Derm anatomy Flashcards
Where is thick skin found on the body?
Palms of hands, bottoms of feet, fingers, toes
Stratum corneum
Most superficial layer (20-30 cell layers thick in thick skin). All keratinocytes in this layer are dead. Layer deep to stratum is the stratum lucidum (thick skin only) or stratum granulosum
Layers of epidermis that are dead
Stratum corneum, stratum lucidum, and stratum granulosum (beginning to die)
Stratum lucidum
Thick skin only! 5-10 cell layers thick, SF: s. Corneum; D: s. Granulosum. Keratinocytes are dead in this layer
Stratum granulosum
5-10 cell layers thick. Keratinocytes are beginning to die. SF: s. Lucidum (thick skin only) or s. Corneum; D: s. Spinosum
Stratum spinosum
10-20 cell layers thick. Cells are alive but beginning to produce precursor protein for cell death in more superficial layers. SF: s. Granulosum; D: s. Basale
Stratum basale
Deepest later of the epidermis; 1-2 cell layers thick; site of cell division for SF layers of epidermis; contains melanocytes and Merkel cells. SF: s. Spinosum; D: basement membrane (separates epidermis from dermis)
Melanocyte
Present in stratum basale layer of epidermis. Produce pigment that determine skin color
Merkel Cell
Oval shaped mechanoreceptors that specialize in light/fine touch stimuli. Present in stratum basale layer of epidermis.
Layers of epidermis
(Stratum) corneum (10-20 layers thick for thick skin, less otherwise), lucidum (thick skin only, 5-10 cell layers), granulosum (5-10 layers), spinosum (10-20 cell layers), basale (1-2 cell layers). All layers are composed of stratified squamous epithelial tissue.
Papillary layer
Most superficial dermis layer. Made up of areolar connective tissue and is highly vascularized. Plays a role in temperature control with dilation/constriction of papillary loops. Papilla increase surface area with epidermis and contain meissner’s corpuscles and nociceptors. SF: basement membrane; D: d. Reticulum
Meissner’s Corpuscle
Nerve ending present in dermal papilla. Transmit sensations of fine, discriminative touch and vibration.
Dermis reticulum
Made of up dense, fibrous, irregular connective tissue; well vascularized; contains nocireceptors. SF: d. Papilla; D: adipose layer/subcutaneous layer of the hypodermis
Nociceptor
Free nerve endings that initiate sensation of pain. Present in d. Reticulum and d. Papilar (entire dermis).
Types of sweat glands
Eccrine and Merocrine
Merocrine/eccrine glands
Abundant throughout the entire body. Produces watery sweat and excretes it into tubules that connect to s. Corneum. Stimulated by sympathetic nervous system and is involved in temperature regulation (evaporative cooling).
Layers of Dermis
Papillary, reticulum.
Hypodermis
Made up of adipose/subcutaneous connective tissue. Contains pacinian corpuscles
Pacinian corpuscles
Mechanoreceptors found in hypodermis. Deep touch, pressure, vibrations.
Types of mechanoreceptors
Pacinian corpuscles, meissner’s corpuscles, Merkel’s disks, and Ruffini’s corpuscles
Apocrine gland
Produce a fluid that is secreted onto the superficial stratum lucidum. Contains proteins and lipids that are broken down by bacteria and creates body odor. Found only in axillary and anogenital region.
Hair follicle
Contains shaft, bulb, and root. Connected to arrector pili muscle (autonomic control). Next to sebaceous gland Not present in thick skin.
Sebaceous gland
Surrounds hair follicle shafts in the dermis. Produces lubricating oil (sebum) into the hair follicles to lubricate the skin and hair and kill certain types of bacteria.
Components of the integumentary system
Skin, subcutaneous tissue, appendages
What are the appendages of the integumentary system?
Sweat glands, sebaceous/oil glands, hair, hair follicles, nails
what proportion of the body’s total body mass is skin?
8%
Follow the skin regions from most deep to superficial
reticular dermis, papillary dermis, stratum basale, stratum spinosum, stratum granulosum, stratum lucidum*, stratum corneum.
The subcutaneous adipose layer is not technically part of the skin
What are the tissue types in the epithelium vs dermis
stratified sq. epithelium in the epidermis, connective tissue in dermis
cell types in the epithelium
Keratinocytes (90%), Melanocytes (10-25% of cells in basal layer), Langerhans cells, Merkel cells
What proteins are produced by cells in the epidermis
Keratin (fibrous), Filaggrin (water retention)
How many rows of cells are present in the stratum basale
1 single row of stem cells (rapid division)
Source of keratinocytes in epithelium and lifespan
Cell division in s. basale followed by migration superficially before being sloughed off at the s. corneum. The cells are largely dead upon reaching the s. granulosum. It takes 25-24 days to migrate to s. corneum
What epidermal layer are langerhans cells found in?
s. spinosum
What do the granules in the s. granulosum contain and what is this layer’s function?
- Lipid-rich secretion 2. filaggrin. These act as a water sealant (lipids) and also retain water inside the dying keratinocytes (filaggrin)
What kind of skin has a s. lucidum
thick only
Functions of the s. corneum
dead, flat, keratinized membranous sacs account for 3/4 of the epidermal thickness and continuously slough off. They provide protection from abrasion and penetration, give the skin its waterproof property, and act as a barrier against biological/chemical/physical assaults