Skin Unit Flashcards
integumentary system
skin and its components (oil and sweat glands, hair and finger/toenails)
The skin comprises ____ to _____ of adult weight and covers area of _____ to _____ square meters.
15% - 20% of adult body weight
covers an area of 1.5-2.0 m²/18ft²
largest and heaviest organ of the human body
skin
Skin is challenged by….
radiation, pollution, injury, infection, dangerous chemicals and immune system attack
Doctors can learn ??? from our skin
clues about our general health
nutritional status, and disorders present such as liver cancer, anemia, diabetes and heart failure
The skin organ renews itself every ______ days
30 – 45 days
How is skin protection/barrier:
tothings permeating or losing things:
- microorganisms
- fluid loss/gain
- mechanical(friction contact, ex.clothes)
- chemical irritants
How does skin assist in temperature balance?
Temperature Balance Via fluid releases from sudoriferous (sweat) glands and reflexes of skin blood vessels
Skin is excretion medium for:
Fatty substances(oils)
H20
salts
vitamin residue
Uric acid
ammonia
How is skin involved in production of Vitamin D
via 7- dehydrocholesterol + sun exposure
liver and the kidneys as well will play a role in completion of this vitamin production process
Scientists starting to look at VitD more as a horemone – calcium absorption, and other roles
3 layers that make “skin
epidermis
dermis
hypodermis/ subcutaneous layer
epidermis structure
loose, flat, dry cells, condensed
dermis
loose and tough connective tissue, lots of organs (blood vessels, pain receptors, nerve receptors, tubular growths – hair follicles, thick to hold all stuff
subcutaneous or hypodermis
- made of adipose or fat tissue with blood vessels
- not considered part of the skin but helps to bind the skin proper to underlying muscle, bone organs and
- barrier to heat loss. It also stores lipid molecules which can be used to meet the nutrition and metabolic needs of the body
- aedopous tissue and blood vessels; binds to other tissues, keeps warm
The “true skin” is composed of
two kinds of tissue,the epidermis (flat dry cells) and the underlying dermis (loose and tough connective tissue)
The Epidermis is made out of 5 layers
Top-Down
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
Stratum corneum
1- uppermost layer
25 to 30 layers of dead heavily keratinized, nonliving scales, which become increasingly flattened as they approach the skin surface
slough off (desquamation)
new epidermis is produced every 30 -45 days (30 days up to 2 months)
Stratum lucidum
- 2nd layer from surface
- clear, translucent layer of flattened, non-nucleated (no organelles), dead or dying cells
- four to seven cells deep
Stratum granulosum
- 3rd layer from surface
- three to five cell layers filled with keratohyalin granules,(precursors of keratin)
- Keratin is a a tough, resilient protein that waterproofs/protects exposed skin surfaces
Stratum spinosum
4th layer
above stratum basale/ germinativum
cells with sharp pointed pieces coming off the cell to hold each other in place
5-Stratum basale (germinativum)
- at the very bottom
- “basale” means they are constantly going through cell cycling mitosis processing
- highly mitotic and produces continuous cells that move upward to the superior layers
- Melanocytes located here - produce a pigment called melanin that helps to color the skin/protect it from sun (genes determine melanin tones)
Basic Structure - Dermis
Layer under 5 layers of epidermis
Function: holds up epidermis and binds the epidermis to other tissues
thickest/busiest layer of the skin
primarily connective tissue, particularly collagen and elastic fibers in a gel – like substance
thickest and structurally busy layer of the skin
Contains: nerve fibers, sensory fibers/receptors, nail roots, erector pili muscles(goosebumps), hair follicles, sebaceous glands (oil) and sudoriferous glands (sweat glands)
blood vessels in dermis carry nutrients to upper layers of the skin and help regulate temperature
Damage and aging does what to skin?
dermis: (makes fewer cells) of these fibers causes wrinkling – loses taughtness which causes epidermis wrinkles
hypodermis:
Thins as we get older, this linked to wrinkling too, also cause sensitivity to temperature changes
How dermis helps regulate temperature
blood vessels in dermis carry nutrients to upper layers of the skin and help regulate temperature