1. THE INTEGUMENTARY SYSTEM
The Skin and its Appendages

2. Functions of the Skin
PROTECTION – from injury, chemicals, temperature, and bacteria
PREVENTS water loss by producing KERATIN – a water proofing protein
REGULATES body temperature
EXCRETES excess water and salt
PRODUCES vitamin D
SENSES our environment

3. STRUCTURE OF THE SKIN
EPIDERMIS – outer layer composed of stratified squamous epithelium
DERMIS – located directly below the epidermis – composed mostly of dense connective tissue
SUBCUTANEOUS or HYPODERMIS – located below the dermis – composed mostly of adipose tissue

4. STRUCTURE OF THE EPIDERMIS
COMPOSED OF FIVE LAYERS (STRATA)
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale

5. EPIDERMIS LAYERS (STRATA)
STRATUM BASALE
Receives the most adequate nourishment because it is closest to the dermis
Constantly undergo mitosis
Daughter cells are pushed upward closer to the skin’s surface and away from nutrition
Also called stratum germinativum

6. EPIDERMIS LAYERS (STRATA)
STRATUM SPINOSUM and STRATUM GRANULOSUM
Cells become increasingly flat and full of keratin.
STRATUM LUCIDUM
layer in which cells die – only found where skin is hairless and extra thick – palms of hand and soles of feet

7. EPIDERMIS LAYERS (STRATA)
STRATUM CORNEUM
20 to 30 cell layers thick
Cells are completely dead and fully keratinized
Creates hard layer that protects cells underneath
Average person loses 40 lbs. of this layer in their lifetime!
Replaced by cells of stratum basale every 25 – 45 days.

8. MELANOCYTES Specialized cells found primarily in the stratum basale
Produce the pigment known as MELANIN – ranges in color from yellow to brown to black
Production is stimulated by sunlight
Freckles and moles are seen where melanin is concentrated in one area.
Melanin production is genetically determined.

9. STRUCTURE OF THE DERMIS
PAPILLARY LAYER
Upper dermal region
Has projections called PAPILLAE which indent the epidermis above
Papillae of hands and feet are arranged in definite patterns – these form fingerprints
Layer that houses touch ( Meissner’s corpuscles) and pain receptors (free nerve endings)
Papillary layer

10. STRUCTURE OF THE DERMIS
RETICULAR LAYER
Deepest skin layer
Contains blood vessels, sweat, and oil glands
Has deep pressure receptors called Pacinian corpuscles
Contains collagen which gives skin its strength
Contains elastic fibers which give skin elasticity or “stretchiness”
Reticular layer

11. SKIN COLOR PIGMENTS
Amount of MELANIN – ranges from yellow to brown to black
Amount of CAROTENE – a yellow-orange pigment found in foods like carrots – the body deposits it in stratum corneum and subcutaneous layer
Amount of HEMOGLOBIN – blood pigment that shows through from the dermal capillaries

12. SKIN APPENDAGES SEBACEOUS GLANDS
Produce oils (sebum) that keep skin moist and soft
Prevent hair from becoming brittle
Sebum contains chemicals that kill bacteria
Sebaceous gland

13. SKIN APPENDAGES SWEAT(SUDORIFEROUS) GLANDS
ECCRINE sweat glands secrete primarily water and empty from pores distributed on the body’s surface
APOCRINE sweat glands are primarily in the axillary and genital regions and secrete into hair follicles – associated with body odors
Sweat glands

14. SKIN APPENDAGES
HAIR
Produced by an EPIDERMAL structure called the hair FOLLICLE
Composed of three layers: medulla, cortex and cuticle
The cuticle is formed by highly keratinized, dead epithelial cells.
The arrector pili muscle attached to the hair follicle are the cause of “goose bumps”
Hair Structure
Medulla (core)
Cortex
Cuticle

15. SKIN APPENDAGES
NAILS
Modification of the epidermis having a free edge, body (visible attached portion) and root (embedded in skin)
Heavily keratinized and colorless – appear pink because of blood supply below.
Grows from the nail bed or matrix

16. BURNS
BURN – damage or cell death caused by heat, electricity, radiation, or chemicals
1st Degree – only the epidermis is damaged
2nd Degree – damage the epidermis and upper region of the dermis – blisters are likely
3rd Degree – entire thickness of the skin is destroyed – regeneration isn’t possible – skin grafts must be done to replace damaged tissue

17. SKIN DISORDERS
ATHLETE’S FOOT – itchy, red, peeling condition between toes – caused by a fungus
COLD SORES – fluid filled blisters that itch and sting – caused by herpes simplex virus – activated by upset, fever, or UV light
PSORIASIS – chronic condition producing too many skin cells – believed to be an autoimmune condition in which the immune system attacks a person’s own tissues.
ACNE – condition caused by over-production in the sebaceous glands – prevalent in teens because of hormonal changes

18. SKIN DISORDERS SKIN CANCERS
Basal Cell Carcinoma – least malignant and most common – appear as lesions in areas that have been exposed to a lot of sun – relatively slow growing
Squamous Cell Carcinoma – appears as a scaly, red lesion – eventually forms an ulcer on the surface of the skin – appear most often on scalp, ears, and lips – also believed to be sun-induced.

19. SKIN DISORDERS SKIN CANCERS
Melignant Melanoma – begins wherever there is pigment – appear spontaneously or where there is existing pigment
DIAGNOSIS
Asymmetry
Border irregularity
Color
Diameter
Elevation