Derm summary 1

Question 1

What are the five primary functions of the skin?

Answer 1

1. Acts as a physical, chemical, and immunological barrier
2. Regulates temperature
3. Provides sensory input
4. Synthesizes vitamin D
5. Largest organ of the body

Question 2

What is the structure and function of the epidermis?

Answer 2

Outermost skin layer
Made of keratinized stratified squamous epithelium
Acts as a waterproof barrier

Question 3

Describe the dermis and its components.

Answer 3

Lies beneath the epidermis
Composed of connective tissue
Contains collagen, immune cells, blood vessels, and appendages

Question 4

What are basal cells and where are they found?

Answer 4

Located at the base of the epidermis
Anchored to the dermis via collagen attachments

Question 5

What are skin appendages and what is their clinical significance?

Answer 5

Include sweat glands, sebaceous glands, and hair follicles
Breach the epidermal barrier, allowing microbial invasion

Question 6

What is the difference between resident and transient flora on the skin?

Answer 6

Resident flora: Stable, quickly repopulate, protective role
Transient flora: Acquired, easily removed, less stable

Question 7

Name four major genera of resident skin flora.

Answer 7

1. Cutibacterium spp.
2. Corynebacterium spp.
3. Staphylococcus spp. (esp. S. epidermidis)
4. Micrococcus spp.

Question 8

Which fungal species is common in sebaceous areas of the skin?

Answer 8

Malassezia spp. (lipophilic yeast)

Question 9

Which two mites are part of normal skin flora and are linked to rosacea?

Answer 9

1. Demodex folliculorum
2. Demodex brevis

Question 10

What types of microbes typically predominate above the waist?

Answer 10

Gram-positive organisms: Cutibacterium, Staphylococcus, Streptococcus

Question 11

What types of microbes are commonly found below the waist?

Answer 11

Mixed flora:
Gram-positive: e.g., Enterococcus spp.
Gram-negative: e.g., Enterobacteriaceae

Question 12

Where do skin microbes primarily reside?

Answer 12

Superficial layers, crevices, and pilosebaceous units

Question 13

What percentage of skin bacteria are found in follicles?

Answer 13

Up to 20%

Question 14

How are microbes shed from the skin?

Answer 14

Through desquamation (skin turnover)

Question 15

What effect does skin occlusion (e.g., from diapers) have on skin flora?

Answer 15

Increases skin hydration above 100%, disrupting normal flora

Question 16

Explain the microbial changes leading to nappy rash.

Answer 16

1. Occlusion → moist environment
2. Overgrowth of Proteus spp. → urea breakdown → increased pH
3. Secondary overgrowth of Candida spp.
4. Results in bright red lesions & irritation

Question 17

List five natural defenses of the skin against microbes.

Answer 17

1. Dryness: inhibits Gram-negative bacteria
2. Acid mantle (pH 4–6): favors resident flora
3. Salt in sweat: inhibits pathogens
4. Desquamation: removes microbes
5. Keratin barrier: physical defense against entry