Skin Layers and Accessory Structures - Anatomy and Physiology
- Which epidermal layer contains the dividing stem cells that renew the epidermis?
- The stratum basale (stratum germinativum), the deepest layer, resting on the basement membrane.
- What are the two layers of the dermis and their tissue types?
- The papillary layer (areolar connective tissue) and the deeper reticular layer (dense irregular connective tissue).
- How do apocrine sweat glands differ from eccrine sweat glands?
- Apocrine glands lie in the axillary and anogenital regions, empty into hair follicles and become active at puberty; eccrine glands open directly onto the skin.
- How do living cells of the epidermis receive nutrients?
- By diffusion from blood vessels in the dermis, because the epidermis is avascular.
- Which part of the nail produces new nail cells for growth?
- The nail matrix, located at the proximal end beneath the nail fold.
- List the layers of the epidermis of thick skin from deepest to most superficial.
- Stratum basale, spinosum, granulosum, lucidum, and corneum.
- Where is the stratum lucidum found?
- Only in thick skin, such as the palms of the hands and soles of the feet.
- What does the arrector pili muscle do?
- It is smooth muscle that pulls the hair follicle upright, producing goosebumps.
- What makes up the stratum corneum?
- Many layers of dead, flattened, keratin-filled cells that protect against abrasion, water loss and microbes.
- What is the role of Langerhans (epidermal dendritic) cells?
- They are immune cells that capture antigens in the epidermis and present them to lymphocytes.
- Where do sebaceous glands usually release their secretion?
- Into hair follicles. Sebum lubricates hair and skin and slows water loss.
- Which epidermal cells produce melanin, and where do they pass it?
- Melanocytes in the stratum basale. They transfer melanin to nearby keratinocytes, where it shields the nucleus from UV light.