Chapter 5 The Integumentary System Lecture Outline Integument Composition 1. Cutaneous membrane A. Epidermis B. Dermis 2. Accessory organs A. Hair B. Exocrine glands C. Nails Functions 1. Protection 2. Excretion 3. Temperature 4. Vitamin D3 5. Storage 6. Sensory Epidermis Characteristics 1. Stratified squamous epithelium 2. Avascular 3. Keratinocytes Types 1. Thick skin 2. Thin skin Layers 1. Stratum basale Epidermal ridges Fingerprints Hemidesmosomes Cells a. Basal / Germinative cells b. Melanocytes c. Tactile discs / Merkel cells 2. Stratum spinosum Keratinocytes Desmosomes Epidermal dendritic cells / Langerhans cells 3. Stratus granulosum Keratin fibers Keratohyaline granules Lamellated granules 4. Stratum lucidum Thick skin only 5. Stratum corneum Keratinization = cornification Soft keratin + keratohyline Glycolipids Insensible perspiration Callus Blister Skin color 1. Epidermal pigmentation A. Carotene Vitamin A B. Melanin Melanocytes Melanosomes UV protection Tyrosine Freckles Squamous cell carcinoma Melanoma 2. Dermal circulation Hemoglobin Vasodilation = red Vasoconstriction = pale Cyanosis Abnormalities Jaundice Addisons disease Adrenocorticotropic hormone Albinism Vitiligo Vitamin D3 production Cholesterol Vitamin D 3 Calcitriol Calcium absorption Dermis Contents: Connective tissue cells Accessory organs of epidermis Blood vessels Lymph vessels Nerves Pain & touch receptors Organization: 1. Papillary layer Areolar CT Dermal papillae 2. Reticular layer Dense irregular CT Lines of cleavage Contusion Sensory perception 1. Tactile discs / Merkel cells 2. Free nerve endings 3. Tactile corpuscles / Meissner’s corpuscles 4. Lamellated corpuscles / Pacinian corpuscles Subcutaneous layer / Hypodermis Areolar & adipose CT Sub Q injection Accessory structures 1. Hair Structure Hair follicle stratified squamous epithelium Internal root sheath Amy Warenda Czura, Ph.D.1SCCC BIO130 Chapter 5 HandoutExternal root sheath Glassy membrane Basal lamina Hair bulb Hair papilla CT & vessels Hair matrix melanocytes & epithelial stem cells Hair Hair root Hair shaft Cuticle Cortex hard keratin Medulla soft keratin Shape Flat = kinky Oval = wavy Round = straight Type 1. Vellus hairs no medulla 2. Terminal hairs Color: Melanin Iron Gray Growth: 1. Active phase 2. Regressive phase Club hair 3. Resting phase Alopecia Male pattern baldness Hair removal Function: UV protection Cushion Insulation Protection Sensory detection Hair root plexus Arrector pili muscle 2. Integumentary glands Exocrine A. Sebaceous glands Holocrine secretion Sebum (lipids, cholesterol, proteins, electrolytes) Functions -lubricate -prevent dehydration -inhibit bacteria Acne B. Sudoriferous / Sweat glands 1. Merocrine / Eccrine sudoriferous glands Merocrine secretion Sensible perspiration (water, electrolytes, nutrients, antibodies, antimicrobials, wastes) Functions -cooling -excretion -protection: prevent adherence wash Dermicidin 2. Apocrine sudoriferous glands Merocrine secretion (sensible perspiration + proteins, lipids) body odor Myoepithelial cells Special glands a. mammary glands milk b. ceruminous glands cerumen 3. Nails hard keratin Nail root Injury and repair Mesenchymal cells Germinative cells 1. Cut → bleed Mast cells → histamine → inflammation 2. Clot → scab Phagocytosis Statum basale division & migration Fibroblast & mesenchymal cell division Fibroblasts → collagen Endothelial cells → capillaries Granulation tissue 3. Epidermal migration 4. Scab shed Fibroblasts → collagen → scar Mesenchymal cells → CT cells Kelloid Burns First degree: epidermis Second degree: epidermis & superficial dermis Third degree: all cutaneous layers Skin grafts Aging ↓ stem cells & repair ↓ Epidermal dendritic cells & immune response ↓ Vitamin D3 and calcium absorption ↓ glandular activity ↓ circulation ↓ hair production ↓ elasticity ↓ sex characteristics Amy Warenda Czura, Ph.D.2SCCC BIO130 Chapter 5 HandoutStratified squamous epitheliumAvascularMostly keratinocytes: cells filled with soft keratin proteinTwo types: 1. Thick skin - up to 0.5mm, 5 layers, no hair, palmsand soles 2. Thin skin - 0.1mm or less, 4 layers, usually hairy,most of bodyStratum lucidumEpidermis = superficial integument / superficial cutaneous membraneLayers:Stratum basale - single layer, attached to basal lamina byhemidesmosomes, extends into dermis as epidermal ridges (dermis= dermal papillae), cells mostly basal/germinative cells (stem cells)that constantly divide, some melanocytes (melanin), some Tactilediscs /Merkel cells in hairless skin (touch receptors)Stratum spinosum - 8-10 layers keratinocytes attached bydesmosomes, some cells can divide, some Epidermal dendritic cells /Langerhans cells present (immune response)Stratum granulosum - 3-5 layers keratinocytes producing keratinfibers, keratohyaline granules, and lamellated granules, no celldivision, nuclei and organelles begin to disintegrateStratum lucidum - thick skin only, flat packed keratin filledkeratinocytesStratum corneum - 15-30 layers dead keratinocytes that have beenkeratinized (cornified): soft keratin fibers glued in parallel arrays bykeratohyaline, extracellular space filled with glycolipids fromlamellated granules (cornified = water and chemical resistant)Transit from stratum basale to stratum corneum: 15-30 daysDuration at stratum corneum: 7-14 daysComplete