Integumentary System Flashcards
Cutaneous
Related to skin
What are the functions of integumentary system
Protection, sensation, thermal regulation, production of Vit D and excretion
Protection
Skin acts as a physical barrier and protects inner body structures from external chemicals and pathogens and prevents dehydration
Sensation
Skin is innervated- nerve fibers in skin transmit information about temperature, touch, pressure, pain
Thermal regulation
Blood vessels in skin and sweat glands regulated heat loss from the body
Production of vitamin D
UV light activates a precursor compound in skin to make vitamin D
Excretion
Sweat glands secrete water, electrolytes, and small amounts of Urea
Can also help with thermoregulation
What are the three main layers of the skin
Epidermis, dermis, hypodermis
Epidermis sublayers
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosun
Stratum basale
Epidermis features
Stratifed squamous epithelium
Varies in thickness
Avascular
Innervated for tactile sensation
Constantly renewing itself
What cells in sub layer are constantly regenerating and being pushed towards apical layer
Basale
Stratum corneum
Most superficial layer of epidermis that continuously get shed
Desquamation
Constant shedding of flaking apical layers as deeper basale cells regenerate
Made up of dehydrated dead keratinocytes
Keratinocytes
Main skin cells in epidermis
Keratin
Protein produced by keratinocytes
Provide strength and prevent dehydration
Found in human hair and nails
Stratum lucidum
Made up of dead keratinocytes and keratin
Optional layer: found only in thick skin on palms and soles
Stratum granulosum
Made up of dying keratinocytes, keratin and keratohyalin
As keratinocytes migrate away from blood capillaries cells begin to die in this layer
Keratohyalin
Intracellular protein that promotes dehydration of the dying keratinocytes
Gives the cells in stratum granulosum a grainy appearance
Stratum spinosum
Made up of living keratinocytes actively making keratin
Appearance is due to spikey bundle of prekeratin protein
Stratum basale
Made up of single row of mitoticly active stem cells, tactile epithelial cells and melanocytes
Stem cells
Specialize precursor cells that can divide continuously into new cells
Can differentiate into keratinocytes, tactile epithelial cells and melanocytes
Tactile epithelial cells
Merkel cells
Acts as touch receptors
Melanocytes
Produce pigment
Melanin
Black or brown skin pigment
Protect skin against UV radiation which damages DNA
How is skin tone determined
By the amount of melanin produced not the number of melanocytes
Dermis
Layer of skin between epidermis and hypodermis
Connective tissue proper
Contains blood vessels, nerves, hair follicles and glands
Vasoconstriction
When dermis is exposed to cold, blood vessels in skin constrict to conserve blood
Vasodilation
When dermis is exposed to hear, blood vessels dilate to help release heat