Essentials of Human Anatomy & Physiology

Seventh Edition

Elaine N. Marieb

Chapter 4

Skin and Body Membranes

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Slides 4.1 – 4.44

Skin and Body Membranes

Lecture Slides in PowerPoint by Jerry L. Cook

Skin and Body MembranesSkin and Body Membranes

Body membranes cover surfaces, linebody cavities, and form protectivesheets around organs

Function of body membranes

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Function of body membranes

Line or cover body surfaces

Protect body surfaces

Lubricate body surfaces

Classification of Body MembranesClassification of Body Membranes

Epithelial membranes

Cutaneous membrane

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Mucous membrane

Serous membrane

Connective tissue membranes

Cutaneous MembraneCutaneous Membrane

Cutaneous membrane = skin

A dry membrane

Outermost protective boundary

Superficial epidermis

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Superficial epidermis

Keratinized stratifiedsquamous epithelium

Underlying dermis

Mostly dense (fibrous)connective tissue

Figure 4.1a

Mucous MembranesMucous Membranes Surface epithelium

Type depends on site

Underlying loose connective tissue(lamina propria)

Lines all body cavities that

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Figure 4.1b

Lines all body cavities thatopen to the exterior bodysurface

Often adapted for absorptionor secretion

Wet membranes bathed insecretions

Serous MembranesSerous Membranes Surface simple squamous

epithelium

Underlying areolar connectivetissue

Lines open body cavities that

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Figure 4.1c

Lines open body cavities thatare closed to the exterior ofthe body

Occur in pairs – parietal andvisceral

Serous layers separated byserous fluid

Serous MembranesSerous Membranes

Specific serous membranes

Peritoneum

Abdominalcavity

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Pleura

Around thelungs

Pericardium

Around theheart

Figure 4.1d

Connective Tissue MembraneConnective Tissue Membrane

Synovial membrane

Areolar connectivetissue only

Lines fibrous capsules

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Lines fibrous capsulessurrounding joints

Line small sac ofconnective tissuecalled bursae and thetube-like tendonsheaths

Figure 4.2

Integumentary SystemIntegumentary System

Skin (cutaneous membrane)

Skin derivatives

Sweat glands

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Sweat glands

Oil glands

Hairs

Nails

Skin FunctionsSkin Functions

Protects deeper tissues from:

Mechanical damage

Chemical damage

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Chemical damage

Bacterial damage

Thermal damage

Ultraviolet radiation

Desiccation

Skin FunctionsSkin Functions

Protective and cushioning

Waterproof

Aids in heat regulation

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Aids in heat regulation

Aids in excretion of salts, urea and uricacid

Synthesizes vitamin D

Contains sensory receptors

Skin StructureSkin Structure

Epidermis – outer layer

Stratified squamous epithelium

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Often keratinized (hardened by keratin)

Dermis

Dense connective tissue

Both firmly connected but can separate suchas in a blister

Skin StructureSkin Structure

Deep to dermis is the hypodermis

Not part of the skin

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Not part of the skin

Anchors skin to underlying organs

Composed mostly of adipose tissue

Serves as shock absorber and insulationfor deeper tissues

Layer of EpidermisLayer of Epidermis

Stratum basale – deepest layer

Cells undergoing mitosis

Lies next to dermis and receives nutrientsfrom the dermis by diffusion

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from the dermis by diffusion

Stratum spinosum – old stratum basale cells

Stratum granulosum – old stratum spinosumcells

Layer of EpidermisLayer of Epidermis

Stratum lucidum

Occurs only in thick, hairless skin

Stratum corneum

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Shingle-like dead cells that are ¾ of theepidermal thickness

Completely filled with keratin cells calledcornified or horny cells

MelaninMelanin

Pigment (melanin) produced by melanocytes

Color is yellow to brown to black

Melanocytes are mostly in the stratum

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Melanocytes are mostly in the stratumbasale

Amount of melanin produced depends upongenetics and exposure to sunlight

DermisDermis –– the “hide”the “hide” Two layers

Papillary layer

Projections called dermal papillae

Pain receptors and touch receptors

Capillary loops for nutrients

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Capillary loops for nutrients

Result in fingerprints

Reticular layer

Blood vessels

Sweat and oil glands

Nerve receptors

DermisDermis –– the “hide”the “hide”

Both collagen and elastic fibers are found inthe dermis

Collagen – responsible for the toughnessof the dermis and for binding water to keepit hydrated

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Elastic fibers – give skin elasticity when weare young but lessens as we age alongwith collagen

Lots of blood vessels play a role inmaintaining body temperature

Skin StructureSkin Structure

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Figure 4.4

Normal Skin Color DeterminantsNormal Skin Color Determinants

Melanin – amount and kind

Yellow, brown or black pigments

Carotene

Orange-yellow pigment from somevegetables

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Orange-yellow pigment from somevegetables

Hemoglobin

Red coloring from blood cells in dermiscapillaries

Oxygen content determines the extent of redcoloring

Normal Skin Color DeterminantsNormal Skin Color Determinants

Redness or erythema – blushing

Pallor or blanching – pale from fear oranemia, low blood pressure, or impairedblood flow

Jaundice or yellow cast – liver disorder

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Jaundice or yellow cast – liver disorderwhere excess bile pigments are absorbed inthe blood

Bruises or black-and-blue marks – whereblood has escaped from vessels and clottedin the tissue spaces – called hematomas

Appendages of the SkinAppendages of the Skin

Arise from the epidermis and play a rolein maintaining homeostasis of the body

Cutaneous glands – exocrine glands

Release their secretions to the skin

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Release their secretions to the skinsurface via ducts

Sebaceous glands and sweatglands

Appendages of the SkinAppendages of the Skin

Sebaceous glands

Produce oil - sebum

Lubricant for skin

Kills bacteria

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Kills bacteria

Prevents hair from becoming brittle

Most with ducts that empty into hair follicles

Glands are activated at puberty

Appendages of the SkinAppendages of the Skin

Sweat glands – sudoriferous glands

Widely distributed in skin

Two types

Eccrine

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Eccrine

Open via duct to pore on skin surface

Apocrine

Ducts empty into hair follicles

Sweat and Its FunctionSweat and Its Function Composition

Mostly water with some salts and vitamin C

Some metabolic waste and lactic acid

Fatty acids and proteins (apocrine only), whichmay have a milky or yellowish color

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Function

Helps dissipate excess heat – eccrine only

Excretes waste products

Acidic nature inhibits bacteria growth

Odor is from associated bacteria living offproteins and fats

Appendages of the SkinAppendages of the Skin Hair

Serves a few minor protective functions

Used to serve as insulation and still does insome animals

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Produced by a hair follicle – flexible epithelialstructure

Part of the hair enclosed in the follicle is theroot

Part projecting from the surface of the scalpis the shaft

Appendages of the SkinAppendages of the Skin

Hair

Produced byhair bulb matrix

Consists of hard

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Consists of hardkeratinizedepithelial cells

Melanocytesprovide pigmentfor hair color Figure 4.7c

Hair AnatomyHair Anatomy Central core called the medulla

Cortex surrounds medulla

Cuticle on outside of cortexformed from a single layer of cellsthat overlap like shingles on a

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Figure 4.7b

that overlap like shingles on aroof to keep hairs separated

Most heavily keratinized to providestrength

Worn more at tips to cause splitends

Associated Hair StructuresAssociated Hair Structures

Hair follicle

Dermal (provides bloodvessels) and epidermal sheathsurround hair root

Arrector pilli

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Figure 4.7a

Arrector pilli

Smooth muscle cause the hairto stand up – goose bumps

Sebaceous (oil) gland

Sweat gland

Nail StructuresNail Structures

Each nail has threeparts

Free edge

Body

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Body

Root of nail

Eponychium – proximalnail fold that projects ontothe nail body – oftencalled cuticle

Figure 4.9

Appendages of the SkinAppendages of the Skin

Nails

Scale-like modifications of the epidermis

Heavily keratinized

Stratum basale extends beneath the nail bed

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Stratum basale extends beneath the nail bed

The thickened proximal area called the nail matrixis responsible for nail growth

Lack of pigment makes them colorless

Appear pink due to blood vessels underneath

White crescent – lunula – thickened nail matrix

Skin Homeostatic ImbalancesSkin Homeostatic Imbalances Infections

Athletes foot – tinea pedis

Caused by fungal infection on feet

Boils and carbuncles

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Caused by bacterial infection –Staphylococcus aureus – in hair follicles andsebaceous glands

Cold sores – fever blisters

Caused by herpes simplex viral infectionusually on lips and in oral mucosa of themouth

Skin Homeostatic ImbalancesSkin Homeostatic Imbalances Infections and allergies

Contact dermatitis

Exposures to certain chemicals cause allergicreaction

Impetigo

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Impetigo

Pink, water-filled, raised lesions around the mouthcaused by staphylococcus bacterial infection

Psoriasis

Cause is unknown but chronic

Triggered by trauma, infection, stress

Skin Homeostatic ImbalancesSkin Homeostatic Imbalances

Burns

Tissue damage and cell death caused by heat,electricity, UV radiation, or chemicals

Nearly every body system is affected when skinis severely damaged

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is severely damaged

Associated dangers

Dehydration

Electrolyteimbalance

Circulatoryshock

Infection

Rules of NinesRules of Nines

Way to determine theextent of burns

Body is divided into 11areas for quick estimation

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areas for quick estimation

Each area representsabout 9%

Rule of nines

Classified according to theirseverity (depth)

Severity of BurnsSeverity of Burns

First-degree burns

Only epidermis is damaged

Skin is red and swollen

Partial-thickness burn that heals quickly

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Partial-thickness burn that heals quickly

Severity of BurnsSeverity of Burns

Second degree burns

Epidermis and upper dermis are damaged

Skin is red with blisters

Partial-thickness burn that heals w/o scar

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Partial-thickness burn that heals w/o scar

Severity of BurnsSeverity of Burns Third-degree burns

Destroys entire skin layer

Burn is gray-white or black

Nerve endings destroyed so not painful

Full-thickness burn that does not heal and grafting is

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Full-thickness burn that does not heal and grafting isnecessary

Severity of BurnsSeverity of Burns

•Fourth-degree burns•Extend through the skin to injure muscle,ligaments, tendons, nerves, blood vessels, andbones•These burns always require medical treatment

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•These burns always require medical treatment

Critical BurnsCritical Burns

Burns are considered critical if:

Over 25% of body has second degreeburns

Over 10% of the body has third degree

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Over 10% of the body has third degreeburns

There are third degree burns of the face,hands, or feet

Skin CancerSkin Cancer

Cancer – abnormal cell mass

Two types

Benign

Does not spread (encapsulated)

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Does not spread (encapsulated)

Malignant

Metastasized (moves) to other parts ofthe body

Skin cancer is the most common type ofcancer

Skin Cancer TypesSkin Cancer Types

Basal cell carcinoma

Least malignant

Most common type

Arises from stratum basale that no longer makeskeratin and stays in place

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keratin and stays in place

Squamous cell carcinoma

Arises from stratum spinosum

Metastasizes to lymph nodes

Early removal allows a good chance of cure

Skin Cancer TypesSkin Cancer Types

Malignant melanoma

Most deadly of skin cancers

Cancer of melanocytes

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Cancer of melanocytes

Metastasizes rapidly to lymph and bloodvessels

Detection uses ABCD rule

ABCD RuleABCD Rule

A = Asymmetry

Two sides of pigmented mole do not match

B = Border irregularity

Borders of mole are not smooth

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Borders of mole are not smooth

C = Color

Different colors in pigmented area

D = Diameter

Spot is larger then 6 mm in diameter