5-1 lecture 5 integumentary system. 5-2 integumentary system consists of: 1.skin (epidermis &...
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5-1
Lecture 5
Integumentary System
5-2
Integumentary System• Consists of:
1. Skin (Epidermis & Dermis)
2. Accessory structures• Hair• Nails• Glands
• Functions– Protection– Sensation– Temperature regulation– Vitamin D production– Excretion
Fig. 5.1
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Epidermis and Dermis
Fig. 5.2
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Epidermal Cells• Cell types
– Keratinocytes: Produce keratin for strength
– Melanocytes: Contribute to skin color (pigment melanin)
– Langerhans’ cells: Part of the immune system
– Merkel’s cells: Detect light touch and pressure
•Keratinization: Cells die and produce outer layer that resists abrasion and forms permeability layer
Fig. 5.2
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Epidermal Strata• Stratum Basale
– Deepest portion of epidermis and single layer
– High mitotic activity
• Stratum Spinosum– Limited cell division
• Stratum Granulosum– In superficial layers
nucleus and other organelles degenerate and cell dies
Fig. 5.2
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Epidermal Strata• Stratum Lucidum
– Thin, clear zone
• Stratum Corneum– Most superficial
and consists of cornified cells
– Squamous in shape, filled with keratin
Fig. 5.2
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Dermis
• Structural strength• Two layers
– Deeper layer - dense connective tissue; stretch marks (striae)
– Superficial layer underneath epidermis - loose connective tissue
Fig. 5.6
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Review Question
The layer of keratinocyte cells of the epidermis with the highest rate of cell division is the
(a) Stratum spinosum
(b) Stratum basale
(c) Stratum corneum
(d) Stratum granulosum
(e) Stratum lucidum
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Hypodermis• Skin rests on this,
but not a part• Also called
– Subcutaneous tissue– Superficial fascia
• Consists of loose connective tissue
• Types of cells– Fibroblasts– Adipose (fat) cells– Macrophages
• Subcutaneous fatFig. 5.6
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Accessory Skin Structures
• Hair– Found everywhere on human body except
palms, soles, lips, nipples, parts of external genitalia, and distal segments of fingers and toes
• Nails
• Glands– Sebaceous or oil glands– Sudoriferous or sweat glands
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Hair Structure• Composed of shaft and root
– Shaft protrudes above skin surface
– Root located below surface and base forms the hair bulb
– Hair follicle consists of layer of dermis and epidermis
• Arrector pili– Smooth muscle
– Raises hair
Fig. 5.9
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Nails
• Anatomy– Nail root
proximally
– Nail body distally: Eponychium or cuticle
• Growth– Grow continuously
unlike hair
Fig. 5.8
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Oil and Sweat Glands• Sebaceous glands
– Produce sebum
– Oils hair and skin surface
• Sudoriferous glands (sweat)– Most commonly found in
palms, soles and forehead
– Also found in axillae (arm pit), genitalia, around anus
– Ceruminous glands (cerumen or ear wax)
– Mammary glands
Fig. 5.10
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Points to RememberPoints to Remember
• Two components to integumentary system– Skin (epidermis & dermis)– Accessory structures (hair, nails and glands)
• Keratinization (accumulation of keratin) produces upper layer of cells of epidermis, hair and nails
• Two types of glands in skin– Sebaceous (oily)– Sudiferous (watery)
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Questions?