The Integumentary System 1

Protection Excretion Temperature maintenance Insulation and cushion Vitamin D3 synthesis Sensory detection Integumentary system functions: 2

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 The integumentary system consists of 3

Integumentary System 4

The Epidermis 5

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 6

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 7

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

Layers of the Epidermis 9

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

Stratum Basale 11

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

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 13

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

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

The Dermis 16

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 17

Dermal papilla 18

Fingerprints 19

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) 20

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

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

Flushed  Fever, hypertension Pale Jaundice Cyanoses Abnormal skin color 24

Accessory Structures 25

Nail body covers 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 Nails 26

Nail 27

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

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

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

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Sebaceous Sudoriferous Cutaneous Glands 33

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 Sebaceous glands 34

Sebaceous Glands and Follicles 35

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 Sudoriferous glands 36

Sweat Glands 37