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Chapter 7. The Integumentary System. Integumentary system functions:. Protection Excretion Temperature maintenance Insulation and cushion Vitamin D3 synthesis Sensory detection. The integumentary system consists of. Cutaneous membrane Epidermis Dermis Accessory structures
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Chapter 7 The Integumentary System
Integumentary system functions: • Protection • Excretion • Temperature maintenance • Insulation and cushion • Vitamin D3 synthesis • Sensory detection
The integumentary system consists of • Cutaneous membrane • Epidermis • Dermis • Accessory structures • Subcutaneous layer • It is not part of the integumentary system • It separates the integumentary system from the deep fascia • Also known as hypodermis and superficial fascia
Cells of the epidermis • Keratinocytes • Most abundant • Produce keratin • Fibrous protein that makes the epidermis though and water resistant • Melanocytes • Secretes melanin • Protects the cell against UV rays • freckles
Cells of the epidermis • Langerhan’s cells • Cells that belong to the immune system • Merkel cells • Merkel discs = Merkel cell + nerve ending • Sense of touch
Layers of the epidermis: • Stratum germinativum or basale • Stratum spinosum • Stratum granulosum • Stratum lucidum • Stratum corneum
Stratum Germinativum (basale) • Single row of cells • Forms epidermal ridges • Basal or germinative cells • Merkel cells (touch) • Melanocytes
Stratum Spinosum • Prickle cells • Several layers of cells • Cells held together by desmosomes • Presence of Langerhan’s cells • Cells contain pre-keratin
Stratum Granulosum • 3 to 5 layers of keratinocytes • No cell divisions • Lamellated granules • Contain a water resistant glycolipid that reaches the extracellular space • Keratohyalin granules • Combine with the intermediate filaments to form keratin that will make the skin stronger
Stratum lucidum (clear layer) • Dead keratinocytes • Flat cells • In thick skin
Stratum corneum • Outmost layer • 20-30 layers of cells • Dead cells • Cytoplasm filled with keratin • Constantly shedding and replaced
Dermal layers • Papillary layer • Contains blood vessels, lymphatics • Free nerve endings • Meissner corpuscles (touch, pressure) • Loose areolar connective tissue • Presence of dermal papillae • Produce fingerprints • Genetically determined
Dermal layers • Reticular Layer • Dense irregular connective tissue • Fewer cells • Contains network of collagen and elastic fibers to resist tension • Sweat and sebaceous glands • Rich blood supply • Hair follicles • Pacinian corpuscles (deep pressure)
Dermis • Both layers are rich in collagen and elastic fibers • Numerous fibroblasts, adipocytes, macrophages • Richly vascularized • Regulation of body temperature • Decubitus ulcers
Skin color depends on • Blood supply • Carotene • Present in the s.corneum and hipodermis • Melanin
Abnormal skin color • Flushed • Fever, hypertension • Pale • Jaundice • Cyanoses
Nails • Nail bodycovers the nail bed • Nail production occurs at the nail matrix • Eponychium (cuticle) overlies root • Free edge of nail extends over hyponychium • Lunula • Root • Nail folds
Hairs • Originate in hair follicle • Composed of rootand shaft • Root base (hair papilla) surrounded by hair bulb and root hair plexus • Cuticle = superficial dead protective layer • Cortex • Medulla
Hair • Follicle • Epidermal layer • Internal epithelial root sheath • External epithelial root sheath • Glassy membrane • Connective root sheath • Papilla • Blood vessels enter the hair
Hair • Arrector pili muscle • Smooth muscle • When contracted cause dimpling of the skin
Cutaneous Glands • Sebaceous • Sudoriferous
Sebaceous glands • Discharge waxy sebum onto hair follicle or on the skin surface • Not present on palms and soles • Sebum • Oil + dead cells • Keep skin and hair moist • Black head • Acne
Sudoriferous glands • Apocrine sweat glands • Axilla and genital areas • Begin secretion at puberty • Produce odorous secretion rich in protein and fat • Merocrine(eccrine) sweat gland • All over the body • Regulates body temperature • Sweat or perspiration • Water, salt, urea
Fingerprint • Impressions caused by • Ink, sweat, oil, blood,etc • Patterns • Archs • Loops • whorls