Environmental Flashcards
What is often referred to as the sunburn or erythema spectrum and s about 1000 times more erythemogenic that UVA?
UVB (290-320)
What penetrates deeper into the skin that UVB and is the spectrum associated with photosensitivity reactions?
UVA (320-400)
What is the wavelength range most damaging to skin?
320-340
What light is partially reflected, absorbed, and transmitted inward?
UVL
Absorbed light raised the energy level of light-absorbing molecules called what? This results in various biochemical processes that can damage visually any component of a cell. This damage can result in cellular hyperporliferation, mutagenesis, alteration of cell surface markers and toxicity.
Chromophores
Chromophores in the skin include keratin proteins, blood, hemoglobin, porphyrin, carton, nuncelric acids,melanin, lipoproteins, peptide bonds and aromatic amino acids such as tyrosine, tryptophan and histidine.
List the aromatic amino acids
tyrosine, tryptophan and histidine.
What are natural barriers of UVL damage?
SC, melanin, blood and carotenes
_________ is the classic sunburn reaction and is dose-related response to light exposure. ________ occurs when the skin has increased susceptibility to the damage effect of UVL because of the production, infection, injection, or contact with a photodynamic agent.
Phototoxicity
Photosensitivity (UVL light)
What type a dermatitis occurs from actinic reaction on white or light skin? The condition develops when skin is exposed to direct or reflected sunshine
Solar dermatitis
For every 300m increased in elevation, the suns intensity increased by __%.
4%
What may be particularly important in the pathogenesis of solar damage. These substances deplete antioxidants, recruit neutrophils and destroy and degrade all components of connective tissue?
Oxygen intermediates - superoxide radial and hydrogen peroxide
Describe the biphasic apoptosis that occurs in solar damage?
Some apoptotic keratinocytes are seen within 4 hours of exposure due to OVAs direct damaging effect on the cell membrane. Other apoptotic cells appear about 24 hours after exposure. This delayed damage is a result of DNA alteration.
What is an actinic reaction in poorly pigmented nasal skin of dogs. The affect dogs may be born without pigment, or the nose may have undergone spontaneous noninflammatory depigmentation.
Canine Solar Dermatitis
What breed is predisposed to developing solar dermatitis?
The Australian shepherds appear to be an increased risk.
Found principally at the junction between the haired and non haired skin of nose.
What is the histologic description of solar dermatitis?
The early depigmentareas of the nose show fewer melanocytes and less melanin pigment than are seen in normal skin. After exposure to solar radiation, epidermal hyperplasia with intraepidermal edema is observed. Vacuolated (sun burn cells) and apoptotic keratinocytes are seen.
Solar elastosis is usually NOT seen and requires special stains (PAS)
What is a chronic actinic dermatitis of white ears and occasionally the eyelids, nose and lips of cats?
Feline Solar Dermatitis