Skin structure and Function Flashcards
What is the epidermis?
- Outer layer of skin
- Stratified cellular epithelium
What is dermis?
- Beneath epidermis
- Connective tissue
Where does epidermis come from?
- Ectoderm cells which form single layer of periderm
- Gradual increase in layers of cells
- Periderm cells cast off
How is dermis formed?
From mesoderm below ectoderm
Where do melanocytes come from and what are they?
From neural crest
-Pigment producing cells
When is gastrulation?
Days 7-10 of foetal development
What is gastrulation?
Cellular organisation into germ layers
The layers of skin 4 weeks into foetal skin development from top to bottom?
Periderm
Basal layer
Dermis (corium)
The layers of skin 16 weeks into foetal development from top to bottom?
Keratin layer Granular layer Prickle cell layer Basal layer Dermis
Foetal skin development 26 weeks?
Epidermis Melanocyte Sebaceous gland Arector pilli muscle Hair follicle
What is the developmental growth pattern of skin called?
Blaschako’s lines
What does the skin consist of?
- Epidermis
- Appendages: nails, hair, glands, mucosae
- Dermo-epidermal junction
- Dermis:connective tissue
- Sub-cutis: predominantly fat
Type of cell that makes up epidermis?
Stratified squamous epithelium
Which layer is made up of 95% keratinocytes?
Epidermis
Other cells in the epidermis?
Melanocytes
Langerhan cells
Merkel cells
4 layers of the epidermis?
- Keratin layer
- Granular layer
- Prickle cell layer
- Basal layer
How regulation of epidermal turnover is controlled?
Growth factors
Cell death
Hormones
Loss of control in regulation of epidermal turnover?
Skin cancer
Psoriasis
Describe the basal layer?
- 1 cell thick
- Small cuboidal
- Loss of intermediate filaments (keratin)
- V metabolically active
Describe the prickle cell layer?
-Large polyhedral cells
-lots of desmosomes
0Intermdeiate filaments (keratin) connect to desmosomes
Describe the granular layer?
2-3 layers of flatter cells
- Large keratohyalin granules
- Cell nuclei lost
What retains water in the skin?
Broken down filagrin
-Granules are full of proteins like filagrin and it is prtealysed by proteases into short filagrin
The granular layer is above the granular layer. True or false?
FALSE
keratin is above granular layer
Type of cells in keratin layer?
Corneocytes
