B. Incorrect! Hypodermis is not part of the skin and lays under the dermis. D. Correct! The epidermis is the outermost region of the skin.

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1 Microbiology - Problem Drill 17: Microbial Infections of the Skin and Eye No. 1 of What is the name of the most external region of the skin? (A) Dermis (B) Hypodermis (C) Hyperdermis (D) Epidermis Dermis is the layer under the epidermis. Hypodermis is not part of the skin and lays under the dermis. This is not a correct term. D. Correct! The epidermis is the outermost region of the skin. The prefix epi means above, hypo means below. Therefore epidermis is above the dermis and hypodermis is below the dermis.

2 No. 2 of What tissue type does Rocky Mountain Spotty Fever infect? (A) Fibroblasts within the connective tissue (B) Glial cells surrounding the neurons (C) Endothelial cells within the blood vessels (D) Osteoblasts within the bones Although fibroblasts are associated with connective tissue, they are not the primary site of infection. Glial cells are associated with certain types of neurons, but they are not the primary site of infection. C. Correct! Endothelial cells line the capillaries and are the primary site of infection for Rock Mountain Spotted Fever. Osteoblasts are cells within bones that deposit calcium after it has been removed by osteoclasts. Removal of calcium by osteoclasts may be due to the need for calcium ions within the body or in the natural regeneration of the bones. E. Incorrect! Within the human body, multiple types of cells work together to build complex structures. Endothelial cells form the innermost lining of blood vessels. In the case of arteries, these endothelial cells are surrounded by layers of smooth muscles cells. It is rather amazing the Rocky Mountain Spotted Fever will only infect the endothelial cells and not infect the smooth muscle cells that surround the endothelial cells. Why might this be the case?

3 No. 3 of Of the organisms listed below, which are NOT bacteria? (A) Bacillus anthracis (B) Bartonella henselae (C) Simplexvirus (D) Streptococcus pyogenes Bacillus anthrais is the bacteria that causes anthrax. Bartonella henselae is the bacterial causing cat scratch fever. C. Correct! Herpes is caused by the virus Simplexvirus.. Streptococcus pyogenes causes necrotizing fasciitis and impetigo. Bacteria, virus, and fungus are very different types of organisms. They each have very unique lifecycles and growth requirements. With the exception of warts, all of the viral infections presented here are systemic infections that generate a rash on the skin, whereas all of the bacterial infections presented here are localized within the skin.

4 No. 4 of Which virus is NOT a poxvirus? (A) Cowpox (B) Pigpox (C) Chickenpox (D) Monkeypox Cowpox is a pox virus. Pigpox is an incorrect name. C. Correct! Chickenpox is the common name for Varicella-zoster virus. Although there is currently a vaccine available for VZV, the vaccine only confers immunity for about 12 years, whereas exposure to the actual pathogen will confer immunity for life. Is there an advantage to getting the vaccine rather than getting the chickenpox? Monkeypox is a poxvirus. Smallpox, cowpox, and monkeypox are all pox viruses but, chickenpox is caused by Varicella-zoster virus. Generally small children and infants are susceptible to chickenpox, but newborns are covered by the mother s immunity if she has been previously infected with chickenpox.

5 No. 5 of What is the pathogen whose infection is confined to the keratinocytes of the epidermis? (A) Rickettsia rickettsii (B) Papillomavirus (C) Staphylococcuss aureus (D) Pseudomonas aeruginosa Rickettsia rickettsii causes Rocky Mountain Spotted Fever. B. Correct! Papillomavirus causes warts and specifically infects the keratinocyte cells of the epidermis. Staphylococcuss aureus causes impetigo. Pseudomonas aeruginosa forms biofilms. In addition to keratinocytes cells, the epidermis also contain melanocyte cells that produce melanin the give the skin its color, Langerhan cells have immunological functions, and Merkle cells have sensory functions. The keratinocytes start in the stratum basale then are pushed toward the skin s surface as the existing cells within the stratum basale continue to replicate.

6 No. 6 of Why does cleansing the skin help prevent acne? (A) The hot water helps you sweat. (B) Moisturizers in the soap soften skin and thereby preventing acne. (C) Residual bacteria in the washcloth out compete Propionibacterium acnes that cause acne. (D) Washing removes dead and dying bacteria that plugs the pores of the sebaceous glands Acne occurs due to blockage of the pores of sebaceous glands not sweat glands. This is not true. Acne occurs at the sebaceous gland, and washing removes the plugs. Although washcloths often contain bacteria, they will not out compete Propionibacterium acnes. There are however, locations within the body such as the intestinal tract and the vagina where friendly bacteria prevent infection by harmful bacteria. D. Correct! Correct for two reasons. Acne occurs at the sebaceous gland, and washing removes the plugs. Being that acne is fundamentally, cosmetic, there is plenty of good information on the web regarding acne, its causes, and its prevention.

7 No. 7 of Quick and correct diagnosis is very important to proper treatment of which potentially lethal disease / infection? (A) Rocky Mountain Spotted Fever (B) Pityriasis lichenoides (C) Ringworm (D) Rubeola A. Correct! Rocky mountain spotted fever is a systemic infection that produces a rash on the surface of the skin, and is therefore much more serious than rash produced by a localized infection of the skin. Pityriasis lichenoides is a fungal infection of the keratinocytes. Ringworm is generally confined to the superficial layers of the skin. Rubeola is self-limiting There are many potential causes of a skin rash. It can either come from circumstances localized to the skin or it can be an indication of an infection that inhabits the entire body. Rocky mountain spotted fever is a systemic infection that produces a rash on the surface of the skin, and is therefore much more serious than rash produced by a localized infection of the skin.

8 No. 8 of Which layer is not part of the epidermis? (A) Stratum Corneum (B) Stratum Dermis (C) Stratum Granulosum (D) Stratum Spinosum Stratum corneum is the outermost layer that consists manly of keratin. B. Correct! Statum Dermis is not a real layer. Stratum lucidum is the second layer of the epidermis and is generally only visible in thick skin present on the palm of the hands and the soles of the feet. Stratum lucidum consist of hydrophobic molecules that form a moister barrier and prevents the diffusion of nutrients. Because the stratum lucidum stops the diffusion of nutrients, cells that are superficial to the stratum lucidum are dead, and cell stratum lucidum are living. Stratum Granulosum is the third layer from the surface of the skin. Stratum Spinosum is the fourth layer from the surface of the skin. The five layers of the epidermis, listed in order from superficial to deep, are: 1. Stratum Corneum 2. Stratum Lucidum 3. Stratum Granulosum 4. Stratum Spinosum 5. Stratum Basale

9 No. 9 of What are the two layers of the dermis? (A) Hypodermis layer and epidermis layer (B) Papillary layer and Reticular layer (C) Keratin layer and basale layer (D) Gingitive layer and Cholesterol layer The papillary layer is superficial and the reticular layer is deep. B. Correct! The papillary layer is superficial and the reticular layer is deep. The papillary layer is superficial and the reticular layer is deep. The papillary layer is superficial and the reticular layer is deep. The outer papillary layer of the dermis has ridges that are the basis of finger prints. Even though the hair follicles start in the epidermal layer and penetrate deep into the dermis they remain coated with cells from the epithelial layer. It is these epithelial cells located at that base of the hair follicles that repopulate the epithelium in the case of sever burns.

10 No. 10 of The bite of which animal can transfer Leishmania? (A) Mosquitoes (B) Cats (C) Rats (D) Sand Flies Mosquitoes transfer West Nile virus as well as Malaria Cat bites are involved in cat scratch fever. Rodents are the natural reservoir and it is the bite of the sand flies that transfers Leishmania to humans. D. Correct! Rodents are the natural reservoir and it is the bite of the sand flies that transfers Leishmania to humans. Leishmaniasis is a disease that is caused by parasites that belong to the family Leishmania. The disease is typically transmitted by the bite of certain species of sanfly.