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Sweat Glands • Oil Glands • Mammary Glands

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Sweat Glands • Oil Glands • Mammary Glands Chapter 4 The Integumentary System Lecture Presentation by Steven Bassett Southeast Community College © 2015 Pearson Education, Inc. Introduction • The integumentary system is composed of: • Skin • Hair • Nails • Sweat glands • Oil glands • Mammary glands © 2015 Pearson Education, Inc. Introduction • The skin is the most visible organ of the body • Clinicians can tell a lot about the overall health of the body by examining the skin • Skin helps protect from the environment • Skin helps to regulate body temperature © 2015 Pearson Education, Inc. Integumentary Structure and Function • Cutaneous Membrane • Epidermis • Dermis • Accessory Structures • Hair follicles • Exocrine glands • Nails © 2015 Pearson Education, Inc. Figure 4.1 Functional Organization of the Integumentary System Integumentary System FUNCTIONS • Physical protection from • Synthesis and storage • Coordination of immune • Sensory information • Excretion environmental hazards of lipid reserves response to pathogens • Synthesis of vitamin D3 • Thermoregulation and cancers in skin Cutaneous Membrane Accessory Structures Epidermis Dermis Hair Follicles Exocrine Glands Nails • Protects dermis from Papillary Layer Reticular Layer • Produce hairs that • Assist in • Protect and trauma, chemicals protect skull thermoregulation support tips • Nourishes and • Restricts spread of • Controls skin permeability, • Produce hairs that • Excrete wastes of fingers and supports pathogens prevents water loss provide delicate • Lubricate toes epidermis penetrating epidermis • Prevents entry of touch sensations epidermis • Stores lipid reserves pathogens on general body • Attaches skin to deeper • Synthesizes vitamin D surface 3 tissues • Sensory receptors detect touch, pressure, pain, and • Sensory receptors temperature detect touch, pressure, • Coordinates immune pain, vibration, and temperature response to pathogens and skin cancers • Blood vessels assist in thermoregulation © 2015 Pearson Education, Inc. Integumentary Structure and Function • Cutaneous Membrane • Epidermis • Superficial epithelium • Dermis • Underlying connective tissue • Deep to the dermis is the hypodermis • Also known as the subcutaneous layer or superficial fascia • This is not normally considered to be a part of the integument © 2015 Pearson Education, Inc. Figure 4.1 Functional Organization of the Integumentary System (1 of 2) Cutaneous Membrane Epidermis Dermis • Protects dermis from Papillary Layer Reticular Layer trauma, chemicals • Nourishes and • Restricts spread of • Controls skin permeability, supports pathogens prevents water loss epidermis penetrating epidermis • Prevents entry of • Stores lipid reserves pathogens • Attaches skin to deeper • Synthesizes vitamin D3 tissues • Sensory receptors detect • Sensory receptors touch, pressure, pain, and detect touch, pressure, temperature pain, vibration, and • Coordinates immune temperature response to pathogens • Blood vessels assist in and skin cancers thermoregulation © 2015 Pearson Education, Inc. Integumentary Structure and Function • Cutaneous Membrane • Accessory Structures • Hair follicles • Exocrine glands • sweat glands/sebaceous glands • Nails • Arrector pili muscles © 2015 Pearson Education, Inc. Figure 4.1 Functional Organization of the Integumentary System (2 of 2) Accessory Structures Hair Follicles Exocrine Glands Nails • Produce hairs that • Assist in • Protect and protect skull thermoregulation support tips • Produce hairs that • Excrete wastes of fingers and provide delicate • Lubricate toes touch sensations epidermis on general body surface © 2015 Pearson Education, Inc. Integumentary Structure and Function • Functions Include: • Physical protection • Regulation of body temperature • Excretion of products • Synthesis of products • Sensation • Immune defense © 2015 Pearson Education, Inc. Figure 4.2 Components of the Integumentary System (1 of 2) Capillary loop of subpapillary Cutaneous plexus Membrane Epidermis Papillary layer Dermis Reticular layer Subcutaneous layer (hypodermis) © 2015 Pearson Education, Inc. The Epidermis • Thick and Thin Skin • Thick skin • Found on palms and soles • Made of five layers of cells • Thin skin • Found on the rest of the body • Made of four layers of cells © 2015 Pearson Education, Inc. The Epidermis • There are four cell types found in the epidermis • Keratinocytes • Produce a tough protein called keratin • Melanocytes • Pigment cells located deep in the epidermis • Produce melanin (skin color) • Merkel cells • Sensory cells • Langerhans cells • Wandering macrophages © 2015 Pearson Education, Inc. The Epidermis • Layers of the Epidermis • Stratum basale (stratum germinativum) • Deepest layer • Stratum spinosum • Stratum granulosum • Stratum lucidum • Stratum corneum • Most superficial layer © 2015 Pearson Education, Inc. The Epidermis • Layers of the Epidermis • Stratum basale • Location of melanocytes • Cells in this area are undergoing active reproduction • Stratum spinosum • Keratinocytes are bound together by desmosomes © 2015 Pearson Education, Inc. The Epidermis • Layers of the Epidermis • Stratum granulosum • Keratinocytes produce lots of keratin • Stratum corneum • Superficial layer • Consists of interlocking, dehydrated, dead cells © 2015 Pearson Education, Inc. Figure 4.3 The Structure and Layers of the Epidermis Epidermis Characteristics (five layers) Stratum Surface • Multiple layers of flattened, dead, interlocking corneum keratinocytes • Typically relatively dry • Water resistant but not waterproof • Permits slow water loss by insensible perspiration Stratum • Appears as a glassy layer in thick lucidum skin only Stratum • Keratinocytes produce keratohyalin and keratin granulosum • Keratin fibers develop as cells become thinner and flatter • Gradually the cell membranes thicken, the organelles disintegrate, and the cells die Stratum • Keratinocytes are bound together by maculae spinosum adherens attached to tonofibrils of the cytoskeleton • Some keratinocytes divide in this layer • Langerhans cells and melanocytes are often present Stratum • Deepest, basal layer basale • Attachment to basal lamina • Contains epidermal stem cells, melanocytes, and Merkel cells Basal lamina Dermis Epidermis of thick skin LM × 225 © 2015 Pearson Education, Inc. The Epidermis • Epidermal Ridges • Stratum germinativum forms epidermal ridges • Ridges (dermal papillae) extend into the dermis • Creates ridges we call fingerprints © 2015 Pearson Education, Inc. Figure 4.7 The Structure of the Dermis and the Subcutaneous Layer Capillary loop of subpapillary plexus Dermal papillae Epidermal ridges Papillary layer Reticular layer Subpapillary plexus Cutaneous plexus Lymphatic vessel Adipocytes © 2015 Pearson Education, Inc. Figure 4.4 Thin and Thick Skin Epidermis Basal Stratum lamina corneum Epidermal ridge Stratum lucidum Dermal papilla Dermis Dermal Dermis papilla LM × 240 Epidermal LM × 240 ridge a The basic organization of the b Thin skin covers most of c Thick skin covers epidermis. The thickness of the exposed body surface. the surfaces of the the epidermis, especially the (During sectioning the palms and soles. thickness of the stratum statum corneum has corneum, changes radically pulled away from the depending on the location rest of the epidermis.) sampled. © 2015 Pearson Education, Inc. Figure 4.5 The Epidermal Ridges of Thick Skin Pores of sweat gland ducts Epidermal ridge SEM × 25 © 2015 Pearson Education, Inc. The Epidermis • Skin Color • Due to: • Dermal blood supply • Thickness of stratum corneum • Various concentrations of carotene and melanin • Under genetic control © 2015 Pearson Education, Inc. The Epidermis • Skin Color • Dermal blood supply • Reduction in blood flow results in a pale color • Sustained reduction in blood flow results in cyanosis © 2015 Pearson Education, Inc. The Epidermis • Epidermal Pigment Content • Carotene • Derived from carrots, corn, and squash • Can convert to vitamin A • Vitamin A is needed for synthesis of visual pigments in the photoreceptors of the eyes • Melanin • Produced and stored in melanocytes • Creates natural skin color and tan • Protects the skin against UV radiation © 2015 Pearson Education, Inc. Figure 4.6 Melanocytes Melanocytes in stratum basale Melanin pigment Basal lamina Thin skin LM × 600 a This micrograph indicates the location and orientation of melanocytes in the stratum basale of a dark-skinned person. Melanosome Keratinocyte Melanin pigment Melanocyte Basal lamina Dermis b Melanocytes produce and store melanin. © 2015 Pearson Education, Inc. The Epidermis • Melanocyte Activity • Exposure to UV light • Increases the rate of melanin formation • Tanning begins • Repeated exposure to UV light: • Can result in long-term epidermal and dermal damage • Results in abnormal connective tissue structure • Results in premature wrinkling • Can result in epidermal skin cancer © 2015 Pearson Education, Inc. The Epidermis • Vitamin D Formation • UV light converts a cholesterol-related precursor • Converts to vitamin D • Vitamin D1 undergoes changes in the liver and kidneys • Vitamin D1 converts to the active form of vitamin D (calcitriol) © 2015 Pearson Education, Inc. The Dermis • The dermis consists of two layers • Papillary layer • Superficial dermis • Reticular layer • Deep dermis © 2015 Pearson Education, Inc. Figure 4.7 The Structure of the Dermis and the Subcutaneous Layer Capillary loop of subpapillary plexus Dermal papillae Epidermal ridges Papillary layer Reticular layer Subpapillary plexus Cutaneous plexus Lymphatic vessel Adipocytes © 2015 Pearson
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