What are the basic functions of the Integumentary system?
protection, regulation of body temperature, communication, excretion of wastes, and vitamin D production
What are the three layers of the skin?
Epidermis, Dermis, and Hypodermis/Subcutaneous
What is the structure of the epidermal layer?
thin, superficial layer of mainly stratified squamous
What is the function of the epidermal layer?
cells in deeper layers are living and dividing that push older cells to the surface where older cells die and fill with keratin to provide tough, waterproof protection
What is the structure of the dermal layer?
widely dispersed cells, highly vascular
What are the two functions of the dermal layer?
blood vessels nourish stratum basale and dermal cells, and constrict/dilate to help regulate body temperature
What is the structure of the subcutaneous layer?
connects skin to underlying structures, composed of adipose and loose connective tissue
What are the three functions of the subcutaneous layer?
insulates, cushions, energy supply
What are the layers of the epidermis?
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum
What occurs in the stratum basale?
mitosis, as cells are pushed to the surface they die due to being cut off from blood supply
What occurs in the stratum spinosum?
cells are far enough away from the dermal blood vessels that they begin to compact and die
What occurs in the stratum granulosum?
older cells develop proteins as they die, precursors to keratin
What occurs in the stratum lucidum?
thickened skin on the palms and soles due to additional wear and tear, most cells are dead and keratin precursors develop
What occurs in the stratum corneum?
dead cells are collected and filled with keratin allowing cells to be tough and offer protection and replace cells worn away by wear and tear
What happens to cells as they are pushed towards the surface?
the farther cells move, the poorer their nutrient supply becomes and they die
How does the integumentary system regulate an increase in body temperature?
as body temperature rises, nerve impulses stimulate structures in the skin and other organs to release heat, warmed blood reaches hypothalamus in brain which controls body temperature and signals muscles in walls of dermal blood vessels to dilate allowing more blood to enter them and escape to the outside, simultaneously the nervous system stimulates the eccrine glands to become active and release sweat onto the skin surface, which as evaporates carrying heat away from the surface
How is skin color determined?
how much melanin is produced from a melanocyte regulated by DNA
What is the difference between sebaceous glands and sweat glands?
sebaceous glands contain groups of specialized epithelial cells and are usually associated with hair follicles and secrete an oily mixture of fatty material and cellular debris called sebum which keeps hair and skin soft, pliable, and waterproof, while sweat glands are widespread exocrine glands in the dermis or subcutaneous line with sweat secreting epithelial cells
What are the different types of nerve receptors?
pacinian corpuscles and meissner corpuscles
What are the steps in healing an epidermal wound?
migration of epidermal cells across wound cap, cells from stratum basale migrate up edges of wound, cells from stratum basale divide until they meet in the middle (realize contact inhibition)
What are the steps in healing a dermal wound?
inflammatory phase, migratory phase, proliferate phase, and maturation phase
What are the accessory organs of the integumentary system?
hair, nails, nerve receptors
What causes variation in hair color?
melanocytes produce different pigments as detailed by the DNA
What causes hair to turn white or grey?
lack of pigment in the cortex of a hair shaft, melanin production decreases with age
What are the types of skin cancers?
squamous cell carcinoma, basal cell carcinoma, malignant melanoma
What is the stratum basale?
simple columnar cells capable of mitosis
What is stratum spinosum?
stratified cuboidal cells that are mainly dead
What is stratum granulosum
3 to 5 rows, partially flattened cells that contain proteins or granules that are precursors to keratin
What is stratum lucidum?
present only on palms and soles, it is 3 to 4 rows, flattened, dead cells containing keratin precursors
What is stratum corneum?
20 to 50 rows, flattened, dead cells, cells are filled with keratin and the ones that are lost by wear and tear are replaced by deeper cells
What occurs during the inflammatory phase of dermal wound healing?
redness (vasodilation), heat (bi-product of metabolic activity), swelling (fluids leave blood vessels into tissues, white blood cells invade), pain (neuron injury and increase in pressure due to swelling)
What occurs during the migratory phase of dermal wound healing?
epidermal cells migrate across the wound and blood clots forming scab
What occurs during the proliferate phase of dermal wound healing?
there is a reestablishment of epidermis and connective tissue below; fibroblasts migrate and form collagenous fibers, binding wound together (sutures speed up)
What occurs during the maturation phase of dermal wound healing?
phagocytes remove dead cells, cells mature to heal wound and scab falls off
What are the two regions of the dermis?
papillary region and reticular region
How is hair formed?
As epidermal cells divide and grow, older cells are pushed towards the surface. As they move upward they move further from the dermal's nutrients so they begin to keratinize and die. The remains extend away from the skin surface creating the hair shaft
How does the integumentary system regulate a decrease in body temperature?
muscles in the walls of dermal blood vessels are stimulated to contract decreasing flow of heat-carrying blood through skin reducing heat loss and sweat glands remain inactive, nervous system stimulates muscles to contract slightly increasing heat through cellular respiration and small muscles may contract rhythmically with great force causing shivering which generates more heat
What is the connection between dehydrocholesterol and vitamin D?
When dehydrocholesterol is synthesized in the digestive system it then can move to the skin and through exposure to ultraviolet light from the sun will be converted to vitamin D
What structure anchors the epidermis to the dermis?
What are the two types of intradermal injections?
subcutaneous injections go into the subcutaneous layer and intramuscular injections go into muscles
What is the difference between cutaneous carcinomas and cutaneous melanomas?
cutaneous carcinomas are caused by regular exposure to sunlight while cutaneous melanoma is cause by short, intermittent exposure to high-intensity sunlight
what are the lesion structural differences between cutaneous carcinomas and cutaneous melanomas?
carcinoma are either flat or raised, usually adhere to skin, slow growing, can be cured completely through surgery or radiation. melanoma have irregular outlines, may feel bumpy, spread horizontally through body, but may invade in the body making treatment difficult
What can the size and shape of a medulla tell us?
what species or race the hair belongs to
What information can be gained by doing a scale cast of hair?
What causes baldness (alopecia)
infection, emotional stress, drugs, radiation, male hormones
What is the structure of nerve receptors
nerve ending wrapped with connective tissue
What is the function of nerve receptors?
receive information from outside world and send to brain
What is the difference between pacinian corpuscles and meissner corpuscles?
pacinian respond to changes in deep pressure, while meissner respond to slight pressure changes and fine touch
Describe the function of protection
vs. body fluid loss, injury, UV light, microorganism
Describe the function of regulation of body temperature
insulating barrier, sweat, blood supply
Describe the function of communication
react to stimuli-cold, hot, touch, pain
Describe the function of excretion of wastes
sweat glands release waste
Describe the function of vitamin D production
UV exposure, Vitamin D helps absorb calcium through digestive tract
What can prolonged and excessive exposure to UV light cause?
prolonged exposure - increased melanin and darker skin means a tan, excessive exposure - sunburn or DNA mutations mean malignant melanoma