BSC2085 01 Fall 2015 Lesson 7 Chapter 5 The Integumentary System An Introduction to Tissues Learning Outcomes 5 1 Describe the main structural features of the epidermis and explain the functional significance of each 5 2 Explain what accounts for individual differences in skin color and discuss the response of melanocytes to sunlight exposure 5 3 Describe the interaction between sunlight and vitamin D3 production 2015 Pearson Education Inc An Introduction to Tissues Learning Outcomes 5 5 Describe the structure and functions of the dermis hypodermis 5 6 Describe the structure and functions of the 5 7 Describe the mechanisms that produce hair and explain the structural basis for hair texture and color 2015 Pearson Education Inc An Introduction to Tissues Learning Outcomes 5 8 the glands 5 9 nails 5 10 and 5 11 skin 2015 Pearson Education Inc Discuss the various kinds of glands in skin and list the secretions of those Describe the anatomical structure of and explain how they are formed Explain how the skin responds to injury repairs itself Summarize the effects of aging on the An Introduction to the Integumentary System The Integument Is the largest system of the body 16 of body weight 1 5 to 2 m2 in area The integument is made up of two parts 1 2 Cutaneous membrane skin Accessory structures 2015 Pearson Education Inc An Introduction to the Integumentary System Cutaneous Membrane consist of two components 1 Outer epidermis 2 Superficial epithelium epithelial tissues Inner dermis Connective tissues 2015 Pearson Education Inc An Introduction to the Integumentary System Accessory Structures Originate in the dermis Extend through the epidermis to skin surface Includes Hair Nails Multicellular exocrine glands 2015 Pearson Education Inc An Introduction to the Integumentary System The integumentary system is connected to Cardiovascular system By blood vessels in the dermis Nervous system By sensory receptors that detect stimuli for pain touch and temperature 2015 Pearson Education Inc An Introduction to the Integumentary System Hypodermis Superficial Fascia or Subcutaneous Layer not considered part of the integumentary system Located below the dermis Composed of loose connective tissue Location of hypodermic injections 2015 Pearson Education Inc Figure 5 1 The Components of the Integumentary System Cutaneous Membrane Epidermis Papillary layer Reticular layer Dermis Hypodermis Accessory Structures Hair shaft Pore of sweat gland duct Tactile Meissner s corpuscle Sebaceous gland Arrector pili muscle Sweat gland duct Hair follicle Lamellated pacinian corpuscle Nerve fibers Sweat gland Artery Vein Cutaneous plexus Fat An Introduction to the Integumentary System Five main functions of skin 1 Protection of underlying tissues and organs 2 Excretion of salts water and organic wastes 3 Maintenance of body temperature insulation 4 Production of melanin keratin vitamin D3 and 5 Detection of touch pressure pain and glands and evaporation storage of lipids temperature 2015 Pearson Education Inc Figure 5 2 The Cutaneous Membrane and Accessory Structures Integumentary System FUNCTIONS Physical protection from environmental hazards Storage of lipids Coordination of immune response to pathogens and cancers in skin Sensory information Synthesis of vitamin D3 Excretion Thermoregulation Cutaneous Membrane Accessory Structures Epidermis Dermis Hair Follicles Exocrine Glands Nails Protects the dermis prevents water loss and the entry of pathogens and synthesizes vitamin D3 Sensory receptors detect touch pressure pain and temperature Papillary Layer Nourishes and supports epidermis Reticular Layer Has sensory receptors that detect touch pressure pain vibration and temperature Blood vessels assist in thermoregulation Hairs protect skull and provide delicate touch sensations on general body surface Assist in temperature regulation and waste excretion Protect and support tips of fingers and toes 5 1 Epidermis The Epidermis Is avascular stratified squamous epithelium Nutrients and oxygen diffuse from capillaries in the dermis Dominated by keratinocytes most abundant type of epithelial cells 2015 Pearson Education Inc Figure 5 3 The Epidermis Figure 5 3 The Epidermis 2015 Pearson Education Inc 5 1 Epidermis Thin Skin Thick Skin feet Covers most of the body Has four layers of keratinocytes Covers the palms of the hands and soles of the Has five layers of keratinocytes 2015 Pearson Education Inc Figure 5 3 The Epidermis 2015 Pearson Education Inc 5 1 Epidermis Structures of the Epidermis The five strata of keratinocytes in thick skin From basal lamina to free surface from inferior layer to superior layer 1 2 3 4 5 Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum missing in thin skin Stratum corneum 2015 Pearson Education Inc Figure 5 3 The Epidermis Part 2 of 3 Stratum corneum Stratum lucidum Dermal papilla Epidermal ridge Surface Epidermis Stratum corneum Characteristics Multiple layers of flattened dead interlocking keratinocytes Water resistant but not waterproof Permits slow water loss by insensible perspiration Appears as a glassy layer in thick skin only Keratinocytes produce keratohyalin and keratin Keratin fibers develop as cells become thinner and flatter Gradually the plasma membranes thicken the organelles disintegrate and the cells die Keratinocytes are bound together by desmosomes Deepest basal layer Attachment to basement membrane Contains basal cells stem cells melanocytes and tactile cells Merkel cells Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Thick skin LM 200 Basement membrane Dermis 5 1 Epidermis 1 Stratum Basale Is attached to basement membrane by hemidesmosomes Forms a strong bond between epidermis and dermis Forms epidermal ridges basis of fingerprints Dermal papillae tiny mounds Increase the area of basement membrane Strengthen attachment between epidermis and dermis Has many basal cells or germinative cells 2015 Pearson Education Inc Figure 5 3 The Epidermis Part 3 of 3 Pores of sweat gland ducts Epidermal ridge Thick skin SEM 20 Ridge patterns on skin increases surface area and friction ensuring a secure grip 5 1 Epidermis Specialized Cells of Stratum Basale 1 2 Merkel cells Found in hairless skin Respond to touch trigger nervous system Melanocytes Contain the pigment melanin Scattered throughout stratum basale 2015 Pearson Education Inc 5 1 Epidermis 2 Stratum Spinosum the spiny layer Produced by division of stratum basale Eight to ten layers of
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