Which of the following types of wounds match the criteria: plantar aspect of foot, met heads, heel?

Correct Answer: D

Rationale: Diabetic wounds, particularly diabetic foot ulcers, are commonly located on the plantar aspect of the foot, including the metatarsal heads (met heads) and heel, due to neuropathy, poor circulation, and repetitive pressure in diabetic patients. Arterial wounds are typically found on the toes or shins due to poor arterial blood supply, not specifically the plantar surface. Plantar is a location (bottom of the foot), not a wound type, so it doesn't fit as a category. Venous wounds are usually around the ankles or lower legs due to venous insufficiency. Diabetic wounds align perfectly with the described locations because of the predisposition to pressure points and poor healing, making it the correct choice.

Correct Answer: D

Rationale: Urticaria, commonly known as hives, is a skin condition characterized by raised, itchy welts due to allergic or other triggers. Keloids are overgrown scars, not hives. Seborrhea involves oily, scaly skin, unrelated to hives. Eczema causes itchy, inflamed skin but typically as patches, not distinct welts like hives. Urticaria specifically matches the definition of hives, with its hallmark transient, raised lesions, making it the correct disease.

Correct Answer: D

Rationale: The epidermis consists of multiple layers, but not all are present in every region of the body. The stratum lucidum, a thin, translucent layer of dead cells, is found only in thick skin, such as the palms and soles, where it lies between the stratum granulosum and stratum corneum. It is absent in thin skin, which covers the head, torso, and most of the body, where the epidermis transitions directly from the stratum granulosum to the stratum corneum. The stratum spinosum provides strength, the stratum corneum serves as the protective outer barrier, and the stratum granulosum aids in keratinization all present in both thick and thin skin. The stratum germinativum, though not an option here, is universal as the basal layer. The absence of the stratum lucidum in thin skin reflects its adaptation to less mechanical stress, unlike the thickened, friction-resistant skin of the hands and feet. Thus, the layer missing from the head and torso is the stratum lucidum.

Correct Answer: A

Rationale: The epidermis is a dynamic tissue where cells are continuously renewed. The stratum germinativum, the deepest layer, generates new cells via mitosis. These cells migrate upward, differentiating through the spinosum, granulosum, and, in thick skin, lucidum layers, before reaching the stratum corneum as dead, keratinized cells. This process, known as epidermal turnover, takes approximately 15-20 days in healthy adults, though it can vary slightly (e.g., 10-30 days) depending on age, health, and location. A 6-8 week or 12-15 week timeline is far too long for this cellular journey, as it would imply a sluggish renewal rate inconsistent with the skin's protective role. An 8-10 day estimate is too short for full differentiation and migration. The 15-20 day range reflects the balance between cell production and shedding, supported by dermatological studies, ensuring the skin maintains its barrier function efficiently.

Correct Answer: A

Rationale: Langerhans cells are immune cells (dendritic cells) primarily located in the stratum spinosum of the epidermis, where they play a key role in detecting pathogens and initiating immune responses. The stratum spinosum, with its multiple layers of spiky keratinocytes, provides an ideal environment for these cells to patrol for invaders. The stratum corneum, being composed of dead, keratinized cells, lacks living cells like Langerhans. The stratum granulosum is a thin layer focused on keratin production, not immune function, and the stratum basale, while active in cell division, hosts fewer Langerhans cells compared to the spinosum. Research on skin histology confirms that Langerhans cells are most abundant in the stratum spinosum, aligning with their role in immune surveillance.