Term
| What are the 3 layers of the skin? |
|
Definition
| epidermis, dermis, hypodermis |
|
|
Term
|
Definition
| made of 4 or 5 layers and there are germ cells in the stratum basale - these take 2 weeks to reach the stratum corneum and then 2 more weeks to shed |
|
|
Term
| What % of the skin is dermis? |
|
Definition
|
|
Term
| What does the dermis consist of? |
|
Definition
| sweat glands, sebaceous glands, connective tissue, blood vessels, and hair follicles |
|
|
Term
| What is the hypodermis made of? |
|
Definition
|
|
Term
| What are the functions of the skin? |
|
Definition
| protection, thermoregulation, immune, sensation, excretion |
|
|
Term
| How does the skin protect us? |
|
Definition
| UV radiation - melanocytes * abrasion - stratum corneum * dehydration - keratinocytes |
|
|
Term
| What structures in the skin help with thermoregulation? |
|
Definition
| capillaries, adipose tissue, and sweat glands |
|
|
Term
| What are the immune cells in the skin? |
|
Definition
|
|
Term
| What are the sensory receptors in the skin? |
|
Definition
| meisner's corpuscles, pacinian corpuscles, merkel cells |
|
|
Term
|
Definition
| sweat and sebaceous glands |
|
|
Term
| What is the storage mechanism in skin? |
|
Definition
|
|
Term
| What does the skin manufacture? |
|
Definition
|
|
Term
| What is the main barrier in the skin? |
|
Definition
| the stratum corneum - it's thick and only very small agents can penetrate - pesticide exposure is a concern, like organophosphorus pesticides are neurotoxic with skin exposure |
|
|
Term
| What happens if you have psoriasis or burns? |
|
Definition
| things can get in a lot more easily - the underlayers are not much protection b/c hydrophilic things get into intercellular water easily and hydrophobic things can get into the cells |
|
|
Term
| What 2 things contribute to the absorption rate in the skin? |
|
Definition
| hydrophobicity - low MW and hydrophobic penetrate better than high MW and hydrophilic * rate of diffusion - thin skin absorbs faster |
|
|
Term
| What are the advantages of transdermal drug delivery over oral dosing (3)? |
|
Definition
| steady infusion for extended periods * prevents exposure to acidic pH of the stomach * you avoid 1st pass removal by the GI tract or liver |
|
|
Term
| Where are the major sites of biotransformation in the skin and what enzymes are there? |
|
Definition
| the epidermis and the pilosebaceous units - p450, epoxides, reductases, glutathione, esterases, hydrolases |
|
|
Term
| What kind of biotransformation can be done in the skin? |
|
Definition
| chemicals can be degraded or activated |
|
|
Term
| What are the 2 types of contact dermatitis? |
|
Definition
| irritant and allergic dermatitis |
|
|
Term
| Is irritant dermatitis an immune reaction? What is it caused by? |
|
Definition
| no - caused by strong chemicals and noxious substances |
|
|
Term
| What type of reaction is allergic dermatitis? What do you have to have for this to occur? |
|
Definition
| a delayed type hypersensitivity * must be sensitized, have sufficient contact with sensitizing material, and have repeated contact |
|
|
Term
| What are the benefits of UV exposure? |
|
Definition
| makes vitamin D, photosynthesis, photoisomerizes bilirubin in newborns, can be used to treat psoriasis |
|
|
Term
| What are some adverse responses to UV radiation? |
|
Definition
| sunburn, skin darkening,pigment changes like freckling, wrinkling, hypomelanotic areas, cancer, reduced number of langerhans cells |
|
|
Term
|
Definition
| minimum erythema dose - the amount of UV needed to cause sunburn |
|
|
Term
| What makes you have chills and fever when you have a bad sunburn? |
|
Definition
| IL-1, which is released from keratinocytes |
|
|
Term
| What does UV absorption by the skin depend on? |
|
Definition
| the chromophore (mainly DNA and melanin), epidermal thickness, water content of the skin |
|
|
Term
| What are some environmental conditions that affect UV exposure? |
|
Definition
| altitiude, season, duration of exposure, body site, skin pigmentation, and previous exposures |
|
|
Term
| What can happen to the stratum corneum upon exposure to UV? |
|
Definition
|
|
Term
|
Definition
| a very disfiguring form of acne |
|
|
Term
| What is chloracne caused by? What are the symptoms? |
|
Definition
| caused by halogenated aromatic hydrocarbons like agent orange - straw colored cysts on the genitals, shoulders, back, and behind the ears, discoloration of nails, increase in atypical hair, acne |
|
|
Term
| What is photosensitivity? |
|
Definition
| an abnormal sensitivity to UV and visible light - genetic and autoimmune diseases impair the cell's ability to repair UV induced damage |
|
|
Term
|
Definition
| reaction as a result of chemicals + UV exposure - skin reddens and burns within minutes or hours of UV exposure |
|
|
Term
| What causes phototoxicity? |
|
Definition
| the chemical absorbs UV light, goes to a higher state, transfers energy to O2 which then forms free radicals that damage cells |
|
|
Term
| What is phytophotodermatitis? |
|
Definition
| a condition in limes and celery where psoralens intercalate with DNA and when when they get excited by UV-A it causes a reaction that inhibits DNA synthesis and repair |
|
|
Term
| What is a granulomatous disease? |
|
Definition
| granulomas form in response to the body trying to wall off something like foreign bodies or leprosy or TB |
|
|
Term
|
Definition
| type IV DTH, UV light converts a chemical to a hapten that causes an allergic reaction - requires prior sensitization |
|
|
Term
| What is urticaria? What causes it? What are common causes? |
|
Definition
| hives - type I hypersensitivity * release of histamine and vasoactive chemicals from mast cells * aspirin, dyes and toxins can cause mast cell degranulaion, but most common is systemically ingested things (something you ate) - latex, shellfish, etc |
|
|
Term
| What is toxic epidermal necrolysis? What causes is? What are the characteristics? |
|
Definition
| condition that is life-threatening * often caused by drugs and chemicals like carbamazepin - there is a reduced l'cyte capacity to metabolize toxic intermediates of the drug *results in full thickness epidermal necrosis and sloughing |
|
|
Term
| What specifically causes skin cancer? What is the target gene? |
|
Definition
| UVB induces pyrimidine dimers and damages epidermal cell DNA- UV light is immunosuppressive, so it helps skin tumors survive * p53 is the target - this normally arrests cell cycling so DNA can be repaired |
|
|
Term
| What are some PAHs that cause cancer? How do they cause cancer? |
|
Definition
| soot, tar, pitch, creosote * oxidative biotransformation makes electrophilic epoxides that form DNA adducts |
|
|
Term
| How does arsenic affect the skin? |
|
Definition
| alters methylation, suppresses keratinocyte differentiation, and enhances epidermal growth factor secretions |
|
|
Term
| What diseases can arsenic cause? |
|
Definition
| arsenical keratosis, blackfoot, and squamous cell carcinoma |
|
|
