The Integumentary system Flashcards
Callus versus blister
Callus: thickening of epidermis - chronic friction
Blister: separation of dermis from epidermis - acute friction
Epidermis versus dermis
Epidermis: superficial epithelial tissue
Dermis: deeper fibrous connective tissue
What type of epithelium makes up the skin?
Stratified keratinized squamous epithelium
Other names for the hypodermis
Superficial fascia
Subcutaneous layer
Made up of adipose and areolar connective tissue
5 layers of the epidermis (from deepest to surface)
Stratum basale: germinativum, dividing cells, constantly multiplying so pushes up layers
Stratum spinosum: cells look spiny (artifact) because of desmosomes, also have prekeratin (inside the cells)
Stratum granulosum: cells have granules (keratinohyalin inside), thick cell membrane, water proofing
Stratum lucidum: only in thick skin
Stratum corneum: flat sacs of thick membranes filled with keratin, no nucleus or organelles
Melanocytes
Produce melanin
Merkel’s cells
Touch receptors, connected to nerves
Dendritic cells
Immune cells in the skin
Dermal papillae
Extends into the epidermis
Function of dermal ridges
Increase friction and grip
Where do sweat pores open?
Along the crests of the ridges
What 3 pigments are found in the skin, what colour are they, and where are they found
Melanin (yellow to reddish to brown to black)
Carotene (yellow-orange)
Hemoglobin (pink hues due to the red colour)
Accumulate in the Stratum corneum and hypodermis
Function of melanin
Provides protection to cell nuclei from UV rays
Granules are found around the superficial side of the keratinocytes
UV rays can damage DNA and cause cancer
Melanin in light, dark, and darker skin
Light: melanin digested by lysosomes short distance from the basal layer
Dark: No such digestion and present in keratinocytes all over
Darker: darker melanin, more granules and more pigment in each melanocyte
Vitamin D
Sunlight stimulates deep epidermis to produce vitamin D
Helps calcium uptake from diet
Essential for healthy bones
Folic acid (vitamin B9)
Sunlight decreases folic acid
Needed for formation of new cells, anticancer
Essential during pregnancy to prevent neural tube defects
Freckles
Increased melanin in the stratum basale
Due to repeated exposure to sunlight
Moles
Clusters of melanocytes converted into melanin containing cells
Transdermal patch
Drug molecules diffuse through epidermis to the dermis
Works well for small lipid soluble molecules (estrogen, nitroglycerin, nicotine)
Nails
Modified epidermis, dead keratinized cells
Hair and nails have hard keratin unlike skin
Nail bed is the deeper layers of epidermis
Pink due to rich underlying capillaries
Lunule
White moon at base of nail
Thick bed called nail matrix
Active growing part
Damage this and the nail will not grow back
Another name for cuticle
Eponychium
What makes hair straight, wavy or kinky
Cross section the hair shaft
Round = straight
Oval = wavy
Flat = kinky
What makes hair grey
Decreased melanin and colourless air bubbles
