Changes: Epidermis (skin)

Revision as of 23:54, 19 January 2016

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)

File:HautFingerspitzeOCT.gif

Optical coherence tomography tomogram of fingertip, depicting stratum corneum (~500µm thick) with stratum disjunctum on top and stratum lucidum (connection to stratum spinosum) in the middle. At the bottom superficial parts of the dermis. Sweatducts are clearly visible.

Epidermis is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface and is made up of stratified squamous epithelium with an underlying basal lamina.

Components

The epidermis is avascular (contains no blood vessels) and is nourished by diffusion from the dermis. The main type or the four principal types of cells which make up the epidermis are keratinocytes, melanocytes, Langerhans cells and Merkels cells. It is a keratinized stratified squamous epithelium.

Layers

The epidermis is divided into many layers where cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate and become filled with keratin. They eventually reach the top layer called stratum corneum and become sloughed off, or desquamated. This process is called keratinization and takes place within weeks. The outermost layer of epidermis consists of 25 to 30 layers of dead cells.

Sublayers

Epidermis is divided into the following 5 sublayers or strata, listed from the superficial to deep:

Stratum corneum
Stratum lucidum (not present in thin skin, only thick, hairless skin of palms & soles)
Stratum granulosum
Stratum spinosum
Stratum germinativum (also called "stratum basale")

It is the deepest layer of the skin specifically the epidermis. the anatomical structure of it is composed of a single row of cuboidal of columnar keratinocytes.

Mnemonics used for remembering the layers of the skin (using "stratum basale" instead of "stratum germinativum"):

"Corn Lovers Grow Several Bales" (from superficial to deep).
"Come Lets Get Some Beers" (from superficial to deep).
"Before Signing, Get Legal Counsel" (from deep to superficial).
"Californians Love Girls in String Bikinis" C-L-G-S-B(from superficial to deep) .
"Come Lets Get Sun Burnt" (from superficial to deep).

Additional images

External links

Histology at Boston University 08422loa - "Integument: thick skin"

This page uses Creative Commons Licensed content from Wikipedia (view authors).

@@ Line 22: / Line 22: @@
 [[Mnemonic]]s used for remembering the layers of the skin (using "stratum basale" instead of "stratum germinativum"):
-* "'''C'''orn '''L'''overs '''G'''row '''S'''everal '''B'''ales" (from superficial to deep)
+* "'''C'''orn '''L'''overs '''G'''row '''S'''everal '''B'''ales" (from superficial to deep).
-* "'''C'''ome '''L'''ets '''G'''et '''S'''ome '''B'''eers" (from superficial to deep)
+* "'''C'''ome '''L'''ets '''G'''et '''S'''ome '''B'''eers" (from superficial to deep).
-* "'''B'''efore '''S'''igning, '''G'''et '''L'''egal '''C'''ounsel" (from deep to superficial)
+* "'''B'''efore '''S'''igning, '''G'''et '''L'''egal '''C'''ounsel" (from deep to superficial).
-* Californians Love Girls in String Bikinis C-L-G-S-B(from superficial to deep)
+* "'''C'''alifornians '''L'''ove '''G'''irls in '''S'''tring '''B'''ikinis" C-L-G-S-B(from superficial to deep) .
+* "'''C'''ome '''L'''ets '''G'''et '''S'''un '''B'''urnt" (from superficial to deep).
 ==Additional images==

v·d·e Integumentary system
Structures	Skin • Sweat glands • Sebaceous glands • Hair (Hair follicle) • Nails • Scale
Layers	Cutis: Epidermis (Stratum corneum, Stratum lucidum, Stratum granulosum, Stratum spinosum, Stratum germinativum/basale) • Dermis Subcutaneous tissue