Function of the skin Flashcards
What is one of the main functions of the skin?
Thermoregulation.
What does the skin do on a hot day?
Shunt vessels constrict to push blood to the skin surface so heat can be lost.
What does the skin do on a cold day?
Shunt vessels dilate so blood does not go to the surface of the skin and heat loss is reduced.
How is Vitamin D3 produced in the skin?
UVB photons convert 7-dehydrocholesterol to pre-vitamin D3 which is then thermally converted to Vitamin D3.
What is the role of Vitamin D3?
It regulates the levels of calcium and phosphate, reduces cell proliferation and increases cell differentiation.
What is the physical purpose of the skin?
To prevent water loss and to act as a barrier.
What does TEWL stand for?
Trans-epidermal water loss.
What is the microbiota on the skin?
The wide range of microorganisms that live on the skin.
What are some of the relationships that might exist between the skin and the microbiota?
Cmmensal - one of the partners benefits but the other suffers no harm, mutualistic - both partners benefit or pathogenic - causing or capable of causing disease.
Apart from the physical barrier the skin creates, how else does the barrier function of the skin work?
There is secretion of sebum and eccrine sweat, enzymatic breakdown of phospholipids to produce free fatty acids, extrusion of H+ in exchange for Na+ by cells in the stratum granulosum and release of acidic metabolic by-products by microorganisms.
What are AMPs and what is their function?
Antimicrobial peptides that are produced rapidly in response to invading pathogens that form a major part of the innate immune response.
What is the innate immune response?
Non-specific defense responses.
What antimicrobials do keratinocytes produce?
Beta-defensin, cathelicidin and lysozyme.
What role do keratinocytes and langerhan’s cells play in the adaptive immune system?
They cooperate in the mobilisation and targeting of cells of the adaptive immune system.
What intracellular chemical messages do keratinocytes and Langerhan’s release?
Cytokines and chemokines such as interleukins and CC/CXC-chemokine ligands.
Give examples of interleukins.
IL-1, IL-6, Tumour Necrosis Factor (TNF)-alpha.
Give examples of chemokines.
CCL20, CXCLs8.
What other role do keratinocytes and Langerhan’s cells have in the adaptive immune system?
Dynamic adjustment of tight junctions that allows Langerhan’s cells to sample antigens in the stratum corneum.
What does the rapid activation of the innate immunity lead to?
Delayed activation of adaptive immunity.
What is epidermal homeostasis?
The constant regeneration of skin cells.
Where are stem cells located in the human epidermis?
In specialised niches within the inter-follicular epidermis and bulge regions of the hair follicle.
What happens in eczema or atopic dermatitis?
The homeostasis of the skin is not maintained, the skin increases peeling (desquamation) and the barrier is weakened.
What does a weakened skin barrier allow?
More irritating chemicals can now penetrate the skin.
