Chapter 6 (Integument) SKIN 3/28/2017

Introduction to the Integumentary System Integument = skin Integumentary system = skin and its appendages Appendages Hair Nails skin glands (sweat and sebaceous) PRIMARY FUNCTION: Protection 3/28/2017

Cutaneous Membrane Structure The skin is called the cutaneous membrane Two primary layers Epidermis Dermis 3/28/2017

EPIDERMIS FEATURES Outer, Thinner Layer of Skin Tissue Type Membranous Epithelium (Stratified Squamous Epithelium‑Keratinized) 3/28/2017

3 CELL TYPES: KERATINOCYTES Most Numerous and Important Cells in the Epidermis Filled with (or in the Process of Becoming Filled with) Keratin (Keratinization) Keratin Strong Protein Protects and Waterproofs the Skin Keratinization Process by Which Cells in the Epidermis Become Filled with Keratin and Moved to the Skin's Surface (Cells Die in the Process) 3/28/2017

3 CELL TYPES: MELANOCYTES MELANOCYTES - Produce Melanin Functions of Melanin Responsible for Color of Skin, Hair, and Eyes Filters UV Light 3/28/2017

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3 CELL TYPES: LANGERHANS LANGERHAN'S CELLS Provide Defense against Foreign Invaders (Work with the Immune System) 3/28/2017

EPIDERMAL CELL LAYERS 5 Layers 3/28/2017

CELL LAYERS ‑ STRATUM CORNEUM 1st layer STRATUM CORNEUM "Hardened Layer": Cells in this Layer are Totally Filled with Keratin (Replaces the Cytoplasm) Known as the Barrier Area Cells at the Surface of this Layer are Dead 3/28/2017

CELL LAYERS ‑ STRATUM LUCIDUM "Clear Layer": Cells in this Layer have a Clear Appearance (Keratin Precursor) Only Present in Thick Skin (palms of hands and soles of feet) 3/28/2017

CELL LAYERS ‑ STRATUM GRANULOSUM "Granular Layer": Cells in this Layer are Filled with Granules (Keratin Precursor) Keratinization Begins in this Layer 3/28/2017

CELL LAYERS ‑ STRATUM SPINOSUM "Spiny Layer": Cells in this Layer Have an Irregular Shape (Plasma Membranes Modified To Hold Tightly Together) Rich in RNA (Preparation for Keratinization) 3/28/2017

CELL LAYERS ‑ STRATUM BASALE "Base Layer": The Innermost Layer of Epidermis Mitosis Occurs in this Layer 3/28/2017

CELL LAYERS ‑ 2 LAYERS MAKE THE GROWTH LAYER STRATUM GERMINATIVUM NOT ANOTHER LAYER, ACTUALLY COMPOSED OF 2 EXISTING LAYERS The growth layer Composed of s. spinosum and s. basale 3/28/2017

EPIDERMAL GROWTH AND REPAIR TURNOVER (REGENERATION) TIME Time Required for Epithelial Cells to Form in the Stratum Basale and Migrate to the Skin's Surface Average Turnover Time = 35 Days (Maintains a Constant Skin Thickness Application: Shortened Turnover Time Results in Formation of Callus 3/28/2017

EPIDERMAL GROWTH AND REPAIR EPIDERMAL PROLIFERATING UNIT (EPU) Each Group of 8‑10 Basal Cells Along with the Vertical Columns of Cells Above (Up to the Skin's Surface) Epidermis Grows in Units ‑ Not as a Whole 3/28/2017

DERMAL ‑ EPIDERMAL JUNCTION The Union Between the Epidermis and the Dermis A Basement Membrane Functions: Tightly "Glues" the Epidermis to the Dermis Provides Support for the Epidermis Serves as a Partial Barrier Between the Epidermis and the Dermis 3/28/2017

DERMIS FEATURES Inner, Thicker Layer of Skin Tissue Type: Connective Tissue Called "True Skin" (Thicker and Gives Strength to Skin) 3/28/2017

STRUCTURES PRESENT IN THE DERMIS SENSORY RECEPTORS (Skin Functions as a Sense Organ) Specialized Nerve Endings for Hot Cold Pressure Pain Touch 3/28/2017

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STRUCTURES PRESENT IN THE DERMIS MUSCLE FIBERS ‑ 2 Types SKELETAL Located Only in the Dermis of the Face and Scalp Function: Voluntary Movement of the Face and Scalp SMOOTH ‑ ARRECTOR PILI MUSCLES Involuntary The Most Abundant of the 2 Types of Muscle Fibers Form Arrector Pili Muscles Produces "Goose Bumps" 3/28/2017

STRUCTURES PRESENT IN THE DERMIS HAIR FOLLICLES Tubes That Hold Hairs (More Detail with Hair) SWEAT, SEBACEOUS GLANDS Skin Glands (More Detail with Skin Glands) 3/28/2017

STRUCTURES PRESENT IN THE DERMIS BLOOD VESSELS The Dermis Contains an Extensive Network of Blood Vessels That Play an Important Role in Regulation of Body Temperature 3/28/2017

Dermis is composed of 2 layers Papillary layers dermal papillae show through making fingerprints 3/28/2017

Dermis is composed of 2 layers Reticular layer Inner, thicker layer dense network of collagenous and elastic fibers Contains muscle fibers hair follicles sweat and sebaceous glands blood vessels sense receptors 3/28/2017

Dermal Growth and Repair: Scars Dermis does not continually shed and regenerate itself. In the healing of a wound, fibroblasts reproduce and begin forming a dense mass of connective tissue fibers. If this fiber is not replaced by normal tissue, it remains a scar. 3/28/2017

Dermal Growth and Repair-Reticular Layer Collagenous fibers form Langer’s Lines the collagenous fibers that characterize the dermal layer line themselves up in lines (sometime called cleavage lines). If surgical incisions are made along these cleavage lines, there will be a less noticeable scar and healing will be much quicker. 3/28/2017

Dermal Growth and Repair-Reticular Layer Elastic Fibers: If overstretched and torn, forms stretch marks. 3/28/2017

Tattoo Pigment Epidermis Dermis Tattoo pigment is usually black and is inert and non- polarizable; however, red tattoo pigment often contains cinnabar (which has mercury in it). 3/28/2017

Subcutaneous Layer Subcutaneous Layer Hypodermis superficial fascia) Tissue type: connective loose areolar adipose 3/28/2017

SKIN LAYERS-Review Primary Layers Epidermis Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Dermal-Epidermal Junction (not a primary layer) Dermis Papillary Reticular Subcutaneous Layer (hypodermis; superficial fascia) Tissue type: connective (loose areolar and adipose) 3/28/2017

Skin Color Skin color is essentially determined by the quantity of melanin produced by melanocytes in the stratum basale. Determining Factors Number of melanocytes – all races have approximately the same number of melanocytes. Amount of melanin produced by melanocytes is determined by: Heredity – the primary factor Sunlight – sunlight increase melanin production Hormones – Adrenocorticotropic hormones (ACTH) and MSH (Melanocyte stimulating hormone) Age – Increase in age may also influence melanocyte activity (age spots, graying hair) Temporary Changes Amount of blood flow to skin, more = pinker Amount of oxygen in blood, less oxygen = blue (cyanosis) 3/28/2017

THE SKIN’S FUNCTIONS: Protection Protection From: Microbe infection (by layers of nonvascular keratinocytes) Harmful chemicals (by layers of nonvascular keratinocytes) Dehydration (by keratin) UV light (by melanin) Mechanical injury (by thick, strong dermis) 3/28/2017

THE SKIN’S FUNCTIONS: Protection SURFACE FILM A Thin Film of Materials That Covers the Skin’s Surface Consists of Secretions From Sweat and Sebaceous Glands As Well As Dead Epithelial Cells FUNCTIONS Barrier Antibacterial/Antifungal (D/T Chemical Components) Lubricates (D/T Oil) Hydrates (D/T Sweat) Buffers (D/T Chemical Components) 3/28/2017

THE SKIN’S FUNCTIONS: Sensations Skin Functions as a Sense Organ for the Sensations of Hot, Cold, Pressure, Pain, and Touch - D/T Sensory Receptors in the Dermis 3/28/2017

THE SKIN’S FUNCTIONS: Movement MOVEMENT WITHOUT INJURY Ehler’s Danlos syndrome Skin Allows Body Growth and Movement of the Body Without Injury to Underlying Tissues and Organs D/T Elasticity of the Dermis and SQ Layer Characterized by stretchy skin and loose joints Watch: 3/28/2017

Collagen Mutations in amino acid sequence causes defects in collagen that can cause problems in these areas: 3/28/2017

Collagen & Aging Collagen Theory of Aging with age, collagen gets older old collagen gets stiff and not as flexible causing problems such as: Hypertension- (vessels cant expand enough) organs malfunction (stiffness) hinders metabolic functions Wrinkles Due to changes in reduced collagen decreased protein synthesis affect collagen type 1 & 3 in dermis reduced elastin general atrophy in extracellular matrix due to reduced fibroblasts 3/28/2017

THE SKIN’S FUNCTIONS: Excretion Skin Functions as an Excretory Organ D/T Sweat Glands Located in the Dermis 3/28/2017

THE SKIN’S FUNCTIONS: Vitamin D VITAMIN D PRODUCTION (ENDOCRINE FUNCTION) Mechanism: Precursor Compound in Skin Cells Activated By UV Light  Transported By Blood to Liver, Kidney  Converted to Vitamin D (Needed for Calcium Absorption) Vitamin D Classifies Loosely as a Hormone) 3/28/2017

THE SKIN’S FUNCTIONS: Immunity Skin Works With the Immune System to Defend Against Microorganisms D/T Langerhans Cells in the Epidermis and Phagocytes 3/28/2017

THE SKIN’S FUNCTIONS: Homeostasis HOMEOSTASIS OF BODY TEMPERATURE Skin Helps to Maintain Constant Body Temperature (Sweat Glands and Blood Vessels) BASIC PRINCIPLE To Maintain a Constant Body Temperature: Heat Production Must Equal Heat Loss HEAT PRODUCTION: FROM FOOD CATABOLISM Nutrient Catabolism  Energy 1) Chemical (ATP) 2) Heat (Released) RELATES TO ACTIVITY Increased Activity  Increased Catabolism  Increased Heat Production Cells That Are the Most Active and Produce the Most Heat: Liver, Skeletal Muscle 3/28/2017

THE SKIN’S FUNCTIONS: Temperature Control-Heat Loss HEAT LOSS – 80% Occurs Through the Skin FROM EVAPORATION AND RADIATION Evaporation Vaporization of Liquid (Requires Heat Energy) Example: Evaporation of Sweat Most Impt. Way Heat Loss Occurs in Hot Temps. 3/28/2017

THE SKIN’S FUNCTIONS: Temperature Control-Heat Loss HEAT LOSS – 80% Occurs Through the Skin FROM EVAPORATION AND RADIATION Radiation Heat Transfer (Warmer  Cooler) Without Direct Contact Between 2 Objects Example: Dilation of Blood Vessels in the Dermis (Text) Most Impt. Way Heat Loss Occurs in Cool Temps. 3/28/2017

THE SKIN’S FUNCTIONS: Temperature Control HOMEOSTATIC CONTROL OF BODY TEMPERATURE MECHANISM INVOLVED WHEN BODY TEMPERATURE INCREASES 3/28/2017

THE SKIN’S FUNCTIONS: Temperature Control HOMEOSTATIC CONTROL OF BODY TEMPERATURE MECHANISM INVOLVED WHEN BODY TEMPERATURE DECREASES 3/28/2017

Burns Burns are classified based on depth 1st is just epidermal (top layer) 2nd is deeper, involves both dermal and epidermal layers. 3rd is deepest, involves epidermis, dermis, and sometimes deeper levels. 3/28/2017

Burns-1st degree 1st degree causes minor discomfort some reddening typical sunburn Peeling no blistering. 3/28/2017

Burns-2nd degree 2nd degree involves the deep epidermal layers and some dermal layers may damage sweat glands, etc blistering swelling scarring. 3/28/2017

Burns-3rd degree 3rd degree burns full-thickness burns complete destruction of dermis and epidermis no pain due to destruction of nerve endings 3/28/2017

Rule of 9s Estimation of body surface area is accomplished by the rule of 9s. Victim’s palm size is roughly 1% Of body surface. 3/28/2017

Rule of Nines 3/28/2017

Appendages: Hair-Follicle HAIR FOLLICLE & GERMINAL MATRIX Hair Follicle Tubelike, Holds Hair Root Formation: Cells from the Epidermis Push Down into the Dermis Follicle Wall: 2 Layers 1) Outer: Dermal Root Sheath 2) Inner: Epithelial Root Sheath 3/28/2017

Appendages: Hair-Germinal Matrix Cap-shaped Cluster of Cell at Bottom of Hair Follicle Formed from stratum germinativum Forms the Hair (Mitosis and Keratinzation) Papilla’s (from dermis) capillaries nourish g. matrix-next slide. 3/28/2017

Appendages: Hair-Papilla, Root, Shaft Dermis that Protrudes into the Germinal Matrix Contains Blood Vessels HAIR ROOT Hidden Portion of the Hair (Lies in Hair Follicle) HAIR SHAFT Visible Portion of the Hair 3/28/2017

Appendages: Hair-Cortex & Medulla CORTEX AND MEDULLA OF HAIR Medulla: Inner Core of the Hair Cortex: Outer Portion of the Hair (Cells Contain Melanin and Keratin) Cuticle: Covers Cortex 3/28/2017

Appendages: Hair-Sebaceous Glands Oil Glands; Part of Hair Follicle Secrete Sebum Directly into Follicle Functions of Sebum: 1) Lubricates Skin, Hair 2) Antifungal Located in Dermis in All Areas Except Palms and Soles 3/28/2017

Appendages: Nails Nail body – visible part of the nail Heavily keratinized cells. Root – invisible part found behind cuticle Cuticle – fold of skin Lunula – moon shape, Cells beneath are stratus germinativum that produce nail cells by mitosis. Nail bed – cells supporting the nail 3/28/2017

Appendages: Skin Glands Sweat Glands most numerous skin glands produces watery liquid in which waste materials such as ammonia and urea and salts are excreted bacterial growth causes it to stink Two types: Eccrine most common type Apocrine deep in the subcutaneous layer; armpit, areola, around anus 3/28/2017

Appendages: Skin Glands Sebaceous glands – Oil glands; sebum (oil) has antifungal and antibacterial properties 3/28/2017

Appendages: Skin Glands Ceruminous glands – specially modified sweat glands; found in external ear canals; produce cerumen (wax) 3/28/2017