the basal layer?
Yes, lots of keratin
Is the basal layer metabolically active?
Yes
Why are there desmosomes in the prickle cell layer?
Because the cells are constantly vibrating and moving upwards so do not stay together
What happens to the prickle cell layer in psoriasis?
It thickens
How thick is the granular layer?
2-3 cells thick
What to the large keratohyalin granules in the granular cell layer contain?
Filaggrin and Involucrin
Where is the origin of the cornified envelope?
The granular cell layer
What is the keratin layer made up of?
Corneocytes
What are the 4 different types of epidermal cells?
Keratinocytes
Melanocytes
Langerhan’s cells
Merkel cells
Where do melanocytes come from?
Neural crest
Where are melanocytes found?
Basal layer and above
What kind of cell are melanocytes?
Pigment producting dendritic cells
What organelles do melanocytes contain?
Melanosomes
What are melanosomes responsible for?
Converting tyrosine to melanin
Eumelanin (brown or black)
Phaeomelanin (red or yellow)
T/F melanin absorbs light?
True
What stimulates the production of melanin?
UV light
Hormones
Where do langerhan’s cells come from?
Mesenchyme (bone marrow)
Where are langerhan’s cells found?
Prickle cell layer
Dermis
Lymph noders
What type of cell are Langerhan’s cells?
Antigen presenting cells
What type of cells are Merkel cells?
Basal cells
Mechanoreceptors