PHSC 1205 Unit 2.1 Integumentary System PDF

Unit 2.1 Parts and Functions of the Integumentary System Micah M.Areja Lorraine V. Tagle Stan Matthew S. Taylaran UNIT II Integumentary System A. Skin and the accessory structures B. Major functions C. Characteristics and functions of the different skin components D. Structu...

Unit 2.1 Parts and Functions of the Integumentary System Micah M.Areja Lorraine V. Tagle Stan Matthew S. Taylaran UNIT II Integumentary System A. Skin and the accessory structures B. Major functions C. Characteristics and functions of the different skin components D. Structural features of the epidermis E. Body’s response to injury Intended Learning Outcomes 1. Review of the basic anatomy of the integumentary system 2. Describing the functions of the components of Integumentary system 3. Explaining the mechanism of scar formation 4. Explaining the pathophysiology of Burn Injuries and Psoriasis 5. Discussing the physiological aspects of skin infections and allergies 6. Identifying common drugs for representative skin disorders Introduction ❏ Integumentary system include the skin and its accessory structures including hair, nails and glands, as well as blood vessels, muscles and nerves ❏ Dermatology is the medical specialty for the diagnosis and treatment of disorders of the integumentary system Skin Structure ❏ The skin (cutaneous membrane) covers the body and is the largest organ of the body by surface area and weight ❏ Its area is about 2 square meters (22 square feet) and weighs 4.5-5kg (10-11lb), about 16% of body weight ❏ It is 0.5-4mm thick, thinnest on the eyelids, thickest on the heels; the average thickness is 1-2mm A newborn has a skin surface area three times greater by volume than does an adult.  Skin Structure Consists of two major layers: ❏ epidermis ❏ outer, thinner layer (epithelial tissue) ❏ dermis ❏ inner, thicker layer Subcutaneous layer aka hypodermis ❏ which attaches the skin to the underlying tissues and organs Composition and Structure ❏ The epidermis is composed of keratinized stratified squamous epithelium Epidermis Four major types of cells: ❏ Keratinocytes (90% of the cells) produce keratin which is a tough fibrous protein that provides protection ❏ Melanocytes: which produce the pigment melanin that protects against damage by ultraviolet radiation ❏ Langerhans cells: involved in immune responses, arise from red bone marrow ❏ Merkel cells: which function in the sensation of touch along with the adjacent tactile discs ; least numerous  Layers of the Epidermis ❏ Stratum basale (deepest layer) or stratum germinativum, where continuous cell division occurs which produces all the other layers ❏ Stratum spinosum, 8-10 layers of keratinocytes ❏ Stratum granulosum, which includes keratohyalin and lamellar granules ❏ Stratum corneum: composed of many sublayers of flat, dead keratinocytes called corneocytes or squames that are continuously shed and replaced by cells from deeper strata; constant friction can stimulate formation of a callus.  Thin and Thick Skin Where friction is Most regions of the greatest (fingertips, body: palms, and soles): have four major have five major layers (thin skin) layers (thick skin) stratum basale, stratum basale, stratum spinosum, stratum spinosum, stratum granulosum, stratum granulosum, stratum lucidum, and a thin stratum corneum and a thick stratum corneum.  Epidermis ❏ Stratum lucidum is present only in thick skin (the skin of the fingertips, palms, and soles) ❏ Keratinization, the accumulation of more and more protective keratin, occurs as cells move from the deepest layer to the surface layer ❏ Dandruff - an excess of keratinized cells shed from the scalp Dermis is composed of connective tissue containing collagen and elastic fibers Structural Basis of Skin Color Variations in skin color arise from variations in the amounts of three pigments: melanin, carotene(yellow) and hemoglobin (red) ❏ Melanin - a yellow-red or brown-black pigment produced by melanocytes (located mostly in the epidermis, where it absorbs UV radiation). The amount of melanin causes the skin’s color to vary from pale yellow to red to tan to black The number of melanocytes are about the same in all people; differences in skin color is due to the amount of pigment produced Structural Basis of Skin Color ❏ Carotene - yellow-orange pigment (found in the stratum corneum, dermis, and subcutaneous layer) ❏ Hemoglobin - red color (located in erythrocytes flowing through dermal capillaries) Sun Protection Jim, a technician working in your pharmacy, asks you to recommend a sunscreen for him to take to the beach for spring break. He has fair skin and states that he usually gets some minimal redness on his skin after only 10 minutes in the sun. If you recommend a sun protection factor (SPF) product of 15 and assume Jim applies this product correctly, for how long will Jim be able to stay in the sun before he gets the same minimal degree of redness on his skin as noted above? A. 30minutes B. 2.5 hours C. 6 hours D. 45minutes E. 1.5 hours The SPF is the minimal erythema dose (MED) of sunscreen-protected skin divided by the MED of unprotected skin. An SPF of 15 means that, if the sunscreen is applied properly, the user can stay out in the sun about 15 times longer to get a minimal redness reaction compared to being in the sun with unprotected skin (i.e., with no sunscreen application).  Sun Protection Factor A sunscreen's effectiveness is typically measured by its sun protection factor (SPF), which is calculated as the UV energy needed to create a minimal erythemal dose (MED) on skin that is protected divided by the UV energy needed to produce a MED on skin that is not protected. SPF 15 sunscreen would enable one to stay in the sun without burning for roughly 150 minutes if skin ordinarily burns after 10 minutes in the sun (a factor of 15 times longer) International Journal of Pharmaceutical Research and Applications Volume 8, Issue 2 Mar-Apr 2023, pp: 1151-1156 www.ijprajournal.com ISSN: 2249-7781 https://www.fda.gov/about-fda/center-drug-evaluation-and-research-cder/sun-protection-factor-spf Abnormalities in Skin Pigmentation nevus (mole) albinism vitiligo freckles benign localized inability to produce condition in which there accumulation of overgrowth of melanin (genetic) is a partial or complete melanocytes in patches melanocytes loss of melanocytes (genetic) from patches of skin (autoimmune; body attacks melanocytes) Quick review! What is the largest organ of the body? Which part of the body has the thinnest layer of skin? Which part of the body has the thickest layer of skin? What are the three pigments that affect your skin color?  Subcutaneous Layer Subcutaneous layer (also called hypodermis) is not part of the skin but, among its functions, it attaches the skin to the underlying tissues and organs; Functions: insulation, protection of muscles from physical trauma, contains blood vessels to supply the skin Detects external pressure to the skin through the lamellated (pacinian) corpuscles What type of cells are present hypodermis? Note: The hypodermis is made of (hypo= below) connective tissue. Accessory Structures of the Skin: 1. Hair 2. Skin Glands 3. Nails Hair (Pili) ❏ Composition: columns of ❏ Parts: dead, keratinized epidermal shaft - projects above the cells surface of the skin root - penetrates into the ❏ Functions: dermis protection hair follicle - surrounds the reduction of heat loss roots sensing light touch contains sebaceous gland arrector pili (muscle) hair root plexus (nerve) Arrector Pili Muscle contracts under physiological or emotional stress, such as cold or fright pulls the hair shafts perpendicular to the skin surface goose bumps” or “gooseflesh” happen because the skin around the shaft forms slight elevations Alopecia Defined as partial or complete lack of hair Factors: illness, age, genetics, gender, severe emotional stress, diet Chemotherapeutic agents - interrupt the life cycle of rapidly dividing cells. Cells in the hair matrix are rapidly dividing - this is why those undergoing chemotherapy experience alopecia *Normal hair loss : 70–100 hairs per day Skin Glands 1. Sebaceous glands (oil glands) - secrete sebum 2. Sudoriferous glands (sweat glands) - secrete sweat 3. Ceruminous glands - secrete earwax Sebaceous Glands (oil glands) ❏ secrete an oily substance called sebum ❏ Functions: ❏ prevents dehydration of hair and skin ❏ inhibits growth of certain bacteria ❏ may produce acne, if clogged Summary of Functions of the Skin 1. regulation of body temperature liberating sweat at its surface and by adjusting the flow of blood in the dermis 2. blood reservoir 3. protection 4. cutaneous sensations 5. excretion and absorption - about 400 mL H2O/day evaporates a. water-soluble substances: negligible absorption b. some lipid-soluble materials (steroids, organic solvents): penetrate the skin 6. synthesis of vitamin D - requires UV rays (10-15 mins 2x a week) Wound Healing  Examples: Abrasions and Minor Burns 1. Basal cells of the epidermis surrounding the wound break contact with the basement membrane 2. The cells then enlarge and migrate across the wound 3. A hormone called “epidermal growth factor” stimulates cell division to create another layer growth factor - any of a group of proteins that stimulate the proliferation of specific tissues Quick review! A condition marked by partial or complete loss of melanocytes Part of the hypodermis that detects external pressure Names of the muscle and nerve ending found in the hair follicle