more on integumentary system Flashcards
important functions of the skin
covering, waterproof, barrier from foreign invasions, protection from UV, heat control, sensory receptors, vitamin D production and excretion
how does the skin protect from UV rays
melanocytes produce melanin that also absorbs UV light
-UV damage is a cause of cancer
skin is the ______ organ
largest
what are the layers of the skin (superficial to deep)
epidermis, dermis, and hypodermis
epidermis
consists of squamous epithelial cells and dead cells
-thickest where there is abrasion
squamous epithelial cells
stratified into 5 layers and keratinized (no nucleus)
dead cells
filled with keratin (protein), constantly shed (desquamation) and replaced
what is the deepest layer of the epidermis called
stratum germinativum
importance of the stratum germinativum
cells divide here
-contains melanocytes
dermis
dense connective tissue
-contains blood vessels, nerves, lymph, smooth muscle, sweat glands, hair follicles, and sebaceous glands
dense connective tissue
collagenous and elastin fibers
hypodermis
subcutaneous, fatty tissue adipose
-attaches dermis to muscle or bone
what are the two main accessory structures of the skin
hair and nails
hair
the shaft is visible and the root is within the epidermis in a hair follicle
-follicle is within epidermis and dermis
-contains arrector pilli muscle, follucle, papilla, sebaceous glands, and adipose
nails
modification of leathery epidermal cells with hard keratin
-air mixed with keratin makes lunula (crescent point at proximal end)
-nail root within nail bed is where growth occurs
sebaceous glands
along wall of hair follicles
-produces sebum
-controlled by the endocrine system
sweat glands
to cool and secrete minimal waste
-tubular (twisted) glands in most parts of skin
-sweat contains sodium chloride, urea, uric acid, and ammonia
apocrine sweat glands
within armpits and around genitalia
where are sweat glands most abundant
palms of hands and soles of feet
ceremonious glands
modified apocrine sweat glands with contributions from sebaceous glands
-lubrication and protection within ear canal
-only within dermis of the external auditory canal
melanoma
a type of skin cancer
-most dangerous
-least common
-ABC’s
what are the ABC’s for melanoma
A : asymmetry
B : border that are uneven vs smooth (melanoma vs. benign)
C : color variety or change
D : diameter that is relatively large
E : evolving, changing in size, shape, elevation, color, etc.
waardenburg syndrome
genetic and congenital condition
-mutation that changes melanocytes
-changes of pigmentation os skin, hair and eyes
-can have moderate to profound HL
dermatomes
an area of skin supplied by a single afferent spinal nerve (from a single dorsal root)
-carries certain information to a particular point
myotomes
segmental muscular nerve supplies overlap
-within most large muscles
-similar to dermatomes but with muscles
sclerotomes
one of the bony, cartilaginous, or membranous portions which separates the myotomes
-connective tissue that separates muscles
cutaneous receptor distribution
not uniform
-areas may be densely innervated than other areas (such as lips and fingertips)
-can test by two point discrimination
excretion
electrolytes excreted when levels are high in blood
-composed of lactic acid, urea, uric acid and ammonia (metabolic waste)
vitamin D
UV promotes skin production of a precursor to vitamin D
-needed for absorption of calcium and phosphorus within GI tract
-calcium for muscle contraction and bone growth
dermatitis
skin inflammation or infection
psoriasis
red patches, thick, scaly, may bleed, hyperactive stratum germinativum
-occurs due to pushing up too many new cells
warts
uncontrolled growth in epidermal layer
-human papillomavirus
cold sores
fluid filled blister
-herpes simplex virus
impetigo
small blisters
-staphylococcus aureus bacteria
-highly contagious (face and can spread)
furuncle or boil
staph infection of hair follicle or gland with pus
urticaria or hives
localized edema in epidermis
-elevated, red or pale and itchy
external otitis
infection in ear canal
-bacterial or fungus
swimmer’s ear
type of external ear canal infection
-typically bacterial
otomycosis
fungal infection
necrotizing external otitis
the eating away of the skin or even bone within the ear canal
thermoregulation
sweating occurs to reduce hyperthermia
-a vascular change (autonomic)
-vasodilation and vasoconstriction
vasodilation
smooth muscle in blood vessels of the skin relax/open to allow more blood to enter the skin
-blood transports heat which this pulls heat away from the body core to the surface
-hot water example
-skin may look pink/red
vasoconstriction
contraction of arrector pili to trap air and make insulation layer of smooth muscle in blood vessel of the skin to reduce blood flow to keep heat in
-cold water example
sensation receptors
senses the external environment (touch, pressure, vibration, temperature, and pain)
-picks it up and sends it to the CNS
