Transcript 5 Unit 1 - Cloudfront.net

The Integumentary System 5
Unit 1
Chapter 5
Integumentary System
The Body Covering
Includes: skin, nails & hairs
Skin = cutaneous membrane
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Two main parts =
Epidermis- surface epithelial layer
Dermis -deeper connective tissue
layer
Deep dermis not part of the skin =
subcutaneous layer or Hypodermis
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Structure
Figure 5.1
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Keratinized stratified squamous
epithelium
4 cell types:
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells
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Epidermis
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Keratinocytes
90% of epidermal cells
4-5 layers
Produce keratin
Protect skin
Waterproof skin
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Epidermal Cells
Epidermal Cells
Melanocytes - produce melanin
Transfer pigment to keratinocytes
8% of epidermal cells
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Epidermal Cells
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Langerhans Cells- immune
response
Merkel cells – sensory
Include tactile disc and neuron
= touch sensation
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Epidermal Layers
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Generally 4 strata (layers)
Stratum basale –includes stem cells
Stratum spinosum – 8-10 cell layer
Cells beginning to look flattened
Stratum granulosum –keratin
Losing cell organelles and nuclei
Include lamellar granules = waterproofing lipid
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Stratum corneum – flattened dead
cells
Cells shed and are replaced from below- mostly keratin-filled
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Skin Color
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Melanin- dark color
Darkness depends on amount of melanin
produced.
gives some protection against UV
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Carotene- yellow orange
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Hemoglobin in blood- pink-red
Depends on blood flow
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In stratum corneum and adipose layers-
Accessory Structures
Hair
Skin glands
Nails
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Hair
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Found on most skin surfaces
Not on palmar surfaces of hand and fingers or plantar
surfaces of feet
Made of fused keratinized cells
Consists of shaft & root
Surrounded by hair follicle
Base is bulb which includes growing matrix producing cells
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Nerves- hair root plexuses
Muscle- arrector pili
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Figure 5.3
Glands
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sebaceous gland- secrete oily sebum
Connected to hair follicles
sudoriferous or sweat gland
Eccrine sweat gland
Wide distribution- thermoregulation
apocrine sweat gland
Axilla, groin, areolae, beard
Contain other cell material and produce pheromes
Ceruminous Glands- external auditory
canal
Combine with sebum to produce earwax
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Plates of packed hard dead
keratinized cells
Nail body- major visible portion
Free edge- part extending past
finger or toe
Root – part not visible
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Nails
Figure 5.4a
Figure 5.4b
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Temperature Regulation
Protection
Sensory reception
Excretion & Absorption -small
Vitamin D synthesis
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Functions
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Adolescence- can develop acne
Mostly dermis- visible ~ age 40
Loss of collagen fibers
Loss of elasticity
Loss of immune responses
Decreased melanocyte functionsgray hair, blotches
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Thinning
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Aging