Skin Histology Overview Flashcards
What are the epidermal layers of the skin from superficial to deep?
Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale
What is the highest epidermal layer in which living cells are found?
Stratum granulosum
What are the characteristics of the granules produced by the stratum granulosum?
Lipid-containing, membrane coated lamellar granules; exocytosed to produce a waterproof barrier
What are the characteristics of the stratum corneum?
Composed of non-nucleated keratinocytes, important to barrier function
What is orthokeratosis?
Normal “basket-weave” stratum corneum
Epidermal cells in the stratum spinosum are joined together by what type of cell junction?
Desmosomes
Stratum lucidum is only found in what type of skin?
Acral skin
What type of keratosis is seen in acral skin?
Compact orthokerarosis
What are the four types of cell found in the epidermis?
Keratinocytes, melanocytes, Langerhans cells, and Merkel cells
Melanocytes are found in which layer of the skin?
Stratum spinosum
What type of embryological cells are keratinocytes derived from?
Neural crest cells
What is the function of Langerhans cells?
Antigen presenting cells that reside in the epidermis
What are Birbeck bodies?
Tennis racket shaped cytoplasmic organelles found only in Langerhans cells
Langerhans cells are found in which layer of the skin?
Stratum spinosum
Where are Merkel cells found?
Dermis and epidermis
What is the function of Merkel cell aggregates?
Act as tactile corpuscles
What are the six primary components of the dermis?
Collagen, elastic tissue, fibroblasts, epidermal appendages, blood vessels, and nerves
What are the histological features of solar elastosis seen with an H&E stain?
Blue-grey discoloration of elastic fibers
How do merocrine glands secrete their contents?
Vesicles containing secretory products release their contents into the duct
How do apocrine glands secrete their products?
Secretory products stored in the cell are released into by pinching off of part of the cell membrane.
How do holocrine glands secrete their products?
The entire cell containing secretory products is shed into the duct; the cell then dies and releases its secretory products
What are the components of the pilosebaceous unit?
Hair follicle, sebaceous gland, and arrector pili muscle
Sebaceous glands are found everywhere EXCEPT in what type of skin?
Acral skin on the palms and soles
What is the function of sebum?
Provides emollients to the skin and hair
When do sebaceous glands become functionally active?
At puberty
Sebaceous glands undergo what type of secretion?
Holocrine secretion
Where are apocrine glands typically found?
Axillae and groin
When do apocrine glands become functionally active?
At puberty
What stimulates the secretion of apocrine glands?
Excitement or fear
Why is the secretion of apocrine glands odorous?
Action of cutaneous microorganisms
Where are eccrine sweat glands typically found?
Everywhere except mucous membranes
What is the hypodermis (subcutis)?
The fat layer that separates the dermis from deeper underlying structures
What is the purpose of the hypodermis?
Insulates the body, serves as an energy supply, cushions and protects the skin, and allows for mobility over underlying structures
What is hyperkeratosis?
Thickened stratum corneum
What is acanthosis?
Thickened spinous layer
What is acantholysis?
Loss of attachment between keratinocytes
What is parakeratosis?
Presence of keratinocytic nuclei in the stratum corneum
What is spongiosis?
Intraepidermal accumulation of edematous fluid in intracellular spaces
What is hypergranulosis?
Increased thickness of the stratum granulosum
