The Integumentary System 1 Integumentary system functions l

The Integumentary System 1

Integumentary system functions: l l l Protection Excretion Temperature maintenance Insulation and cushion Vitamin D 3 synthesis Sensory detection 2

The integumentary system consists of l Cutaneous membrane ¡Epidermis ¡Dermis l Accessory structures l 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 3

Integumentary System 4

The Epidermis 5

Cells of the epidermis l Keratinocytes ¡Most abundant ¡Produce keratin l. Fibrous protein that makes the epidermis though and water resistant l Melanocytes ¡Secretes melanin l. Protects the cell against UV rays ¡freckles 6

Cells of the epidermis l Langerhan’s cells ¡Cells that belong to the immune system l Merkel cells ¡Merkel discs = Merkel cell + nerve ending ¡Sense of touch 7

Layers of the epidermis: l Stratum germinativum or basale l Stratum spinosum l Stratum granulosum l Stratum lucidum l Stratum corneum 8

Layers of the Epidermis 9

Stratum Germinativum (basale) l Single row of cells l Forms epidermal ridges l Basal or germinative cells l Merkel cells (touch) l Melanocytes 10

Stratum Basale 11

Stratum Spinosum l Prickle cells l Several layers of cells l Cells held together by desmosomes l Presence of Langerhan’s cells l Cells contain pre-keratin 12

Stratum Granulosum l 3 to 5 layers of keratinocytes l No cell divisions l Lamellated granules ¡Contain a water resistant glycolipid that reaches the extracellular space l Keratohyalin granules ¡Combine with the intermediate filaments to form keratin that will make the skin stronger 13

Stratum lucidum (clear layer) l Dead keratinocytes l Flat cells l In thick skin 14

Stratum corneum l Outmost layer l 20 -30 layers of cells l Dead cells l Cytoplasm filled with keratin l Constantly shedding and replaced 15

The Dermis 16

Dermal layers l Papillary layer ¡Contains blood vessels, lymphatics ¡Free nerve endings ¡Meissner corpuscles (touch, pressure) ¡Loose areolar connective tissue ¡Presence of dermal papillae l. Produce fingerprints • Genetically determined 17

Dermal papilla 18

Fingerprints 19

Dermal layers l 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) 20

Dermis l Both layers are rich in collagen and elastic fibers l Numerous fibroblasts, adipocytes, macrophages l Richly vascularized ¡Regulation of body temperature ¡Decubitus ulcers 21

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Skin color depends on l Blood supply l Carotene ¡Present in the s. corneum and hipodermis l Melanin 23

Abnormal skin color l Flushed ¡Fever, hypertension l Pale l Jaundice l Cyanoses 24

Accessory Structures 25

Nails l Nail body covers the nail bed l Nail production occurs at the nail matrix l Eponychium (cuticle) overlies root l Free edge of nail extends over hyponychium l Lunula l Root l Nail folds 26

Nail 27

Hairs l Originate in hair follicle l Composed of root and shaft l Root base (hair papilla) surrounded by hair bulb and root hair plexus l Cuticle = superficial dead protective layer l Cortex l Medulla 28

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Hair l Follicle ¡Epidermal layer l. Internal epithelial root sheath l. External epithelial root sheath ¡Glassy membrane ¡Connective root sheath ¡Papilla l. Blood vessels enter the hair 30

Hair l Arrector pili muscle ¡Smooth muscle ¡When contracted cause dimpling of the skin 31

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Cutaneous Glands l Sebaceous l Sudoriferous 33

Sebaceous glands l Discharge waxy sebum onto hair follicle or on the skin surface l Not present on palms and soles l Sebum ¡Oil + dead cells ¡Keep skin and hair moist ¡Black head ¡Acne 34

Sebaceous Glands and Follicles 35

Sudoriferous glands l Apocrine sweat glands ¡Axilla and genital areas ¡Begin secretion at puberty ¡Produce odorous secretion rich in protein and fat l Merocrine (eccrine) sweat gland ¡All over the body ¡Regulates body temperature ¡Sweat or perspiration l. Water, salt, urea 36

Sweat Glands 37