structures of the skin
Also known as cutaneous membrane
does more than it looks
functions
prevents loss of water
regulates body temp
sweating, dilation and constriction of blood vessels.
Helps make vitamin d
invlolved in sensory phenomena
barriers against microbial invaders
two main layers
The skin is about 6 ft in length
dermis
epidermis
tough leathery structure
made up of loosely packed cells, connecting protein fibers, small muscles, sweat glands, blood vessels, nerve endings, and hair follicles.
provided strength and flexibility and supports the growth of the covering epidermis
Bloodless
has 4-5 layers
each layer is made up of tightly packed cells
basal cells
adjoin the dermis, divide continuously, pushing their offspring toward the surface.
they absorb melanin.
epidermal cells also fill with a waterproofing protein called keratin
a hardened form of keratin forms nails, hair, and accessory organs
defensive cells
called dendritic cells, they phagocytize microbes that penetrate the deeper levels of the epidermis and then deliver microbial antigens to defensive lymphocytes.
Surface of the skin
Inhospitable environment covered with salt and sebum
sebum
oily lipid secreted by the sebaceous glands in the dermis
Between these two you get a barrier that acts as an antimicrobial
Hypodermis
Layer of fat cells and fibers beneath the dermis.
stored fat
provides energy
cushioning
insulation
anchor the skin to underlying tissue
Microbiome of the skin
Yeast and bacteria tolerate and even thrive in the cavities of the hair follicles and interiors of sweat glands.
Normal residents of the body
They compete proteinal pathogens for nutrients and space produce chemicals that interfere with he growth of other microbes.
scrubbing can reduce the number on the skin
Will not eliminate all, but most.
They grow in small clusters, and in areas of the armpits and between the legs where it is moister.
theor waste products produce odor
Malasseia
Member of the microbiome
it is a lipophilic yeast and they digest sebum
rarely pathogenic although it can cause disease in immune suppressed patients.
Gram positive bacteria also grows on the skin and can tolerate salt contraventions.
most common species on the skin would be staphylococcus epidermis.
Diptheroid
gram positive bacteria living on the skin
phlemographic bacilli are named for their appearence that is like corynebacterium diptheriae and are usually no pathogenic