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Chapter 4 The Integumentary system Figure 4.1 Functional Organization of the Integumentary System (1 of 2) Cutaneous Membrane Epidermis Dermis • Protects dermis from trauma, chemicals • Controls skin permeability, prevents water loss • Prevents entry of pathogens • Synthesizes vitamin D3 • Sensory receptors detect touch, pressure, pain, and temperature • Coordinates immune response to pathogens and skin cancers Papillary Layer Reticular Layer • Nourishes and supports epidermis • Restricts spread of pathogens penetrating epidermis • Stores lipid reserves • Attaches skin to deeper tissues • Sensory receptors detect touch, pressure, pain, vibration, and temperature • Blood vessels assist in thermoregulation © 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 protect skull • Produce hairs that provide delicate touch sensations on general body surface • Assist in thermoregulation • Protect and support tips of fingers and toes © 2015 Pearson Education, Inc. • Excrete wastes • Lubricate epidermis Layers of Skin Figure 4.3 The Structure and Layers of the Epidermis Epidermis (five layers) Surface Characteristics Stratum corneum • Multiple layers of flattened, dead, interlocking keratinocytes • Typically relatively dry • Water resistant but not waterproof • Permits slow water loss by insensible perspiration Stratum lucidum • Appears as a glassy layer in thick 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 Basal lamina Epidermis of thick skin © 2015 Pearson Education, Inc. LM × 225 Stratum spinosum • Keratinocytes are bound together by maculae adherens attached to tonofibrils of the cytoskeleton • Some keratinocytes divide in this layer • Langerhans cells and melanocytes are often present Stratum basale • Deepest, basal layer • Attachment to basal lamina • Contains epidermal stem cells, melanocytes, and Merkel cells Dermis Figure 4.2 Components of the Integumentary System (1 of 2) Cutaneous Membrane Epidermis Dermis Papillary layer Reticular layer Subcutaneous layer (hypodermis) © 2015 Pearson Education, Inc. Capillary loop of subpapillary plexus Dermal Papilla & Epidermal Ridge Epidermis Epidermal ridge Dermal papilla Dermis Figure 4.5 The Epidermal Ridges of Thick Skin Pores of sweat gland ducts Epidermal ridge SEM × 25 © 2015 Pearson Education, Inc. Stratum Basale & Melanocytes Melanocytes in stratum basale Melanin pigment Basal lamina Thin skin LM 600 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 Melanocytes produce and store melanin. Melanocytes & UV radiation Albino animals Stratum spinosum This slide used a special stain so you can see the Langerhan’s cells. Stratum granulosum - Thin skin vs thick skin Which of the following helps prevent skin damage by absorbing ultraviolet radiation? a. melanin b. carotene c. keratin d. a and c 4. Skin can regenerate effectively even after considerable damage because: a) Epidermis of skin has rich supply of small blood vessels b) Fibroblasts in dermis give rise to new epidermal germinal cells c) Contraction in the injured areas bring cells of adjacent strata together d) Stem cells persist in both epithelial & CT components of skin The color of the epidermis is due to a combination of all of the following EXCEPT the: a) variable quantities of carotene and melanin. b) dermal blood supply. c) thickness of the stratum corneum. d) amount of vitamin D. © 2015 Pearson Education, Inc. DERMIS Figure 4.7a The Structure of the Dermis and the Subcutaneous Layer Capillary loop of subpapillary plexus Dermal papillae Epidermal ridges Papillary layer of dermis Reticular layer Subpapillary plexus Lymphatic vessel Adipocytes © 2015 Pearson Education, Inc. Fi * Papillary layer Cutaneous plexus * SEM × 649 a The papillary layer of the dermis consists of loose connective tissue that contains numerous blood vessels (not visible), fibers (Fi), and macrophages (not visible). Open spaces, such as those marked by asterisks, would be filled with fluid ground substance. Figure 4.7b 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 Reticular layer of dermis SEM × 1340 b The reticular layer of the dermis contains dense, irregular connective tissue. © 2015 Pearson Education, Inc. Figure 4.7c 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 Subcutaneous layer c © 2015 Pearson Education, Inc. SEM × 268 The subcutaneous layer contains large numbers of adipocytes in a framework of loose connective tissue fibers. Which of the following allows the skin to stretch and recoil? a) keratin b) collagen c) melanin d) vitamin D © 2015 Pearson Education, Inc. Which of the following would be considered the cutaneous layer? a) dermis and hypodermis b) epidermis and dermis c) epidermis, dermis, and hypodermis d) epidermis only © 2015 Pearson Education, Inc. Figure 4.9a Accessory Structures of the Skin Exposed shaft of hair Hair shaft Boundary between hair shaft and hair root Hair root Sebaceous gland Arrector pili muscle Connective tissue sheath Hair bulb Hair papilla a A diagrammatic view of a single hair follicle. © 2015 Pearson Education, Inc. Figure 4.9b Accessory Structures of the Skin Hair follicle, cross section Arrector pili muscle Epidermis Sebaceous gland Dermis Hair Subcutaneous adipose tissue Cortex Hair bulb Medulla Hair papilla Scalp, sectional view LM × 66 b A light micrograph showing the sectional appearance of the skin of the scalp. Note the abundance of hair follicles and the way they extend into the dermis and hypodermis. © 2015 Pearson Education, Inc. Figure 4.10a Hair Follicles Hair Hair Structure The cortex contains thick layers The cuticle, although of the hair contains a of hard keratin, which give the thin, is very tough, and flexible soft keratin. hair its stiffness. it contains hard keratin. The medulla, or core, Sebaceous gland Arrector pili muscle Connective tissue sheath Root hair plexus a A longitudinal section and a cross section through a hair follicle © 2015 Pearson Education, Inc. Hair follicle structures Figure 4.15a Structure of a Nail Direction of growth Free edge Lateral nail fold Nail Lunula Eponychium Proximal nail fold a View from the surface © 2015 Pearson Education, Inc. Figure 4.12 A Classification of Exocrine Glands in the Skin Exocrine Glands consist of • Assist in thermoregulation • Excrete wastes • Lubricate epidermis Sweat Glands Sebaceous Glands • Secrete oily lipid (sebum) that coats hair shaft and epidermis • Provide lubrication and antibacterial action Sebaceous Glands Sebaceous Follicles Secrete into hair follicles Secrete onto skin surface • Produce watery solution by merocrine secretion • Flush epidermal surface • Perform other special functions Apocrine Sweat Glands • Limited distribution (axillae, groin, nipples) • Produce a viscous secretion of complex composition • Possible function in communication • Strongly influenced by hormones • Merocrine secretion mechanism • Widespread • Produce thin secretions, mostly water • Controlled primarily by nervous system • Important in thermoregulation and excretion • Some antibacterial action special apocrine glands Ceruminous Glands Mammary Glands Secrete waxy cerumen into external ear canal © 2015 Pearson Education, Inc. Merocrine Sweat Glands Apocrine glands specialized for milk production Figure 4.13 Sebaceous Glands and Follicles (2 of 2) Lumen (hair removed) Wall of hair follicle Basal lamina Discharge of sebum Lumen Breakdown of cell membranes Mitosis and growth Sebaceous gland © 2015 Pearson Education, Inc. Germinative cells LM × 150 Figure 4.14a Sweat Glands Myoepithelial cell Connective tissue of dermis Sweat pore Duct Apocrine gland cells Lumen LM × 440 a Apocrine sweat glands are found in the axillae (armpits), groin, and nipples. They produce a thick, potentially odorous fluid. © 2015 Pearson Education, Inc. Duct of apocrine sweat gland Sectional plane through apocrine sweat gland Cross section of merocrine sweat gland Which of the following glands produces the type of sweat that is involved in cooling the body during and after a vigorous game of basketball? a) ceruminous glands b) sebaceous glands c) merocrine sweat glands d) apocrine sweat glands © 2015 Pearson Education, Inc. Which type of integumentary gland is involved in acne formation? a) apocrine glands b) merocrine glands c) sebaceous glands d) ceruminous glands © 2015 Pearson Education, Inc. Figure 4.16 The Skin during the Aging Process Fewer Active Melanocytes • Pale skin • Reduced tolerance for sun exposure Fewer Active Follicles Thinner, sparse hairs Reduced Skin Repair Skin repairs proceed more slowly. Decreased Immunity The number of dendritic cells decreases to about 50 percent of levels seen at maturity (roughly age 21). Thin Epidermis • Slow repairs • Decreased vitamin D production • Reduced number of Langerhans cells Reduced Sweat Gland Activity Tendency to overheat © 2015 Pearson Education, Inc. Changes in Distribution of Fat and Hair Dry Epidermis Due to reductions in sex hormone levels Reduction in sebaceous and sweat gland activity Reduced Blood Supply Thin Dermis • Slow healing • Reduced ability to lose heat Sagging and wrinkling due to fiber loss Watch “Skin” segment National Geographic youtube 5min 40sec Which of the following is a primary function of the integument? a. thermoregulation b. absorption c. storage of calcium reserves d. locomotion Thick skin and thin skin refer to differences in: a) Papillary layer c) Dermis b) Hypodermis d) Epidermis Layer of skin that contains bundles of collagen fibers & elastin for strength: a) Papillary layer c) Reticular layer b) St. corneum d) St. basale Fingerprint ridge patterns on the fingertips are unique to each person and are determined by: a. genetics. b. epidermal ridges. c. dermal papillae. d. all of the above 3. Epidermal ridges: a) Are at the surface of epidermis only b) Cause ridge patterns on surface of skin c) Connect statum spinosum with stratum lucidum d) Are determined by environmental factors The subcutaneous layer: a. helps reduce heat loss in infants and small children. b. is an integral part of the integument. c. is evenly distributed throughout the body, and between sexes. d. consists of dense regular connective tissue.