Skin Physiology PDF

Cosmetology Description of skin By Anika Bristy 0 STARTUP X 1 Skin Integumentary system = body's outer layer. It consists of your skin,...

Cosmetology Description of skin By Anika Bristy 0 STARTUP X 1 Skin Integumentary system = body's outer layer. It consists of your skin, hair, nails and glands. STARTUP X 2 Skin Thickness of skin 0.5-3 mm STARTUP X 3 Function of Skin STARTUP X 4 Function of Skin STARTUP X 5 Skin Human body is protected from the surrounding by the skin. Entry of radiation, bacteria, fungi and water is controlled by the outer layer of the skin. Skin also absorbs oxygen (i.e. breathing), controls the loss of fluids, eliminates waste, secrets protective lubricants, grows hair, propagates sensitivity, regulates heat loss, cushions against mechanical shock, provides individual identification (moles, ridges, color, texture, odor etc.) and manufactures new skin cells. Though nearly all human skin is covered with hair follicles, it can appear hairless. STARTUP X 6  Description of Skin The skin is composed of three layers: Epidermis Dermis Subcutaneous or hypodermis STARTUP X 7  Epidermis layer ‘’Epi" coming from the Greek meaning "over" or "upon", is the outermost layer of the skin. Thickness range is from 0.05mm (eyelid) to 1.5mm on the palms and soles. Water resistant due to the keratinocytes Protective wrap over the body's surface which also serves as a barrier to infection. STARTUP X 8  Epidermis layer Epidermis contains no blood vessel. The cells get the nutrients by diffusion from the blood capillaries of dermis. The cells of this outermost layer are dead. Stratum granulosum begin to die because of their inability to get oxygen and nutrients via diffusion. Stratum Corneum cells flake off. Function of epidermis: ✓ Prevent penetration of irritant and allergen ✓ Prevent loss of water ✓ Maintain internal homeostasis ✓ Regulate pigmentation STARTUP X 9  Dust mite The Creature That Eats Your Skin! All they need to survive – warmth, moisture, skin flakes! 1-3 people out of 10, dust mites can trigger allergies and even asthma attacks. Control Dust & Humidity, Use cold & heat, Use allergenic cover, & DON’T THINK ABOUT IT! STARTUP X 10  Skin & Sun UVB (Calcidiol) 1,25 hydroxyvitamin D3 (Calcitriol) STARTUP X 11  Pigmentation system Melanin is produced by melanocytes by the action of an enzyme called tyrosinase. Formation of melanin is called melanogenesis. Melanin protects body from UV radiation. Melanin causes brown and black pigmentation which can be enhanced by exposure to sun, or by endocrine factors like in pregnancy. STARTUP X 12  HOW THE SUN CREATED RACE! The more eumelanin in epidermis = The darker skin Light skin= little eumelanin Freckles, carrot-red hair= Large amount of pheomelanin Geographical and genetic variations occur in melanin formation. STARTUP X 13  Dermis layer The dermis is tightly connected to the epidermis by a basement membrane. It is 25 times thicker than epidermis. Dermis is permeable. It provides nutrients to the epidermis, houses blood and nervous systems, contain hair follicles, sebaceous glands, apocrine glands, sweat glands. STARTUP X 14  Dermis layer Layers of dermis: Papillary Reticular Papillary layer: A layer of the dermis, directly underneath the epidermis. It’s much thinner than the reticular dermis. This layer contains (endings of) capillaries, collagen fibers, lymph vessels and sensory neurons. It has a loose network of connective tissue, this characteristic separates it from the reticular layer underneath. Reticular layer: The deep layer, forming a thick layer of dense connective tissue that houses blood vessels, nerve endings, hair follicles, and glands. A net-like structure of elastin fibers and collagen fibers surrounds the reticular dermis. STARTUP X 15  Dermis layer Strength and elasticity are two characteristics of the dermis. The dermis shapes and supports skin with tough connective tissue that uses strong, flexible fibers made of collagen and elastin. These fibers make the skin stretchable and resilient, also keep the skin toned and wrinkle-free at the young age. STARTUP X 16  Dermis layer: Scar STARTUP X 17  Dermis layer Nerves and Sense Organs: Skin is covered with nerve fiber, mostly in the face and extremities. Hair follicles also have nerve terminals. Skin can feel touch, warmth, cold, pressure and pain correctly. The purpose of these nerve fiber is to provide the central nervous system with information about the external environment and its effect on the skin. This information may stimulate responses, such as washing a painful cut finger, scratching an insect bite, or responding to a feeling of cold by putting on a sweater. STARTUP X 18  Dermis layer Blood Vessels: Epidermis contains no blood vessels, dermis has. They provide blood supply and nutrients to all skin cells. This is responsible for temperature control. When blood vessels are dilated, the skin appears flashed and heat loss is at a maximum. Histamine from the mast cells in the dermis, in case of allergy or skin damage, causes dilatation. STARTUP X 19  Dermis layer Sweat Glands: These are most numerous over the majority of the body surface with few exceptions like-eyelid, lips etc. In some areas they are as many as 600 per sq. cm. Sweat glands are concerned with both control of body temperature and excretion. Sweat is mostly water, with a pinch of salt and tiny amounts of other waste products. Evaporation of sweat has a cooling effect. Sweating is mainly controlled by nerves (Acetylcholine). Sweating also maintain internal body temperature. Another type of glands are Apocrine Glands are attached to the hair follicles of axillary, genital area. Their secretions are thought STARTUP X to contribute to individual odor. 20  Thermoregulation STARTUP X 21  Dermis layer Hair Follicles The human scalp contains approximately 120,000 follicles, which are epidermal invaginations consisting of keratinocytes and melanocytes that extend to the dermis. These follicles have a cycle of four different phases: anagen, catagen, telogen, and exogen. In a typical day, around 80 hairs are lost. STARTUP X 22  Dermis layer Sebaceous Glands: The ducts of sebaceous glands open into hair follicles or directly to the skin surface. Their secretion is sebum, a lipid substance commonly referred to as oil. The most significant concentrations are in the scalp, face, upper chest and shoulder—none in the palms and soles. Human sebum comprises glycerides and free fatty acids, cholesterol, wax esters, cholesterol esters, etc. Sebum inhibits the growth of bacteria on the skin’s surface. Another function of sebum is to prevent drying of skin and hair. STARTUP X 23  Subcutaneous layer The layer of skin beneath the dermis is sometimes called the subcutaneous fat, subcutis, or hypodermis layer. This layer provides insulation for the body. It also provides a cushion that works like a shock absorber surrounding your vital organs. The subcutaneous tissue is largely composed of fat cells. STARTUP X 24  Skin nutrition STARTUP X 25  Types of Skin STARTUP X 26  Epidermal Permeability Barrier The penetration rate of drugs through the skin appendages is faster than through the stratum corneum, but the skin appendages (sweat gland, sebaceous gland etc.) occupies only about 0.1% of the skin surface area, so it is generally considered that it is not the main way of drug absorption through the skin. Intercellular: The stratum corneum is not fully intact. The intercellular lipid material is made up of ceramides, cholesterol, cholesterol esters, and fatty acids. Natural essential oils and synthetic fragrances are small, oil based molecules and that makes them easy to absorb into skin. Intracellular: The second route of absorption is through the Stratum Corneum. Only very tiny molecules (≤ 500 Dalton) can absorb into skin this way. Solvents have an exceptional ability to disrupt the skin barrier. A study showed an average of 64% skin absorption rate was done using solvents like toluene, xylene, and methylene chloride. Duration of contact is also a factor in skin absorption of cosmetic ingredients, as is the condition of the skin. STARTUP X 27  Worksheet Draw the diagram and label it! STARTUP X 28  Worksheet: Match The following 1. Average adult skin weigh ____ % of body weight. A. Subcutaneous 2. Largest organ of human body. B. Melanin 3. Surface of healthy skin is slightly. C. D 4. Epidermis has __ layers. D. Skin 5. The outermost thinnest layer of skin. E. 25 6. Fibrous protein that is principal component of hair. F. Eumelanin 7. Muscle that causes goosebumps. G. Corneum 8. Outer most layer of the dermis. H. 5 9. Fatty tissue found below the dermis. I. Acidic 10. Oil glands connected to hair follicles. J. 10 11. Shedding of skin cells occurs at the stratum _____ layer. K. Papillary 12. Skin pigment. L. Sebaceous 13. Dermis layer is ___ times thicker than epidermis. M. Arrector pili 14. Vitamin enables body to absorb and use calcium. N. Keratin 15. Helps protect sensitive cells from UV rays. O. Epidermis STARTUP X 29  THANK YOU STARTUP X 30