Two divisions are
Epidermis
Dermis
Epidermis
On top
Dermis
Bottom layer
Deep to skin
Hypodermis (superficial fascia)
Epidermis is composed of
keratinized stratified squamous epithelium
Keratin- waterproofing protein
Cells of the Epidermis
Keratinocytes
Melanocytes
Merkel cells
Keratinocytes
Cells that produce keratin
Melanocytes
Cells that produce melanin
Merkel cells
Touch receptors
Epidermal Layers(listed deepest to superficial)
Stratum basale (germinativum) Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum
Stratum lucidum is only found in
thick skin (palmar and plantar regions)
Stratum corneum
Constantly
sheds cells from here
All cells above this layer are dead because there are no blood vessels
Stratum granulosum
Dermis is mainly
dense irregular CT
Two layers of the dermis are
2 layers - papillary and reticular
Papillary layer
1.Superficial region
- Dermal papillae contain capillaries & tactile (Meissner’s) corpuscles
- lightest touch to respond
3.Dermal ridges present on palmar & plantar regions
Reticular layer is the
Deeper part of dermis
Hypodermis is
Subcutaneous layer (deep to the skin)
Hypodermis is composed of
mostly adipose CT
Hypodermis attaches
skin to underlying muscle
Hypodermis gets thicker when
you gain weight/age
Reticular layer accounts for
approximately 80% of the thickness of the skin
Reticular layer Contains
lamellated (Pacinian) corpuscles
-Takes more pressure to respond
Three pigments contribute to
Skin color
The 3 pigments are
Melanin
Carotene
Hemoglobin
Attributes of melanin
Darkest
Freckles and pigmented moles
Easiest broken down in caucasion people
Attributes of Carotene
Orange
Found in orange foods
Attributes of Hemoglobin
Blood supply
Embarrassment - reason why your face turns red
Glands contained in the integument
Sweat (sudoriferous) glands
Ceruminous glands
Mammary glands
Sebaceous (oil) glands
Sweat (sudoriferous) glands function
Secrete sweat to cool you down
Ceruminous glands function
Secrete wax in ears
Mammary glands function
Secrete milk during lactation
Sebaceous (oil) glands function
Secrete sebum (oil) ~ sebum is acidic and that helps decrease the numbers of bacteria on the skin
Functions of integument
Protection
Sensation
Produces vitamin D in presence of sunlight
Thermoregulation
Occurs Cutaneous vasoconstriction
During thermoregulation
Skin vessels constrict
Less blood gets to this area which means the blood is maintaining the normal body temperature - maintain heat to stay warm
Occurs during Cutaneous vasodilation
During thermoregulation
Skin vessels enlarge
Allows more blood to flow through and allow heat to be lost
Arrector pili
Muscle that is attached to the hair follicle
When muscle contracts
hair stands up and gives you goose bumps
Preview of what’s to come: Old Age
Regeneration slows (skin becomes thinner)
Intolerance of cold
Wrinkles
Increased risk of skin cancer
Increased risk of skin cancer because
decreased number of melanocytes
Only epidermis is damaged
First degree burn
Part of the dermis (papillary layer)
Ex: blisters
Second degree burn
Third degree burn
Entire thickness of the skin including the hypodermis
No pain because the nerves were burnt, the pain would be coming from the second degree
Skin grafts needed
First threat to life
Fluid loss
Dehydration
Second threat to life
Infection
Desmosomes
tight cell junctions prevent skin from tearing
Rapid spread of cancer tissue to another tissue
Metastasis
