Superficial layer of epitheleal tissue

Keratinized stratified squamous

Layers of Epidermis

(deepest to surface)

1. Stratum basale

2. Stratum spinosum

3. Strum granulosum

(4. Stratum Lucidum- only in feet and palms)

5. Stratum corneum

Cells of the Epidermis

1. Karatinocytes

2. Melanocytes

3. Dendritic or Langerhans cells

4. Tactile or Merker cells

Skin (Integument)

composed of 3 layers

Epidermis

Dermis

Hypodermis or Subcutaneous Layer

Keratinocytes

- Procuce the protein Keratin

- Most cells of the epidermis

-Tightly connected by desmosomes

Melanocytes

- Deepest epidermis (Statum Basal)

- Produce pigment Melanin

- Protect keratinocyte nucleus form uv damage

Dendritic (or Langerhans) Cells

-Macrophages - immune system

(eat up foreign matter)

Tactile or Merkel Cells

-Sensory touch receptors

- in Stratum Basal layer

Dermis

- Mostly dense irregular connective tissue

- Fibroblast cells (make collegen and elastic fibers)

-Fibers in matix

- contain nerve fibers, blood and lymphatic vessels

-Contains epidermal hair follicles, oil + sweat glands

-Two layers

*Papillary (smallest)

*Retiular (most)

Papillary Layer of Dermis

-Areolar connective tissue with collegen and elastic fibers and blood vessels

- Loose tissue

- very thin top layer that makes your fingertips

Dermal Papillae Layer of Dermis

-Superficial peg or wavelike projections

-creates ripples in your skin, ie. fingerprints pushes out the paillary layer

Reticular Layer of Dermis

-Most of the dermal layer

- Dense irregular connective tissue

- Elastic fibers(stretch and recoil)

-Collagen fibers (strength, resiliency and waterproofing)

Skin Color

- Melanin (whites to blacks)

- Carotene (yellow/orange)

-Hemoglobin (red)

Melanin

-Reddish yellow to brownish black

-Produced in melanocytes

-forms pigment shields in the keratinocytes nucleus

- Freckles and moles

-Sun stimulates production

Carotene

- Most obvious in palms and soles

-Accumulates in stratum corneum and hypodermis

-Converts to vitamin A

Hair Follicles

-Extend from epidermal surface to dermis

-2 layer wall - parts dermis/epidermis

-Hair Root

-Arector Pili (smooth muscle attached to follicle)

-Hair Shaft (above skin)

Nails

-Scalelike epidermis

-Protective covering for fingers and toes

-Contain hard keratin

-NO melanin

Sweat or Sudoriferous Glands

-all skin surfaces except nipples and exernal genitalia

-3 million per person

-Two main types

*Eccrine

*Apocrine

Eccrine Sweat Glands

-Most numerous

-Abundant on palms, soles, and forehead

-Ducts connect to pores

-Thermoregulation - regulated by sympathetic nervous system

-Secretion is sweat

Appocrine Sweat Glands

-Auxillary and genital areas

-Sweat + fatty substances +protiens

-Larger than eccrine glands

-Ducts empty into hair follicles

Begin functioning at puberty

Modified apocrine glands

*ceruminous glands (ear wax)

*Mammary glands (milk)

Sebaceous (oil) Glands

-Everywhere BUT palms and soles

-Secrete into hair follicles

-Inactive until puberty (stimulated by hormones)

-Secrete sebum (oily, bacterial, softens hair and skin)

Basal Cell Carcinoma

-Least mailgnant/most common

-Stratum basale cells proliferate and invade dermis and hypodermis

-Cured by surgery in 99% of cases

Squamous Cell Carcinoma

- 2nd most common type

-Involves keratinocytes of stratum spinosum

-Usually scaly reddened on scalp, ears, lover lif and hands

-Does metastisize

Good prognosis if treated with radiation or surgery

Melanoma

-Cancer of melanocytes

-Most danerous! metastic and chemo resistant

-Treated by surgery and immunotherapy

Early detection:

*Asymmetry

*Border

*Color

*Diameter

1st Degree Burn

-Epidermal damage only

redness, swelling and pain

2nd Degree Burn

-Epidermal and upper Dermal damage

*Blisters

3rd Degree Burn

-Entire thickness of skin

*skin gray/white, cherry red or blackened

*Not painful as nerve endings are destroyed

*Skin grafting is usually necessary