2.2 – Integumentary System

Chapter 5

Skin Disorder Mini-Project

The Integumentary System

Written Response #12

• In your notebook, complete the following items:1. Drawing of a cross section of skin that includes the

layers of the skin labeled (epidermis, dermis, hypodermis)

2. Drawings of the four types of membranes and their function.

Types of Membranes

• Serous Membranes: line body cavities that lack opening to the outside.• Parietal Pleura

• Parietal Peritoneum

• Visceral Pleura

• Visceral Peritoneum

Types of Membranes

• Mucous Membranes: line cavities and tubes that open to the outside of the body.• Nasal cavities

• Tubes of the digestive system

• Respiratory

• Urinary

• Reproductive Systems

Types of Membranes

• Synovial membranes: form the inner linings of the joint cavities between the ends of bones at freely moving joints (“synovial joints”).• Elbow

• Wrist

• Ankle

• Knee

Types of Membranes

• Cutaneous Membrane: skin.

Blank Skin Diagram - Handout

• Complete diagram, glue in notebook, and begin studying the structure of skin.

The Integumentary System

• Composed of the skin, sweat and oil glands, hair, and nails.

• Varies in thickness from 1.5 to 4.0 mm.

• Composed of three distinct layers: epidermis, dermis, and hypodermis (superficial fascia)

Functions of Skin

• Protection• Cushions and insulates and is waterproof

• Protects from chemicals, heat, cold, bacteria

• Screens UV

• Synthesizes vitamin D with UV

• Regulates body heat

• Prevents unnecessary water loss

• Sensory reception (nerve endings)

Epidermis

• Outermost layer.

• Composed mostly of keratinized stratified squamous epithelium.

• Contains four distinct cell types and four to five distinct layers.

Written Response #13: Draw and complete the following chart in your notebook.

Skin Cell Type FunctionLocation within the

skinDrawing of cell/Cell

Location

Keratinocytes

Melanocytes

Langerhans' Cell

Merkel Cells

Cell Types of the Epidermis

• Keratinocytes – produce keratin, a fibrous protein that give the epidermis its protective properties. • These cells are tightly connected by desmosomes.

• Arise from the stratum basale are pushed upward and continuously become more keratinized.

• Undergo continuous mitosis.

• Those on the surface of the skin are dead. • Millions rub off per day.

• Friction may lead to a thickening of the cells known as a callus.

Cell Types of the Epidermis

• Melanocytes – synthesize melanin.• Located at the deepest layer of the epidermis (stratum

basal).

• The melanin is transferred to the keratocytes.

• Protects against UV damage.

Cell Types of the Epidermis

• Langerhans’ cells - arise from the bone marrow.• Act as macrophages that activate the immune system.

• Merkel cells - present at the junction of the epidermis and dermis. • Associated with sensory receptors.

Written Response #14

1. Explain how the epidermis is formed.

2. Distinguish between the stratum basale and the stratum corneum.

3. What is the function of melanin?

4. What factors influence skin color?

Layers of the Epidermis

• Thick skin• Has 5 strata.

• Found on palms, fingertips, soles

• Thin skin• Has only 4 strata.

• Layers are visibly thinner.

• The stratum lucidum is absent

Poster – Layers of the Epidermis

• Posters should be as detailed as possible with color• Draw a picture that compares thick Skin and thin Skin.

• In the picture, label each layer of skin, and give a description of the various layers.

• If layers are different between the two types of cells indicate this with the description of each layer in a different color.

• In both pictures include the dermis and the hypodermis.

Layers of the Epidermis

• Stratum Basale: deepest layer. • Attached to the dermis.

• Sometimes called the stratum germinativum because of the constant mitosis that occurs there.

• Made of a single row of keratinocytes.

Layers of the Epidermis

• Stratum Spinosum: several layers thick. • Contain many intermediate filaments.

• Consist mainly of keratin like filaments.

• Resist tension.

• Melanin granules and Langerhan’s cells are abundant in this layer.

• Stratum Granulosum: 3-5 cell layers thick.• Keratinocytes become more flattened and the cells contain

more keratin and lamellated granules (prevent water loss).

• Stratum Lucidum—thin layer of dead keratinocytes. • Present only in thick skin. (Due to friction in the skin.)

Layers of the Epidermis

• Stratum Corneum—Outermost layer. 20-30 cell layers thick. • Cells have thick cell membranes and a great deal of

keratin.• Cells are referred to as cornified.

Epithelium: layers (on left) and cell types (on right)

Written Response #15

1. What kinds of tissues make up the dermis?

2. What are the functions of these tissues?

3. What are the functions of the subcutaneous layer?

Dermis

• Strong, flexible connective tissue: your “hide”

• Cells: fibroblasts, macrophages, mast cells, WBCs

• Fiber types: collagen, elastic, reticular

• Rich supply of nerves and vessels

• Critical role in temperature regulation (the vessels)

Layers of the Dermis

• Consists of two layers:• Papillary layer which consists

of:• areolar connective tissue that

is heavily vascularized. • dermal papillae

• In some areas these lie on top of the dermal ridges. Cause the epidermal ridges that cause fingerprints.

• capillary loops• Meissner’s corpuscles.

• Reticular layer: dense irregular connective tissue.

• Contains all the cells of connective tissue.

• Flexure lines – layering in the dermis responsible for visible markings on the skin.

Epidermis or dermis: Which one makes the difference?

Skin Features

• Finger prints, foot prints, etc.• Dermal papillae lie atop dermal ridges• Elevate the overlying epidermis into

epidermal ridges• Are “sweat films” because of sweat

pores

• Genetically determined (Twins to don’t share finger prints.

• Flexion creases• Deep dermis, from continual folding

• Fibers• Collagen: strength and resilience• Elastic fibers: stretch-recoil

• Striae: stretch marks (Tearing of the dermis.)

• Tension lines (or lines of cleavage)• The direction the bundles of fibers

are directed

The dermis is the receptive

site for the pigment of tattoos

What determines skin color?

• Skin color is determined by:• Melanin

• Carotene

• Hemoglobin.

Hypodermis

• “Hypodermis” (Greek) = below the skin

• “Subcutaneous” (Latin) = below the skin

• Also called “superficial fascia”• “fascia” (Latin) =band; in anatomy: sheet of connective

tissue

• Fatty tissue which stores fat and anchors skin (areolar tissue and adipose cells)

• Different patterns of accumulation (male/female)

Written Response #16

1. Explain how a hair forms

2. What is the function of the sebaceous glands?

3. Distinguish between the eccrine and aprocrine sweat glands.

Sebaceous (Oil) Glands

• Entire body except palms and soles• Produce sebum by

holocrine secretion

• Oils and lubricates

• Usually secreted into hair follicles.

• Bactericidal

Sweat Glands

• Entire skin surface except nipples and part of external genitalia• Prevent overheating

• 500 cc to 12 l cc/day! (is mostly water)

• Humans are only mammals that have sweat glands.

• Produced in response to stress as well as heat

Types of Sweat Glands

• Eccrine or merocrine• Most numerous• True sweat: 99% water, some salts, traces of waste• Open through pores

• Apocrine• Axillary, anal and genital areas only• Ducts open into hair follices• The organic molecules in it decompose with time - odor

• Modified apocrine glands• Ceruminous – secrete earwax• Mammary – secrete milk

Hair and Hair Follicles: Complex

• Derived from epidermis and dermisEverywhere but palms, soles, nipples, parts of genitalia• “arrector pili” is smooth

muscle

• Hair bulb: epithelial cells surrounding papilla

• Hair papilla is connective tissue

*

• Functions of hair• Warmth – less in humans than other mammals• Sense light touch of the skin• Protection - scalp

• Parts• Root imbedded in skin• Shaft projecting above skin surface

• Make up of hair – hard keratin• Three concentric layers

• Medulla (core)• Cortex (surrounds medulla)• Cuticle (single layers, overlapping)

• Types of hair• Vellus: fine, short hairs• Intermediate hairs • Terminal: longer, courser hair

• Hair growth: averages 2 mm/week• Active: growing• Resting phase then shed

• Hair loss• Thinning – age and genetic related.• Male pattern baldness

• Hair color• Amount of melanin for black or brown; distinct form of melanin for red• White: decreased melanin and air bubbles in the medulla• Genetically determined though influenced by hormones and

environment

Nails Posters

• Draw, label and describe the various parts of a nail. (Two Pictures Top – Side View)

• Include the following pars of the nail:• Nail Bed

• Nail Matrix

• Lunula

• Cuticle

• Free edge

• Body

• Laternal Nail Fold

Nails

• Modification of the epidermis

• Composed of keratin.

• Composed of a free edge, body, and a root.

• Anatomy of a Nail• Nail Bed - epidermis under the nail.

• Nail Matrix - growth occurs here.

• Lunula – visible portion of the root.

• Cuticle – skin that over laps the nail.

Functions of the Integument

• Chemical barriers—acid mantle, human defensin

• Biological Barriers—Langerhan’s cells and macrophages.

• Physical barrier• Some substances can cross the skin.

• Lipid soluble substances.

• Oleoresins—poison ivy.

• Organic solvents.

• Salts of heavy metals

Functions of the Integument

• Temperature Regulation• Sweat glands

• Vasodilation and vasoconstriction

• Metabolic Functions• Vitamin D synthesis

• Blood Reservoir• Shunts more blood into the circulation when needed.

• Excretion

Tumors of the skin

• Benign, e.g. warts

• Cancer – associated with UV exposure (also skin aging)• Aktinic keratosis - premalignant

• Basal cell - cells of stratum basale

• Squamous cell - keratinocytes

• Melanoma – melanocytes: most dangerous; recognition:• A - Asymmetry

• B - Border irregularity

• C - Colors

• D - Diameter larger than 6 mm

Skin Cancer

Basal cell carcinoma

Squamous

cell

carcinoma

Melanoma

Disorders of the Integumentary System• Burns

• Threat to life• Catastrophic loss of body fluids

• Dehydration and fatal circulatory shock

• Infection

• Types• First degree – epidermis: redness (e.g. sunburn)

• Second degree – epidermis and upper dermis: blister

• Third degree - full thickness

• Infections

• Skin cancer

Burns

• First-degree: epidermis only; redness

• Second-degree: epidermis and dermis, with blistering

• Third-degree: full thickness, destroying epidermis, dermis, often part of hypodermis

Critical burns

• Over 10% of the body has third-degree burns

• 25% of the body has second-degree burns

• Third-degree burns on face, hands, or feet

• Estimate by “rule of 9’s”

Written Response #17

1. Describe how inflammation helps a wound to heal.

2. Distinguish between the activities necessary to heal a wound in the epidermis from those necessary to heal a wound in the dermis.

3. Explain the role of phagocytic cells in wound healing.

4. Define granulation.

Wound Healing Poster

• Create a poster that compares Epidermal Wound Healing to Deep wound healing.

• Draw the different steps of wound healing for both situations and describe what is occurring in each step of the healing process.

• Stages of Epidermal Wound Healing

1. Division of Basal Cell Epithelial

2. Thickening of Epidermis

• Stages of Deep Wound Healing

1. Inflammatory phase2. Migratory phase3. Proliferative phase4. Maturation phase

Epidermal Wound Healing

Deep Wound Healing

• Injury extends into dermis & hypodermis

• Scar tissue is formed• Some normal function

lost

• Occurs in four phases1. Inflammatory phase

2. Migratory phase

3. Proliferative phase

4. Maturation phase

Inflammatory Phase

• Blood clot forms loosely uniting wound edges

• Inflammation occurs• Eliminates microbes, foreign material, and dying tissue

• Increases diameter of local blood vessels• Enhancing delivery of nutrients, immune cells, and fibroblasts

Migratory Phase

• Clot dries into scab

• Epithelial cells migrate beneath scab and bridge wound

• Fibroblasts migrate and lay down collagen fibers and glycoproteins in dermis

• New blood vessels grow

• Tissue called granulation tissue during this phase destined to become scar tissue

Proliferative Phase

• Extensive growth of epithelium

• Deposition of collagen in random patterns by fibroblasts

• Continued growth of blood vessels

Maturation Phase

• Scab sloughs off once epidermis restored to normal thickness

• Granulation tissue developing into scar tissue

• Fibroblasts decrease in number

• Blood vessels restored to normal

• Scar tissue formation called fibrosis

• Elevated scars called • Hypertrophic scars

• If contained within sight of original wound

• Keloid scars • If extended beyond original

wound