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.