5-1. The Skin Flashcards
Integumentary System
the skin and organs derived from it, including hair, nails, sweat and oil glands
What are the 5 functions of the integumentary system?
- protection
- regulation of body temperature
- cutaneous sensation
- Vitamin D conversion
- Excretion
What does the integumentary system protect from?
protects underlying tissues from physical abrasion, bacterial invasion, and damaging UV radiation
What does the integumentary system use to regulate body temperature?
sweat glands, shivering, blood flow to surface
cutaneous sensation
special receptors that detect temperature, touch, pressure, and pain
When skin is exposed to sunlight, __ in dermal blood vessels is converted to a __.
modified cholesterol; Vitamin D precurser
What does the skin excrete?
small amounts of nitrogenous wastes (ammonia, urea, uric acid) are eliminated in sweat (though they are mostly excreted in urine)
The skin is the __ organ in the body.
largest
What are the two main layers to the skin?
epidermis (outer, thinner layer), dermis (inner thicker layer making up the bulk of the skin)
outer, thinner layer of the skin
epidermis
inner thicker layer of the skin, making up the bulk
dermis
What are the functions of the epidermis?
protects, waterproofs, adds new cells, gives rise to hair, nails and glands
What is the general structure of the epidermis?
keratinized, stratified squamos epithelium organized in 4-5 layers
The epidermis is ___. (vascular/avascular)
avascular - nourishment comes from underlying dermis
keratin
fibrous protein produced by keratinocytes that waterpoofs skin, resists abrasion, and acts as barrier to bacteria
keratinocytes
special epidermial cells producing keratin
What are the five epidermal layers, from deep to superficial?
stratum basale stratum spinosum stratum granulosum stratum lucidum stratum corneum
“Bring Some Good Lotion to Cover”
stratum basale
deepest layer of epidermis, attached to dermis. 1 layer of cells that keeps making new cells by mitosis
What is the only layer of the epidermis that divides?
stratum basale
Where is the stratum lucidum found?
thick skin of palms/soles
stratum corneum
thick outer layer of flat dead cells filled with keratin and continuously shed
keratinization
newly formed cells from basal layer are pushed to surface > filled with keratin and die (too far from blood vessels) > flake up and replaced from below
We get a new epidermis every ___.
25-45 days
callus
a thickening of the epidermis caused by persistent friction
What are the functions of the dermis?
nourishes and supports epidermis, contains nerves for touch, gives skin strength, elasticity and extensibility
What is the general structure of the dermis?
dense connective tissue containing collagen and elastic fibers. Permeated by many blood vessels, nerves, glands and hair follicles.
What are the two layers of the dermis?
papillary and reticular
The papillary layer is made of ___.
areolar connective tissue
dermal papille
found on superior surface of the papillary layer; project into epidermis and contain capillaries or nerve endings. Increase friction and cause fingerprints.
reticular layer
thick, deeper layer of the dermis (~80% of dermis), made of dense connective tissue
hypodermis
subcutaneous layer of mostly adipose tissue, just deep to skin
What are the functions of the hypodermis?
Attaches the dermis to underlying organs (muscle and bone), acts as a shock absorber, insulator and area of fat storage
striae
stretch marks caused by extreme stretching of the skin
blister
separation of dermal and epidermal layer by a fluid filled pocket, from short term acute trauma
What determins skin color?
3 pigments: melanin, carotyne, and hemoglobin
melanin
ranges in color from yellow to reddish brown to black. Absorbs UV radiation from sun. Racial differences due to type and amount of melanin.
sun tan
prolonged sun exposure causes buildup of melanin to protect cell DNA from UV radiation
albinism
inherited inability to make melanin
Local accumulations of melanin are called __.
freckles (flat) or moles (raised)
melanocytes
cells in epidermis that make melanin
carotine
yellow-orange pigment in certain plants that tends to accumulate in the stratum corneum and hypodermis. Most obvious in palms and soles, varies with diet.
hemoglobin
red pigment in blood cells circulating in capillaries of dermis
cyanosis
blue; low oxygen
erythema
red; inflammation, allergy, fever, emotion
pallor
white; stress, low BP, anemia, fear or anger
jaundice
yellow; liver disorder
bruises
black and blue; blood escapes from damaged vessels and clots beneath skin
vitiligo
loss of melanocytes (autoimmune)
