© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE INTEGUMENTARY SYSTEM Chapter 6

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction Skin –Large waterproof covering –UV light and chemical protection Accessory structures –Hair, nails, glands

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE LAYERS OF THE SKIN

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction Epidermis: upper layer –Epithelial tissue divided into sublayers Dermis: lower layer –Dense connective tissue –Connects skin to fat and muscle –Below dermis is subcutaneous layer called hypodermis

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Epidermis Stratified, squamous, keratinized, epithelium Keratinization –Cells move to surface, lose water and nuclei change Composed of five layers

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Epidermis (cont’d.) Stratum corneum –Outermost layer –Dead, keratinized cells –Barrier to light, heat, chemicals, microorganisms

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Epidermis (cont’d.) Stratum lucidum –One to two cell layers thick –Flat and transparent –Difficult to see

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Epidermis (cont’d.) Stratum granulosum –Two or three layers –Flattened cells –Active keratinization –Lose nuclei –Compact and brittle

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Epidermis (cont’d.) Stratum spinosum –Several layers of spiny-shaped cells –Desmosomes prevalent Desmosomes: interlocking cellular bridges

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Epidermis (cont’d.) Stratum germinativum –Rests on basement membrane –Lowermost layer called stratum basale –New cells produced here (mitosis) –Melanocytes: produce melanin Skin color Albinism

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Dermis Also called corium Structures found in dermis –Blood and lymph vessels –Nerves –Muscles –Glands –Hair follicles

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Dermis (cont’d.) Divisions –Papillary Adjacent to the epidermis –Reticular Between papillary and subcutaneous –Subcutaneous (hypodermis) Layers of fat below the dermis

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE ACCESSORY STRUCTURES OF THE SKIN

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Hair Covers most of the surface of the body Three parts: cuticle, cortex, medulla Shaft: visible portion Root: hair follicle Arrector pili: smooth muscle

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Hair (cont’d.) Growth –Hair follicle –Cycles of growth and rest Texture: straight, curly, or tightly curly Color: based on complex genetic factors

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Nails Modified epidermal cells –Lunula: white crescent Body: visible portion Root: covered by skin Growth occurs from the nailbed

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Nails (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Sebaceous Glands Produce sebum (oil) –Lubricates skin and hair Secretion controlled by endocrine system –Increases at puberty –Decreases in later life

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Sweat Glands Most numerous in palms and soles Not found on margins of the lips or head of the penis Each gland has secretory portion and excretory duct Sweating helps cool the body

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. FUNCTIONS OF THE INTEGUMENTARY SYSTEM

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Sensation Temperature receptors –Hot and cold Pressure receptors –Excessive pressure as pain –Mild pressure as pleasurable Combinations produce burning, itching, tickling

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Protection Prevents passage of harmful physical and chemical agents Melanin protects from UV rays Lipid content inhibits water loss Acid mantle: kills most bacteria Nails protect ends of our digits Hair acts as insulation and filter

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Thermoregulation Normal body temperature: 98.6 degrees F When external temperatures increase –Blood vessels dilate –Sweat occurs When external temperatures decrease –Blood vessels first dilate then constrict

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Secretion Sebum –Cosmetic gloss –Moisturizer –Antifungal/antibacterial properties Sweat –Essential in cooling process Vitamin D

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Animation – The Skin Watch the Skin animation and see the structures of the skin up close. Click Here to Play Skin Animation

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Animation – Tissue Repair Watch the Tissue Repair animation to understand how the skin heals and a scar is formed after a deep laceration. Click Here to Play Tissue Repair Animation

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary Discussed the layers of the epidermis and the process of keratinization Described the structure of the dermis Discussed the accessory structures of the skin including the hair and nails Discussed the different functions of the integumentary system