The Integumentary System Flashcards
Cutaneous membrane
Consists of two layers:
- Epidermis
- Dermis
Accessory structures
Hair, hair follicles, exocrine glands and nails
2 parts of integumentary system
- Cutaneous
2. Accesory
Where are the accessory structures embedded?
In the dermis
Functions of the integumentary system
- Protection of organs
- Excretion of salts
- Body temperature
- Melanin, keratin, vitamin D
- Lipid storage
- Sensory detection
- Immune response
How does the epidermis get nutrients and oxygen?
They are diffused from capillaries within the dermis
What kind of epithelial tissue is the epidermis?
Stratified squamous
Why are the cells with the highest metabolic demands closer to the basement membrane?
The diffusion distance is shorter there
Keratin
Tough, fibrous protein that makes up keratinocytes
Thin skin
- 4 layers of keratinocytes
- covers most of the body surface
Thick skin
- 5 layers of keratinocytes
- palms of hand and soles of feet
Stratum basale (epidermis)
- Attached to the basement membrane
- Epidermal ridges, dermal papillae
- Basal (stems) cells, melanocytes, tactile cells
Basal cells
Stem cells that divide to replace the more superficial keratinocytes that are shed at the epithelial surface
Where are tactile cells found?
Skin surfaces lacking hair
Tactile cells
Sensitive to touch and when compressed, release chemicals that stimulate their associated sensory nerve endings
Tactile disc
Tactile cell + sensory nerve ending
Stratum spinosum (epidermis)
Keratinocytes bound together by desmosomes
Dendritic cells
Cells in the stratum spinosum that stimulate defence against microorganisms and superficial skin cancers
Stratum granulosum (epidermis)
- Keratinocytes produce lots of keratin and cells die from keratohylin
Keratohylin
A protein made by keratinocytes which form dense cytoplasmic granules that dehydrate cells
Stratum lucidum (epidermis)
A glassy layer in thick skin only
Stratum corneum (epidermis)
- Multiple layers of flattened, dead, interlocking keratinocytes
- Water resistant but not water proof
Keratinisation
The formation of protective, superficial layers of cells filled with keratin
Insensible perspiration
Water loss from stratum corneum
Sensible perception
Water loss from active sweat glands
Where is EGF produced?
- Salivary glands
- Glands of the duodenum
Functions of EGF
Promotes:
- Division of basal cells in stratum basale and stratum spinosum
- Keratinisation
- Epidermal development and repair
- Secretions of epithelial glands
2 layers of the dermis
- Papillary: nourishes and supports epidermis
2. Reticular: detects sensory input and thermoregulates
Which layer does dermatitis primarily involve?
Papillary layer
What epithelial tissue is the papillary layer made of?
Areolar tissue
What epithelial tissue is the reticular layer made of?
Dense irregular connective tissue (collagen and elastic fibers)
Tension lines
The pattern made from fiber bundles in the skin
Why do surgeons cut parallel to tension lines?
Cuts will heal with little scarring
Cutaneous plexus
The deeper network of arteries in the subcutaneous layer
Subpapillary plexus
The layer of small arteries in the papillary layer
Contusions
(Bruises) When dermal blood vessels are ruptured, blood leaks into the dermis
2 pigments of epidermis
Melanin and carotene
Melanocytes
Produce melanin
What amino acid makes up melanin?
Tyrosine
Melanosomes
Intracellular vesicles containing melanin
How do melanocytes respond to UV exposure?
They produce more melanin
Where are melanosomes in keratinocytes?
Surrounding the nucleus, preventing damage to the DNA
Carotene
Orange yellow pigment that accumulates in epidermal cells
Which pigment can be converted to vitamin A?
Carotene
Hemoglobin
Binds and transports oxygen in the bloodstream and gives blood its red colour
Cyanosis
The bluish coloration of the skin when oxygen levels drop and hemoglobin produces lots of oxygen, turning a much darker red