STRUCTURES OF THE SKIN

1. STRUCTURES OF THE SKIN HCT I

2. Layers of The Skin • Two primary layers • Epidemis • Dermis • Subcutaneous Tissue- A layer of loose connective tissue and fat that supports the epidermis and dermis. • Insulates the body • Stored source of energy • Shock absorbing pad

3. Epidermis • The outermost and thinnest primary layer of skin. Cells are arranged in distinct layers • Thickness varies on the body. • Thinnest on the eyelids • Thickest on the palms and soles of the feet. • Stratum Germinativum- innermost layer where cells divide and push already formed cells to the surface. • WHY IS CELL REGENERATION IMPORTANT? • Maintaining the skin barrier helps to defend against infection even with injuries.

4. Epidermis • Keratin- a tough waterproof protein that replaces a cells cytoplasm as they approach the surface • Provides the outmost layer of skin with abrasion-resistance and protective qualities. • Stratum Corneum- Outmost layer of keratin filled cells, made up of dead flat skin cells that shed every couple of weeks. • DO YOU KNOW WHAT MOST DUST IS MADE OF?

5. EPIDERMIS • PIGMENT CONTAINING LAYER- epidermal layer that contains pigments called: • MELANOCYTES ,(a specialized epidermal cell) which produces a brown pigment called melanin • Amount of melanin depends on genetics • Increased melanin= increased skin color • Sunlight can increase the amount of melanin produced.

6. EPIDERMIS • Dermal Epidermal Junction-the area between the epidermis and dermis. • Break down of this junction can lead to blisters. • Burns • Friction • Exposure to irritants (poison ivy)

7. Dermis • Deeper and thicker layer of primary skin layers • Composed largely of connective tissue • Dermal papillae-(upper layer) • Important part of the dermal epidermal junction helping to keep the skin layers together • Form groves and ridges unique to each individual. • Do you know what the ridges and groves are called? • FINGERPRINTS

8. Dermis • Deeper areas contain a network of collagen and elastic fibers • These elastic fibers decrease with age contributing to wrinkles • Dermis also contains • Nerve endings • Sweat and sebaceous glands • Blood vessels • Muscle fibers • Hair follicles

9. Appendages of the skin • HAIR • Born with hair all over our bodies. Newborn hair is called lanugo • Hair follicle- an epidermal tube-like structure required for hair growth • Shaft- visible part of the hair • Root= lies hidden in the follicle • Hair papilla- where hair growth begins • Hair bulb- at the base of the follicle (hair papilla is located here) • Arrectorpili- specialized muscle that produces goose pimples

10. Receptors • Specialized nerve endings – makes it possible for skin to act as a sense organ • Meissner’s corpuscle- detects light tough • Pacinian corpuscle- capable of detecting pressure

11. SKIN GLANDS • TWO TYPES • Sweat (sudoriferous) • Sebaceous • Sweat or Sudoriferous Glands • Eccrine sweat glands-most numerous, important and wide spread. • Produce perspiration, which flows out through pores on the surface of the skin • Assist with body temperature regulation

12. Sweat or sudoriferous glands • Apocrine sweat glands • Found primarily in the axilla and genitalia • Secrete a thicker milky secretion • Breakdown of secretion by skin bacteria produces odor • WHEN DO APOCRINE SWEAT GLANDS ENLARGE AND START FUNCTION? PUBERTY

13. Sebaceous glands • Secrete oil or sebum for hair and skin • Level of secretion increases during adolescence • Amount of secretion regulated by sex hormones • Sebum in sebaceous gland ducts may darken to form a blackhead • Acne vulgaris-inflammation of sebaceous gland ducts

15. Structure of the skin