Integument

Skin/cutis

is an organ made of epidermis and dermis

Integument

Organ system: epidermis, dermis, and hypodermis

Functions: keeping the bad out, waterproofing (keeping the good in), protection against abrasions, sensory, exchange, fat metabolism, utilizing UV, and sociosexual communication

Epidermis

The uppermost, avascular layer of the skin/cutis

• made of stratified squamous epithelial cells

Dermis

The lower, vascular layer of the skin/cutis

• mostly made of dense irregular connective tissue

Stratum Basale (germinativum)

• mitotic spindle (purple in the middle)

  • allows the cell to continue to split and replicate

• keratinocyte (pink “blocks”)

  • new cell being produced to go up and push the layers upward

  • create and hold onto keratin, a tough protein

• melanocyte

• Functions

  • cell division

  • UV protection

Melanocyte

Little brown guy that lives on the stratum basale layer. Reaches his arms out to new keratinocytes that bite off bits of melanin.

• darker skin = more active melanocytes (freckles too, except locally)

• moles = local proliferations of melanocytes

• melanin protects the nucleus of cells from UV to prevent mutations (cancer)

Stratum spinosum

• avascular, no replication

• main job to create keratin —> toughness of the epidermis

Stratum granulosum

cells are beginning to die —> getting spiny and shrinking —> leaking lipids and fats

• leaked lipids fill the gaps between the cells, creating the waterproofing layer to keep all of the liquid inside of our bodies

Stratum lucidum

ONLY on palms and soles of the feet

• is a sublayer of the stratum corneum

• is a clear, thick layer

Stratum corneum

Overall outermost layer of the skin

• really thin layer

• completely dead cells —> only left keratin

• function: protect against abrasions

the life of a skin cell is approximately ________ from birth to death.

3 months

Strata

uppermost layer of the dermis

• loose connective tissue

• has dermal papilla

Dermal papilla

• look like little fingers

• has grooves like fingerprints

• has protrusions to increase surface area

Function: blood and nutrient transfer

Reticular layer (stratum reticulare)

dense irregular connective tissue

function: creating cleavage lines for the dermis to tear on

Hypodermis (subcutaneous tissue)

• adipose & loose connective tissue (vascular)

  • there can be more or less of either

Strata

Bottom layer of skin in the hypodermis

• fatty layer

  • Reticulum cutis anchors the fatty layer with fibers (collagen)

• fibrous layer

  • thin layer of dense irregular connective tissue

Hair follicle

follicular wall:

• stratified squamous epithelial tissue

grows from the bottom of the follicle where the nutrients are, and pushes dead keratin up

parts of the hair shaft

Inside to outside:

• medulla

• cortex

• cuticle

Arrector pili muscles

• smooth muscle

• makes goosebumps for temp regulation

material of all glands

simple cuboidal epithelium

Sebaceous holocrine gland

• sits on every hair follicle

• secretes sebum

Eccrine sweat or sudoriferous gland

• opens onto the skin

• is everywhere you have skin

• secretes normal sweat

Apocrine sweat or sudoriferous gland

• short tube with fat coil

• attaches to certain hair follicles

  • only in the armpits, genital, and anal regions

• secretes proteinaceous sweat (pheromones)