What constitutes malpighian layer of skin?
**Core Concept**
The malpighian layer of skin, also known as the stratum basale and stratum spinosum, is a crucial component of the epidermis. It is composed of a single layer of columnar or cuboidal cells that are responsible for the production of new skin cells through cell division.
**Why the Correct Answer is Right**
The malpighian layer is situated at the base of the epidermis and is characterized by a high rate of cell division. The cells in this layer are attached to each other by desmosomes, which provide mechanical strength to the skin. The stratum basale contains melanocytes, which produce melanin, while the stratum spinosum contains keratinocytes that produce keratin, an essential protein for skin strength. The malpighian layer is also rich in nerve endings, making it sensitive to touch and other stimuli.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the stratum lucidum is a thin, transparent layer found in the palms and soles, not the malpighian layer.
**Option B:** This option is incorrect because the stratum corneum is the outermost layer of the epidermis, composed of dead, flat cells that provide a barrier against water loss and external pathogens.
**Option C:** This option is incorrect because the dermis is the layer of skin located beneath the epidermis, composed of collagen, elastin, and other connective tissue proteins.
**Clinical Pearl / High-Yield Fact**
The malpighian layer is responsible for producing new skin cells through a process called mitosis, which is essential for skin regeneration and repair. Damage to this layer can lead to skin disorders such as psoriasis and eczema.
**Correct Answer: D. Stratum basale and stratum spinosum.**