Skin Structure and Function 1 Flashcards
What are the 5 components of skin in mammals?
Epidermis Dermo-epidermal junction Dermis Sub-cutis Appendages
What layer of the skin makes up the epithelium?
Epidermis
What type of epithelium is the epidermis?
Stratified squamous epithelium
Is the epidermis or dermis more cellular?
Epidermis
What of the 4 basic tissue types is the dermis?
Connective tissue
What is the sub-cutis mainly composed of?
Fat
What are the 4 skin appendages?
Nails
Hair
Glands
Mucosae
What type of epithelium lines the blood vessels?
Simple squamous epithelium
Where is glandular epithelium found in the skin?
In sweat and sebaceous glands
What is the periderm?
When does this generally disappear?
Outer layer of the bilaminar foetal epidermis
Before birth
What does the epidermis form from in the embryo?
Ectoderm cells form a single layer of periderm
There is a gradual increase in layers of cells before the periderm is cast off
What is the ectoderm?
One of 3 primary germ layers in the very early embryo
What is the embryonic origin of the dermis?
Mesoderm
What is the neural crest?
A temporary group of cells unique to vertebrates that arise from the embryonic ectoderm cell layer and in turn give rise to a diverse cell lineage
What is the embryonic origin of melanocytes?
Neural crest
At 4 weeks, what layers is the skin made up of? (3)
Periderm
Basal layer
Dermis (corium)
At 16 weeks, what layers is the skin made up of? (5)
Keratin Layer Granular layer Prickle ell Layer Basal Layer Dermis
At how many weeks is the skin fully formed with appendages?
26 weeks
What is the basal layer formed from?
Basal keratinocyte cells (“Stem cells of the skin”) and melanocytes
What “lines” show the developmental growth pattern of skin?
Blaschko’s lines - don’t follow vessels, nerves or lymphatics
What forms the basement membrane of the epithelium (epidermis)?
the demo-epidermal junction
How thick is the epidermis?
Very thin - 1.5mm thick
What cells make up 95% of the epidermis?
Keratinocytes
what structural protein does keratinocytes contain?
Keratin
Apart from keratinocytes, what other cells does the epidermis contain? (3)
Melanocytes
Langerhans cells
Merkel cells
What are melanocytes?
Melanin producing cells
What are lagerhans cells?
Dendritic cells
What are merkel cells?
Mechanoreceptors
What are the 4 layers of the epidermis with their Latin name?
Keratin layer (stratum corneum) Granular layer (stratum granulosum) Prickle cell layer (stratum spinosum) Basal layer (stratum basale/ germinativum)
How many cells thick is the basal layer generally?
1 cell thick
What is the ratio of melanocytes to basal cells in the basal layer?
1:10
what do basal cells contain lots of?
intermediate filaments - parts of the cytoskeleton
What shape are prickle cells?
Polyhedral
What does the pricked cell layer have lots of between cells?
Desmosomes (connections)
How many layers of cells does the granular layer have?
2-3 layers of flatter cells
What type of cells make up the granular layer of the skin?
Keratinocytes known as granular cells
What do granular cells contain? (2)
Large keratohyalin granules
Odland bodies
What 2 things are contained within the large keratohyalin granules of granular cells?
Filagrrin
Involucrin proteins
What are odland bodies?
Other name for these?
A type of epithelial organelle with a high lipid content
Lamellar bodies
What cells make up the keratin layer?
What are these?
Corneocytes
Type of terminally differentiated keratinocyte that is non-nucleated
What is the name for the outer part of a corneocyte that makes up the outer layer of the epidermis?
Cornified envelope - made from keratin
What creates the tight waterproof barrier of the keratin layer?
Lamellar granules release lipid
Where are keratinocytes produced?
in the basal layer
What controls the balance between cells in/ out e.g. keratinocyte production at the basal layer? (3)
What 2 conditions are caused by a loss in this control?
Growth factors Hormones Cell death Skin cancer Psoriasis
What causes white plaques in the oral mucosa?
Thickening of the oral epidermis
