Skin functions
Function:
-protective covering to prevent the entry of microorganisms into the body
-regulates water loss from underlying tissues
-regulates body temperature
Keratin
provides waterproofing so internal tissues retain their water, and skin absorbs minimal water from the environment and provides toughness against wear and tear
Benefit of UV rays on skin
produce vitamin D in response to sunlight which is essential for strong bones and teeth.
The skin contains
Contains:
-sensory receptors (for touch, pressure, pain) -sweat glands (helps regulates fluid balance, temperature and release wastes)
-Keratin
-melanin
Melanin
-protein that filters and blocks the UV rays from penetrating through to the DNA
- brown pigment that provides protection from UV
how does skin help regulate body temp
-blood vessels in the skin can constrict to conserve body heat and dilate to release it
-sweat is released to cool the skin as energy is used for sweat evaporation
-shivering of the muscles under the skin generates heat in cold conditions
what are the three layers of skin and what are the two main layers
outer epidermis (main layer), inner dermis (main layer), and hypodermis
Epidermis
- composition
-vascular or avascular
-how does nutrients arrive and wastes leave
- composed of stratified squamous epithelium
-avascular
-nutrients arrive and wastes leave by diffusion with the underlying dermis
What are the two layers of connective tissue of the dermis
- papillary layer
- reticular layer
papillary layer
-superficial or deep
-connected to what
-composition
- superficial layer
-connected to the epidermis
-composed of loose areolar connective tissue
Reticular layer
-superficial or deep
-composition
-deep layer
-composed of dense irregular connective tissue
what do the blood vessel do in the dermis
they supply the epidermis with nutrients and to remove wastes
Hypodermis
- what type of tissue
- contains what
- loose connective tissue with scatter adipocytes
-contains the main blood vessels that send branches into the dermis to supply the skin
how many layers does the epidermis contain
- 5 layers in places like the soles of the feet
-4 layers in most areas of the body
Stratum corneum
- location
-compostion
- outer most layer of the epidermis
- tough, dead, tissue layer formed from sheet of highly keratinized cells connected by desmosomes
Stratum lucidum
-location
-composition
-can be found where
- 2nd most outer layer of the epidermis
- layer of clear keratinized cells
-found in the thick skin of the palms, soles and in calluses
Stratum granulosum
-location
-composition
- dead or alive
-shape
- middle epidermal layer
-keratinization accumulation occurs as granules - alive
-flat
Stratum spinosum
-location
-composition
- dead or alive
- second deepest epidermal layer
-contain active keratinocytes (produces keratin)
-contains immune cells that patrol for infectious and abnormally dividing cells
-alive
Stratum basale
-location
-function
-attaches to what
-composition
-deepest epidermal layer
-actively dividing and producing new cells to replace other layers
-attaches to the basement membrane
- contains Merkel cells (sensitive to touch)
what produces melanin
melanocytes within the stratum basals layer of the epidermis
Albinism
unable to produce melanin within their melanocytes through the body causing them to be very pale and susceptible to skin cancer
Vitiligo
lack of melanin production in limited locations causing two different color skin
Basal cell carcinomas
- most common type of skin cancer
-originates in the stratum basal and results from mutation caused by over exposure to sunlight
Malignant melanomas
-more serious form of skin cancer
-ordinate in the melanocyte cells resulting in the dark patch appearance
