Functions Of The Integumentary System

Chapter 5

Integumentary System

5-1

Functions of the
Integumentary System
• Structures that are part of the integument
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Skin
Hair
Nails
Glands

• Overview of Functions
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Protection
Sensation
Temperature regulation
Vitamin D production
Excretion
Immunity
5-2

Skin
• Epidermis: Superficial layer of epithelial tissue.
• Dermis: Deep layer of connective tissue.
– Structural strength

• Subcutaneous tissue
– Not part of skin
– Loose connective tissue that connects skin to underlying structures

5-3

Epidermis
• Avascular; nourished by diffusion from capillaries of the papillary layer of the dermis
• Composed of cells arranged into layers or strata.
• Separated from dermis by basement membrane

5-4

Epidermal Cells
• Cell types
– Keratinocytes: most cells. Produce keratin for strength
– Melanocytes: contribute to skin color. Melanin produced by these cells then transferred to keratinocytes. Same number of melanocytes in all people.
– Langerhans’ cells: part of the immune system
– Merkel’s cells: detect light, touch, and superficial pressure
• Keratinization: as cells move outward through the layers they fill with keratin, die, and serve as a layer that resists abrasion and forms permeability layer

5-5

Epidermal Strata
Stratum basale (germinitivum)
– Deepest portion of epidermis and single layer.
Stratum spinosum Limited cell division.

Stratum granulosum In superficial layers nucleus and other organelles degenerate and cell dies

Stratum lucidum
– Thin, clear zone. Found only in palms and soles

Stratum corneum
– Most superficial and consists of dead cells

5-6

Epidermal Layers and Keratinization

5-7

5-8

Thick and Thin Skin
• Thick skin
– Has all 5 epithelial strata
– Found in areas subject to pressure or friction
• Palms of hands, fingertips, soles of feet

– Fingerprints and footprints. Papillae of underlying dermis in parallel rows

• Thin skin
– More flexible than thick skin
– Covers rest of body
– Hair grows here
• Callus. Increase in number of layers in stratum corneum.
When this occurs over a bony prominence, a corn forms.
5-9

Skin Color
• Pigments
– Melanin: provides for protection against UV light.
Melanocytes. processes extend between keratinocytes.
• Albinism: deficiency or absence of pigment. Production determined by genetics, hormones, exposure to light

– Carotene: yellow pigment. From vegetables.
Accumulates in stratum corneum, in adipose cells of dermis, and in Subcutaneous tissue.

5-10

Dermis
• Gives structural strength. C.T. with many fibers, fibroblasts, macrophages. Some adipocytes and blood vessels.
• Contains nerves, blood vessels, hair follicles, smooth muscles, glands, and lymphatic vessels.
• Sensory functions: pain, itch, tickle, temperature, touch, pressure, two-point discrimination.

5-11

Two Layers of the Dermis
• Two layers variable in thickness
– Papillary. Superficial (outer) 1/5. Areolar with lots of elastic fibers. Dermal papillae, capillary beds.
– Reticular: Deep (inner) 4/5. Dense irregular C.T. Collagen and elastic fibers. In the figure see: some adipose, hair follicles, nerves, oil glands, ducts of sweat glands, heat sensors. 5-12

N

Dermis: Disorders
• Striae
• Blister

13

Subcutaneous tissue
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Deep to skin
Consists of loose connective tissue with collagen and elastic fibers
Types of cells
– Fibroblasts
– Adipose cells
– Macrophages
Also called
– Hypodermis
– Superficial fascia
Contains about one-half of body’s adipose tissue. Functions as
– Energy source
– Insulation
– Padding
5-14

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

5-15

Hair Structure

5-16

Hair Structure
• Hair Growth
– Regular hair loss means hair is being replaced.
– Permanent hair loss: pattern baldness most common cause • Hair Color. Caused by varying amounts and types of melanin. Melanin can be black-brown and red
• Muscles. Arrector

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