Biggest Organ
Skin
- protects body from infection, extreme temps, balance of fluids and synthesizes vit d.
Epidermis
- composed of epithelial cells ( the outer most ) ( stratified squamous ) aka. multiple layers set on top of each other. ( like bricks )
- made up of keratinocytes
Dermis
- composed of dense connective tissues.
( sweating, circulating blood, feeling everything. )
- underlying ( the bulk of the skin )
Hypodermis ( Subcutaneous )
- composed of adipose / fatty tissues.
Integumentary System Consist of
Hair, Nails, Skin, Sweat, Oil glands.
4 different epidermis cell
- keratinocytes
- melanocyte
- dendritic cells ( langerhans cells )
- tactile epithelial cells. ( merkel cells )
2 /3 layers of the skin
- Epidermis
- Dermis
- Subcutaneous Tissue / hypodermis / superficial fascia " a bond " ( bc it wraps around the skeletal muscle ) ( not part of the skin )
keratinocytes
the building blocks of the tough fibrous protein keratin. -> ( gives structure, durability, and waterproofing to everything )
Keratin Cell
- found in epidermis
- constantly dies and gets replaced.
- loses a million everyday
4-6 weeks it will get replaced.
- arise from the deepest part of skin ( stratum basale )
Melanocyte
- another epidermal cell
- synthesizes melanin -> ( gives pigment skin its color )
- shaped like a spider
Dendritic Cells ( Langerhans Cells )
- kinda star shaped
- originate in bone marrow then migrate to the epidermis.
- ingest foreign substances.
Tactile epithelial cells. ( merkel cells )
- A combine with nerve endings to create a sensory receptor for touch.
- spiky hemisphere ( blue cell )
Cellular Extensions
the reason why people have different skin colors. which affect the amount of melanin they contain.
Thick / Thin Skin
Thick : tougher parts of the palms of hands, and soles of feet with consisting of 5 epidermal layers.
Thin : everything else with 4 layers. ( does not have stratum lucidum )
5 layers of epidermis
- stratum basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum Corneum
Statum Corneum
- " horny layer "
- the outermost layer and roughest
- 20/30 bed sheets of ke
Stratum Lucidum
- "clear layer "
- 2/3 rows of flat dead keratinocytes.
Stratum Granulosum
- more serious layer bc it contains living keratinocytes that are forming keratin like crazy
- Cells matures as they go up to the layers.
Avascular
Oxygen and nutrients comes from the dermis below.
Stratum Spinosum
- cells looks prickly when dehydrated
-
Stratum Basale
- Deepest and thinnest epidermal layer
- single layer of columnar cells but like cell factory due to new-cell production
- layer that connects to epidermis and dermis.
Pneumonic for the layers
Come lets get sunburn
Dermis function
collagen & elastic fibers
- with capillaries, blood vessels and nerve fibers ( temperature , pressure and sweat glands, oils, hair follicles. )
Dermis has 3 layers
- Upper ( Papillary ) thin sheet of areolar connective ( papillae )
Friction ridges ( in order to grip things )
- Reticular Layer ( 80% ) made up of dense irregular tissues. ( bleed and feel pain )
- Basal layer. ( hypodermis ) adipose connective tissues ( seam of fat )
- insulation, energy storage, shock absorption and helps anchor the skin.