The Integumentary System Anatomy Open Stax

Skin

The largest organ in your body, there are 3 layers

What are the 3 layers of skin?

Epidermis, Dermis & Hypodermis

Epidermis

A lot of epithelial cells here, it can be broken down into 5 layers

Dermis

Hypodermis

Deepest layer, mostly (adipose)fat connective tissue, major function is to "connect what's underneath"

What are the 5 layers to the Epidermis?

Stratum: Basale, spinosum, granulosum, lucidum & corneum

Keratin

A protein found in the skin, it helps waterproof and add strength, it's stratified, has several layers and squamous in shape

Keratinocytes

Produces keratin (protein)

Basal cell

It's a cell that is "replicating"

Melanocytes

Cells that produce "melanin", melanin is a protein pigment protecting UV rays

Merkel cells

Associated with the Nervous System, "sensory touch receptors"

Langerhans

Macrophages, also known as "wondering phagocytes"

Stratum Basale

The "bottom" layer of the epidermis, this layer produces new epithelial cells, it's biggest feature is that it's "mitotic" and produces new cells

Stratum Basale contains what cells?

Basal cells, Melanocytes & Merkel Cells

Merkel cells

Sensory endings

Stratum Spinosum (Prickly layer)

A lot of cell connections here (desmosomes), there are also Langerhans cells and melanosomes here

Stratum Granulosum (Granular Layer)

All cells are starting to die and disintegrate here in this layer, they are starting to flatten, "a cell membrane and nucleus is all that is left here"

Stratum Lucidem (clear layer)

Found in thick skin, dead skin cells, it's found in two locations on our body in the soles of our feet and palms of hand

Eleiden

Part of the stratum lucidem, it's "some of the components left behind"

Stratum Corneum (Horny Layer)

Many layers of epithelium cells, it's function is to provide a barrier to infection and injury, it takes about 2 weeks from the bottom to reach the top

Dermis

Still have macrophages helping with immunity, there are 2 layers papillary and reticular, contains nerve fibers, blood vessels and lymphatic vessels, contains oil and sweat glands

What are the 2 layers of the Dermis?

Papillary & Reticular

Dermis: Papillary Layer

More towards the top, mostly connective (areolar) tissue, this layer molds our fingerprints in our fingers

Dermis: Reticular Layer

No longer wave like appearance like the papillary layer, it's an "irregular" pattern, dense irregular tissue here

What are the 3 pigments that contribute to skin color?

Melanin, Carotene & Hemoglobin

Melanin

"How much" and "what type" of this being produced is a key factor, it's major function is shielding keratinocytes, this is where your tan comes from

Carotene

Found in the "hypodermis", a yellow orange color

Hemoglobin

Found in "red blood cells", this does change color if "oxygen" is attached to it

Erythrocyte

A fancy name for a red blood cell

Hair: Shaft

Anything "above" skin

Hair: Root

Anything "below" skin

Hair: Follicle

The structure that holds the hair down into the dermis

Hair: Bulb

Referring to the "deepest" part of the hair, growth happens in this area

Hair: Arrector Pili

Connects to our hair follicle, "smooth muscle" meaning it's involuntary controlled, when it contracts your hair stands up straight (goosebumps)

Hair: Matrix

Deepest portion within hair bulb, new cell growth happens here

Hair: Papilla

Look at diagram, our blood system that provides connection

Nail: Matrix

Where we create new cells, it's within the root towards the base of the nail

Nail: Lunule

Really thick area of the nail

Nail: Body

The majority of the nail

Nail: Free edge

Part of the nail that hangs off the finger

Nail: Cuticle

Also called the "Eponychium",

Sweat glands are referred to as?

Sudoriferous Glands

What are the 2 main types of Sweat Glands?

Eccrine & Apocrine

Eccrine Sweat Gland

Found "all over the body", they produce sweat due to thermoregulation, it cools you down

Apocrine Sweat Gland

Only find them in your armpits and groin regions, "milky sweat" meaning it has more fat to it, it's the sweat gland that produces the smell

Sebaceous Gland

Typically have their own sweat pore, not connected to hairs, sebum is an oily substance

What are the main functions of the Integumentary System?

Protection, sensory function, thermoregulation, vitamin D synthesis & excretion

Form of protection for integumentary system?

Nails and end of fingers

Sensory function of integumentary system?

Merkel cells

Thermoregulation of integumentary system?

Sweat glands and hair

Vitamin D of integumentary system?

If exposed to UV rays, 20 minutes causes stimulation creating this vitamin in your cell, "for the absorption of calcium" we need this vitamin

Excretion of integumentary system?

Within sweat we do have lactic acid, getting rid of through skin

Skin cancer

Most skin tumors are benign (not cancerous) and do not spread

Basal cell carcinoma

This originates in basal layer of epidermis, it's the least dangerous, but most common in people

Squamous cell

Keratinocytes are involved, it DOES spread

Melanoma

Cancer in melanocytes, the MOST dangerous

First degree burns

If it only penetrated the first layer of tissue (epidermis), example is sunburn

Second degree burns

Penetrated into the "dermis" example is blistering to the area

Third degree burns

Penetrated into the hypodermis

How do we assess burns?

The rule of nines