Lecture 8- Skin Flashcards
What are the functions of skin?
1) Protect against injury
2) Protect against pathogens
3) Waterproofing and fluid conservation
4) Thermoregulation
5) Absorption of ultra violet radiation
and vitamin D production
6) Sensory organ
7) Cosmetic
What are the three layers of skin?
1) Epidermis
2) Dermis
3) Subcutis
Which apendigial structures are found in skin?
1) Pilo-subcutaneous unit
- Follicle
- Hair shaft
- Sebaceous gland
- Pilo erecti muscle
2) Sweat glands
- Apocrine
- Eccrine
What is found in the epidermis?
Keratinocytes
Melanocytes- produce melanin
Langerhans- APCs
Merkel Cells- sensation
What do defects in the stratum corneum layer of the epidermis lead to?
Eczema
What is found in the dermis?
- Connective tissue- collagen, elastin, GAGs
- Fibroblasts synthesise these molecules
- Dermal dendritic cells
- Immunocompetent cells
How is the integrity of the demo-epidermal junction maintained?
- the two layers are attached by hemi-desmosomes, anchoring plaques and proteins
which disorder could be caused by abnormalities in these proteins?
Epidermolysis Bullosa
What is found in the subcutis?
- connective tissue
- fat
What is the difference between the two types of sweat glands?
Eccrine- sweat secreted directly onto skin
Apocrine- sweat secreted into hair follicle
What part of the melanocyte produces melanin?
Melanosomes
What happens to the melanin after they’ve been produced by the melanocyte?
- The melanin is packaged into granules
- The granules move down the dendritic process
- transferred by phagocytosis to adjacent keratinocytes
What is the function of melanin in keratinocytes?
- The melanin forms a protective cap around the keratinocyte nucleus
- Protects the DNA from UV damage
- causes skin pigmentation
What stimulates melanin production?
UV
What causes the differences in pigmentation between ethnic groups?
- NOT difference in melanocytes
- CHANGE in number and size of melanosomes produced
