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22 Cards in this Set

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Skin is the largest organ system. It covers 20 sq feet on an average adult.

- What are the two main layers and third one?
- Epidermis
- Dermis
- Subcutaneous (adipose tissue)
* Epidermis layer:
thin but tough - makes a rugged protective barrier.

- What are the many stratified layers?
- Stratum germinativum (inner/basal layer)
- Stratum corneum (outer horny cell layer)
* Stratum germinativum
(inner epidermis layer)
- forms new skin cells
- Major ingredient: tough, fibrous protein keratin
- Melanocytes produce pigment melanin --> gives brown tones to skin and hair

- Compare/contrast melanocytes in people?
- People all have the same number of melanocytes --> but the amount of melanin produced varies --> genetic, hormonal, environmental influences
* Stratum corneum
(outer epidermis layer)
- Consists of?
- dead keratinized cells (interwoven and closely packed)
- consistantly being shed (desquamated)
- replaced with new cells from below, completely every 4 weeks
Epidermis is ___________, and nourished by blood vessels in the dermis blow.
- Avascular
Skin color is derived from what three sources:
(1) mainly from the brown pigmetn melanin
(2) yellow-orange tones of the pigment carotene
(3) the red-purple tones underlying vascular bed
Skin color is affected by three things:
(1) relative proportion of shades (brown, red, yellow)
(2) thickness of skin
(3) presence of edema
* Dermis layer:
- The inner layer composed of connective tissue or collagen
- Tough, fibrous protein --> enables skin to resist tearing
- Resilient elastic tissue --> allows skin to stretch with body movement
What four structures lie within the dermis?
- nerves
- sensory receptors
- blood vessels
- lymphatics
What three appendages from the epidermis are also embedded in the dermis?
- hair follicles
- sebaceous glands
- sweat glands
* Subcutaneous layer:
- Adipose tissue, made up of lobules of fat cells
Subcutaneous layer stores fat for:
- energy
- insulation for temperature control
- aids in protection by its soft cushioning effect
The loose subcutaneous layer gives skin an __________ mobiity over structures underneath.
- increased
Epidermal appendages are formed by tubular invagination of the ________ down into the underlying __________.
- epidermis
- dermis
Hair is _________ for humans.

- no longer needed for protection from cold or trauma --> little or no use/from ancestors
- vestigial
* Vellus hair:

- Does not cover which parts of the body?
(epidermal appendage)
fine, faint hair covers most of the body

- palms, soles, dorsa of the distal part of fingers, umbilicus, glans penis, inside labia
* Terminal hair:
(epidermal appendage)
- darker, thicker hair
- grows on: scalp, eyebrows, after puberty on axillae, pubic area, face and chest on males
* Sebaceous glands:
(epidermal appendage)
- produce protective lipid substance, sebum --> secreted through hair folicle
- sebum oils/lubercates skin and hair --> forms emulsion with water that retards water loss from skin
- Everywhere but palms/soles
- Most abundant: scalp, forehead, face, chin
* Sweat glands (2):
(epidermal appendage)
- eccrine gland
- apocrine gland
* Eccrine:
(epidermal append: sweat gland)
- coiled tubules --> open directly onto skin and produce dilute saline solution, sweat
- mature in 2 month old infant
* Apocrine:
(epidermal append: sweat gland)
- produce thick, milky secretion --> open into the hair follicle
- mostly in the auxillae, anogenital area, nipples and naval (vastigial in humans)
- acitve during puberty, emotional, sexual stimulation
- bacteria flora --> musky body oder on surface of skin
- decreases function in aging adult
* Nails:
(epidermal appendage)