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Chapter 6

(Integument)

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Introduction to the Integumentary System

• Integument = skin• Integumentary system

= skin and its appendages– Appendages

• Hair• Nails• skin glands

– (sweat and sebaceous)

• PRIMARY FUNCTION: Protection

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Cutaneous Membrane Structure

• The skin is called the cutaneous membrane

• Two primary layers

– Epidermis

– Dermis

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EPIDERMIS• FEATURES

– Outer, Thinner Layer of Skin– Tissue Type

• Membranous Epithelium– (Stratified Squamous Epithelium‑Keratinized)

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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)

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3 CELL TYPES: MELANOCYTES

• MELANOCYTES - Produce Melanin

•Functions of Melanin–Responsible for Color of Skin, Hair, and Eyes

–Filters UV Light

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3 CELL TYPES: LANGERHANS• LANGERHAN'S CELLS

– Provide Defense against Foreign Invaders (Work with the Immune System)

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EPIDERMAL CELL LAYERS

• 5 Layers

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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

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CELL LAYERS ‑ STRATUM LUCIDUM

• 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)

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CELL LAYERS ‑ STRATUM GRANULOSUM

• STRATUM GRANULOSUM– "Granular Layer": Cells

in this Layer are Filled with Granules (Keratin Precursor)

– Keratinization Begins in this Layer

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CELL LAYERS ‑ STRATUM SPINOSUM

• 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)

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CELL LAYERS ‑ STRATUM BASALE

• STRATUM BASALE– "Base Layer": The

Innermost Layer of Epidermis

– Mitosis Occurs in this Layer

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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

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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

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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

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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

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DERMIS• FEATURES

– Inner, Thicker Layer of Skin– Tissue Type: Connective Tissue– Called "True Skin" (Thicker and Gives

Strength to Skin)

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STRUCTURES PRESENT IN THE DERMIS

• SENSORY

RECEPTORS

(Skin Functions as a

Sense Organ)– Specialized Nerve

Endings for • Hot

• Cold

• Pressure

• Pain

• Touch

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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"

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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)

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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

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Dermis is composed of 2 layers

• Papillary layers – dermal papillae

show through making fingerprints

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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

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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.

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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.

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Dermal Growth and Repair-Reticular Layer

• Elastic Fibers:– If overstretched

and torn, forms stretch marks.

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Tattoo pigment is usually black and is inert and non- polarizable; however, red tattoo pigment often contains

cinnabar (which has mercury in it).

Epidermis

Dermis

Tattoo Pigment

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Subcutaneous Layer

• Subcutaneous Layer– Hypodermis– superficial fascia)– Tissue type: connective

• loose areolar• adipose

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SKIN LAYERS-ReviewPrimary 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)

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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)

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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)

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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)

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THE SKIN’S FUNCTIONS: Sensations

• SENSATION– Skin Functions as a

Sense Organ for the Sensations of Hot, Cold, Pressure, Pain, and Touch - D/T Sensory Receptors in the Dermis

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THE SKIN’S FUNCTIONS: Movement

– 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

Watch:

Ehler’s Danlos syndrome

Characterized by stretchy skin and loose joints

MOVEMENT WITHOUT INJURY

Collagen

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Mutations in amino acid sequence causes defects in collagenthat can cause problems in these areas:

Collagen & Aging

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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

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THE SKIN’S FUNCTIONS: Excretion

• EXCRETION– Skin Functions as an

Excretory Organ D/T Sweat Glands Located in the Dermis

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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)

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THE SKIN’S FUNCTIONS: Immunity

• IMMUNITY– Skin Works With the

Immune System to Defend Against Microorganisms D/T Langerhans Cells in the Epidermis and Phagocytes

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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

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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.

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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.

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THE SKIN’S FUNCTIONS: Temperature Control

• HOMEOSTATIC CONTROL OF BODY TEMPERATURE– MECHANISM

INVOLVED WHEN BODY TEMPERATURE INCREASES

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THE SKIN’S FUNCTIONS: Temperature Control

– HOMEOSTATIC CONTROL OF BODY TEMPERATURE

• MECHANISM INVOLVED WHEN BODY TEMPERATURE DECREASES

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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.

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Burns-1st degree

• 1st degree– causes minor discomfort– some reddening– typical sunburn– Peeling– no blistering.

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Burns-2nd degree

• 2nd degree– involves the deep

epidermal layers– and some dermal

layers– may damage sweat

glands, etc– blistering– swelling– scarring.

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Burns-3rd degree

• 3rd degree burns– full-thickness

burns– complete

destruction of dermis and epidermis

– no pain due to destruction of nerve endings

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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.

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Rule of Nines

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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

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Appendages: Hair-Germinal Matrix

– 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.

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Appendages: Hair-Papilla, Root, Shaft

• HAIR PAPILLA– 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

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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

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Appendages: Hair-Sebaceous Glands

• 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

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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

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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

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Appendages: Skin Glands

• Sebaceous glands – Oil glands; sebum (oil) has antifungal and antibacterial properties

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Appendages: Skin Glands

• Ceruminous glands – specially modified sweat glands; found in external ear canals; produce cerumen (wax)