The Integument Flashcards
What does the Integument provide for the body
Protection, sensation, thermoregulation, synthesis of Vit D3
What are the 4 layers of thin skin epidermis
- Stratum basale (deepest)
- Stratum spinosum
- Stratum granulosum
- Stratum coneum (most superficial)
What is the extra layer of epidermis found in thick skin
Stratum lucidum
What 4 cells comprise the epidermis?
KeMML
Keratinocytes
Melanocytes
Merkel cells
Langerhans cells
Define difference in thick vs thin skin
Thick - found in palms and soles, has 5 layers, much thicker
Thin - found throughout the body, has 4 layers, contains glands and hair follicles
Define the stratum basale
Cell composition, function, contents
Single layer of keratinocytes with stem cells
Mitotically active
Contains melanin
Define statrum spinosum
Cell composition, function
Several cell layers thick
Contains polyhedral keratinocytes with spiny processes
Produces corns and calluses
Define stratum granulosum
Cell compositor, function
Thickest layer of non-keratinized portion of the epidermis
Assembles flaggrin, which is a precursor to keratin
Define stratum corneum
A nuclear cells
Filled with mature keratin
Forms water barrier of epidermis
Continuously shed
Define stratum lucidum
A subdivision of stratum corneum, only seen in thick skin
No organelles or nuclei
What is the predominent cell within the epidermis
Keratinocytes
Define keratinocytes
Cells that produce keratin, participate in epidermal water barrier
Explain the process of keratinization
Begins with basal cell keratinocyte in the basal layer (stratum basale)
Basal cell - synthesize intermediate keratin filaments, grouped into bundles called tonofibrils
Basal cell pushed into stratum spinosum layer and becomes spinous cell
Spinous cell - begins synthesis of keratohyalin granules and glycolipid-containing lamellar bodies
Spinous cell pushed into stratum granulosum and becomes granular cell
Granular cells - discharge the laminar bodies to create a water barrier, filaggrin further promotes aggregation of keratin filaments
Now is a cornified cells which are now keratinized in the stratum corneum with no nucleus or organelles
What affects the creation of cornified cells
Ph
Define mealnocytes
Neural crest-derived cells found in stratum basale
Produced melanin and transfers it to keratinocytes
What type of tissue is the epidermis
Keratinized, stratified, squamous
Define melanin
Pigment protein that protects nuclei from UV radiation
Define the epidermal-melanin unit
One melanocyte maintains an association with a specific number of keratinocytes
How is melanin produced and excreted
4 steps
- Through the oxidation of tyrosine into DOPA by tyrosinase
- DOPA then polymerized into melanin with is UV sensitive
- Mealnosome now heads toward keratinocytes
- Transferred into keratinocytes via phagocytocis
Define langerhans cells
Antigen-presenting cells that provide defense against pathogens
Define the function of langerhans cells
Antigen is phagocytized and displayed on the cell surface
Cell then migrates to nearby lymph node to activate T-lymphocytes to destroy antigen
What are the two layers of the dermis
Papillary layer
Reticular layer
Define papillary layer
Loose CT immediately beneath epidermis
Contains thinner collagen fibers and elastic fibers
Includes vasculature and nerve endings
Define reticular layer
Deep to papillary layer
Thicker and less cellular
Contains Type I collagen and corse elastic fibers
Forms irregular lines of tension, called langer’s lines
Define meissner’s corpuscle
Touch receptors sensitive to low-frequency stimuli
Tapered cylinder oriented perpendicular to the skin surface
Present in the dermal papillae just beneath the epidermis
Define pacinian corpuscle
Large ovoid structure found in the deeper dermis and hypodermis
Detects pressure or vibration
Has myelinated nerve endings surrounded by a capsule structure
Define sebaceous glands and function
Produce a lipid mixture called sebum via holocrine secretion to lubricate and soften skin and hair
Where is sebum dischraged into
The pilosebaceous canal
What is sebum and its function
A waxy mix of triglycerides and cholesterol
Lubricates and softens skin and hair
Define eccrine sweat glands and function
Coiled glands distributed over the entire body except lips and genitalia
Uses myoepithelial cells to facilitate expulsion of secretions
Regulates temp via cooling
What do eccrine glands use to facilitate expulsion of secretions
Myoepithelial cells
Define apocrine sweat glands and fucntions
Large lumen, tubular glands
Use merocrine secretion of a ammonia rich secretion
Odorless until mixed with bacteria
Also uses myoepithelizl cells to facilitate expulsion of secretions
Draw out process of keratinization
Draw
