SKIN & APPENDAGES

1. SKIN & APPENDAGES PROF. DR. FAUZIAH OTHMAN DEPT OF HUMAN ANATOMY

2. Contents: • Function of skin • Epidermis- layer & cell of epidermis • Dermis –papillary layer & reticular layer • Subcutaneous tissue • Blood vessels & skin sensorial receptors • Hairs • Nails • Glands of skin: sweat gland & sebaceous gland.

3. Skin layers: epidermis, dermis, and subcutis, showing a hair follicle, sweat gland & sebaceous gland.

4. Function of Skin • Protection • Sensation • Heat regulation • Control of evaporation • Aesthetics and communication • Storage and synthesis • Excretion • Absorption • Water resistance

5. Epidermis- layer & cell of epidermis • Outermost layer of the skin • About 90% of the epidermal cells are keratinocytes • Made up of stratified squamous epithelium with an underlying basallamina.

6. 5 layers • stratum basale • stratum spinosum • stratum granulosum • stratum lucidum • stratum corneum Bottom Top

8. Cell of epidermis • Three types of specialized cells • Melanocyte= produces pigment (melanin) • Langerhans' cell = frontline defense of the immune system in the skin • Merkel's cell's = is not clearly known

10. Dermis –papillary layer & reticular layer • Layer of skin beneath the epidermis. • Consists -connective tissue - cushions the body from stress and strain. • Tightly connected to the epidermis - basement membrane, and harbors many nerve endings that provide the sense of touch and heat.

11. It contains the hair follicles, sweat glands, sebaceous glands, apocrine glands, and blood vessels. The blood vessels in the dermis provide nourishment and waste removal to its own cells, as well as the Stratum basale of the epidermis.

12. superficial area adjacent= papillary region • The dermis Deep thicker area= Reticular region

13. Papillary Layer • Thin arrangement of collagen fibers -fingerlike projections -composed of loose areolar connective tissue • Fx= supplies nutrients =regulates temperature (Constriction and expansion control the amount of blood that flows through the skin and dictate whether body heat is dispelled when the skin is hot or conserved when it is cold.)

14. Reticular Layer • Thicker and made of thick collagen fibers that are arranged in parallel to the surface of the skin. • Denser than the papillary dermis, and it strengthens the skin, providing structure and elasticity. • It also supports other components of the skin, such as hair follicles, sweat glands, and sebaceous glands.

15. Subcutaneous Tissue • Layer of tissue directly underlying the cutis. • composed of adipose tissue & connective tissue that houses larger blood vessels and nerves. • The thickness depends on the amount of fat present.Its physiological function includes insulation and storage of nutrients

16. Blood vessels & skin sensorial receptors

17. Heat, cold, touch, texture, pressure, vibration, and tissue injury (pain) • abundant on the face, palms, fingers, soles, nipples and genitals. • relatively few on the back, and joint areas

18. sensory receptors in skin

20. Hairs • Itself is dead, but it's produced by living cells. • largely made up of a protein called keratin. • Cells in the hair follicle regularly produce the keratin and other proteins that become incorporated into the hair shaft. • Coloration comes from melanocytes which produce the brown pigment melanin

23. Nails • made of a tough protein called keratin and have many different parts

24. Nail body- visible portion of the nail • Nail bed –cover an area epidermis • The free edge of the nail-distal portion that continues past the nail bed • Hyponychium – an area of thickened stratum corneum.

25. Nail root - nail production occurs • Eponychium/ cuticle - aportion of stratum corneum of the nail root extend over the exposed. • Lunula- near the root, vessels may be obscured, leaving pale cresent.

26. Glands of skin: sweat gland & sebaceous gland

28. Skin contains 2 types of exocrine glands 1. Sebaceous glands ( produce oily lipid that coat hair shafts & the epidermis) 2. Sweat glands ( produce watery solution & perform other special functions.)

29. Sebaceous glands • Holocrine glands that discharge a waxy, oily secretion into hair follicles • Communicate with the single follicle share a duct & thus classified as simple branched alveolar glands

30. Gland cell = produce large quantities of lipid- mature • Secretion of lipids= sebum ( triacylglycerides+ cholesterol+ proteins + electrolyte)

31. Sweat gland • Other name=Sudoriferous glands • Apocrine gland • Merocrine gland * Names refer to the mechanism of the secretion

32. The terms thick and thin refer to the thickness of the epidermis. Most of the body is covered by thin skin, which is 0.003 inches (0.08 millimeters) thick. This skin contains hair follicles, sebaceous glands, and arrector pili muscles.

33. The epidermis in thick skin may be six times thicker than the epidermis that covers the general body surface. Thick skin does not have hair, smooth muscles, or sebaceous glands. Thick skin on the palms of the hands, the fingertips, and soles of the feet may be covered by many layers of keratinized cells that have cornified.