Integument Flashcards
What vitamin is produced by the Integument?
Vitamin D3
What is the function of the Integument?
Protection, sensation, thermoregulation, synthesis of vit D
What layers of derm make up the Integument?
Epidermis and dermis
What type of epithelium is the epidermis?
Keratinized stratified squamous epithelium
What are the 5 layers of the epidermis?
Stratum cornermen Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
What four cells make up the epidermis
Keratinocytes (most predominant) Melanocytes Markel cells (sensation) Langerhans cells (immune)
Where do we find thick skin?
Palms, soles
Fingerprints
How many layers epidermis in thick skin?
5 layers
How many layers of epidermis in thin skin?
4 layers
Where do we find thin skin?
Widespread on the body (wherever you have hair and glands)
What are some characteristics of stratum basale?
Single layer of keratinocytes with stem cells interspersed
Mitotically active
Cuboidal/low columnar
Contains melanin
Bound by desmosomes apically
Bound by hemidesmosomes basalt
What are some characteristics of the stratum spinosum?
Several cell layers thick
Contains polyhedral keratinocytes with spiny processes
Layer thickens with pressure to produce corns and calluses (high areas of use)
What are some characteristics of stratum granulosum?
Thickest layer of non-keratinized portion of epidermis
Keratinocytes contain keratohyalin granules
Irregularly shaped and variable in size
What are some characteristics of Stratum corneum?
Anucleate cells, lose nucleus and organelles
Mature keratin
Water proof - layer of lipids
Continuously shed
Thick skin: 15-40
Thin skin: 10-20
What are some characteristics of stratum lucidum?
Subdivision of stratum corneum
Only well seen in thick skin
Typically poorly stained, translucent band of cells
No organelles or nuclei
What is the predominant cell type of the epidermis?
Keratinocytes
What is epidermal water barrier?
A barrier of keratinocytes that prevents dehydration and repels water entry
What is desquamation?
Loss of squamous cells in the epidermis
What do basal cells do?
Synthesize intermediate (keratin) filaments; grouped into bundles, tonofibrils
What do spinous cells do for keratinization?
Continue keratin synthesis, begin the synthesis of keratohyalin granules and glycolipid containing lamellar bodies
What do granular cells do for keratinization?
Discharge lamellar bodies (water barrier) (lipid component)
Keratohyalin granules w filaggrin present, further promote aggregation of keratin filaments (tonofibrils)
Now a cornified cell -> keratinized
Does the pH increase or decrease as you get more superficial in the layers of epidermis?
Decreases (more acidic) because its necessary for losing cells
Describe epidermal differentiation and replacement
epidermal cell replacement is initiated by the division of stem cells in the stratum basale
New cells undergo divisions in the stratum basale and move upwards as they differentiate into keratinized cells
Where are melanocytes derived from? And where are they found?
Neural crest
Stratum basale
What do melanocytes do?
Produce melanin and transfer it to keratinocytes
What does melanin do?
Protects nuclei from UV radiation
What is an epidermal-melanin unit?
One melanocytes maintains an association with a number of keratinocytes (1:36)
How is melanin produced?
Tyrosine is oxidized into DOPA; polymerization of DOPA
Reactions occur in membrane bound organelles, premelanosomes
As more melanin is produced, premelanosomes become what?
Melanosomes
What are langerhans cells?
Antigen presenting cells that provide defense against pathogens (develop from monocytes)
Where are langerhans cells identifiable?
Stratum spinosum
What are Merkel cells?
Epidermal cells that function in cutaneous sensation (sensory perception)
Where are merkel cells found?
Stratum basale
What is merkel cell carcinoma?
A rare but highly aggressive form of skin cancer (merkel cells undergo uncontrolled proliferation)
What is the dermal epidermal junction?
Area of tissue that joins epidermal and dermal layers of skin
(Fingerprints) finger like dermal papillae project into epidermis
Complemented by epidermal protrusions (epidermal ridges)
What are the two layers of the dermis?
Papillary and reticular layer
What is the papillary layer of the dermis?
Loose CT immediately beneath epidermis
Thinnest collagen fibers, elastic fibers
Dermal papilla and ridges
Has Vasculature and nerve endings
What is the reticular layer of the dermis?
The deep layer of the dermis
Thicker and less cellular
Has langer lines (lines of tensIon)
What is the hypodermis?
Subcutaneous fascia
Adipose tissue
Energy storage site and insulation
Hair follicles
What is a Meissner’s corpuscle?
Sensory nerve endings that is sensitive to mechanical stimuli
Touch receptors responsive to low-frequency stimuli
Where do the meissner’s corpuscle present?
In the dermal papillae just beneath the epidermis
What is the pacinian corupscle?
Large, ovoid structure found in the deeper dermis and hypodermis
Fingertips, joints, peristoeum, and internal organs
Detects pressure or vibration
What are free nerve endings?
Nerve endings that terminate in the stratum granulosum
Free in that they lack connective tissue
Fine touch, heat, cold and pain
Surround hair follicles
What are sebaceous glands?
Oil glands; produce a lipid mixture of sebum via Holocene secretion
Wavy mix of triglycerides and cholesterol
What is formed when sebum is discharged into the infundibulum (Hair follicle)
A pilosebaceous canal
What are the two types of sudoriferous (sweat) glands?
Eccrine and apocrine
What are eccrine sweat glands?
Simple, coiled glands distributed over the entire body surface except lip and external genitalia
Temperature regulation via cooling (evaporation of h2o from sweat on body surface)
What are aprocine sweat glands?
Large-lumen tubular glands that use metro rinse secretion
Found int he Axilla, areola and nipple, skin around anus and external genitalia
What are the components of sweat?
Water, salt, ammonia, uric acid and mucinogen granules
Subject to cholinergic regulation
What do myoepithelial cells do?
Facilitate expulsion of secretions
What do hair matrix cells do?
Rapidly divide and account for hair growth
What are the three parts of the hair shaft?
Medulla, cortex and cuticle
What is the medulla?
Central part of the shaft (loosely connected keratinized cells)
What’s the cortex?
Largest layer, located outside the medulla (hard keratin filaments)
What is the cuticle of hair?
The outermost layer (several layers of overlapping, keratinized squamous cells)
What is the nail root?
The most proximal region, covers the nail matrix
What is the nail matrix?
It’s where stem cells divide and form keratinocytes
Nail plate remains attached to nail bed
Pushed forward by continuous growth
What is the lunula?
The crescent shaped white area near the nail matrix
What is the nail cuticle?
The extension of skin covering nail root
