ESPIRATORY INFEC'I'I©N 5

IONS OF MICROORGANISMS - BACTERIA, VIRUSESÿ AND FUNGI - populate the

)uring inhalation, these minute organisms can easily enter the air passageslead to the lungs, maldng respiratory infections quite common. Infections

Le upper airways, also known as upper respiratory tract infections, may cause

[d illness, such as a common cold or pharyngitis, or a more complex diseaseas sinusitis. Other respiratory infections can affect the lower air passages,

ing bronchitis, or the lung tissue itself, which is termed pneumonia.

THE COMMON COLDColds are easily transmitted fi'om person to personby virus-containing droplets that are released ontohands or clothing or into the atmosphere when aninfected person coughs or sneezes. Approximately200 different viruses cause colds. Antibiotics haveno effect and only symptoms can be treated; thebody's immune system must overcome infections.

SinusitisA bacterial infection may follow a viral

infection, causing pus and mucus to

accumulate in the nasal sinuses. Fever,

headache, stuff}, nose, and no sense of

smell are common symptoms.

After being carried byinfected droplets, virus

particles enter the body andinvade the cells that line thethroat and nose• These virus

particles then replicate toproduce new viruses, which

continue to multiply rapidly.

Infected nasal lining

Influenza virusTEM X 379,000

INFLUENZA]ommonly called "flu," this serious viralnfection causes fever, chills, headache,nuscle aches, cough, and pneumonia inome. It spreads rapidly, often occurringn localized outbreaks, or every few yearsn epidemics. There are three main types)fvirus: A, B, and C. Because the viruses:an change their structures, a previousmmunit7 to one type may no longer be:ffective. Influenza is life-threatening to:he very young as well as the elderly, andome epidemics kill people of all ages.

PharyngitisLaryn2itis Inflammation of the pharynx (throat)Usualb, caused by a virus, causes a sore throat, fever, difficulty

this infection can produce swallowing, and sometimes an earache

hoarseness, loss of voice, a and swollen lymph nodes in the neck.

dry cough, and sore throat.

Ton.sillitis.Most common in young children,

inflamed tonsils may cause a fever,

headache, sore throat, discomfort

when ÿwallowing, and earache. The

lymph nodes in the neck often swelh

VirusBody particles

./

The blood supply bringslymphocytes (white blood

cells) to the infected mucosa.The blood vessels within thenasal mucosa swell and cause

the secretion of excess fluid,resulting in a "runny nose."

,mphocyte

__ Blood vessel

S ome types of lymphocytemake virus-specific proteins

(antibodies) that immobilize thevirus particles, while other typessecrete chemical substances that

can destroy infected cells.

ibodies

Chemicals

Phagocytes, a type ofwhite blood cell, can

engulf and destroy deadviruses, immobilized virus

particles, and damaged

cells. Symptoms of thecold soon subside.

Ph ÿq

ACUTE BRONCHITISThis form of bronchitis - which means inflammation

of the bronchi - develops suddenly. It can occur as a

complication of an upper respiratory tract infection,such as a common cold, or can accompany measles or

influenza. This disease is usually caused by a virus, and

produces symptoms that include a sputum-producingcough, a fever, and sometimes a slight wheeze.

Site of infection

UKlally only the large and

medimn-sized bronchi are

inflamed. The glands in the

bronchiolar walls produce

abundant mucus, which is

transported upward and

coughed out. In children,

older people, and those

with lung disease, infection

may spread, inflaming the

bronchioles or lung tissue.

PNEUMONIAIn pneumonia, the smallest bronchioles and alvec

tissue become inflamed. There are two main typeLobar pneumonia affects one lobe of the lung, wbronchopneumonia affects patches of tissue in on

both lungs. Usually resulting froln a viral or bact.infection, pneumonia may also be caused by lungyeasts, or protozoa. Early symptoms include chill

fever, sweating, joint and muscle pain, and heada.Chest pain, coughing, and breathlessness develoF

BronchopneumoniaThis type of pneumonia mainly affect.

the chronically ill, the elderly, and th(

very young; it may also accompanyinfluenza or measles. The scattered

white areas shown in this illustration

are areas of inflamed lung tissue.

j, bronchus (large)

__ Secondary and tertiarybronchi (medium-sized)

NOItMAL

Inflamed _tissues _

,:::ÿ ii!i

Lumen ÿBRONCHITIS

Excess!Yll,lCHS

Effects

In acute bronchitis,

the lining or deeper

tissues of the bronchi

become inflamed and

swollen, narrowing the

lmnen. The amount of

mucus also increases

and causes congestion.

__ Bronchioles(smallest airways)

__ Infected areas

Healthy alveolÿapillaO''ÿ Irÿ k4acrÿNuurerousmacrophagcs (at)pc (ÿ]ÿ ® ÿ INkof white blood cell) areahvays ÿ N ÿ "ÿ

present inside alveoli. These cells ÿ@ ®ÿ.ÿx,4

ingest inert, inhaled irritants, but )ÿ[ÿ.. ® /ÿ--%Y'-'Qÿ)'-ÿ._ ® .

they respond slowly to bacteria..ÿ ÿ'ÿ --ÿÿÿÿ

.:'>2 ®k®,h 1® (

Neutrophils

b ,,

®ÿW4:1ÿ,®®

.ÿ.®..;.F:@F-,®® c

Infected alveoli

The infective process trigg

changes in the capillaU wa

allowing neutrophils (a ty[

white blood cell) in to figkinvading organisms. Fluid

flows in and accumulates.

PLEURAL EFFUSION ÿ,>.ÿ (Pleural inflammation may result from -'ÿ ÿ;){I \ Iinfections, particularly pneumonia or "ÿ ÿÿ,,ÿtuberculosis. It may cause excess fluid . ÿÿ\ Ito build up in the space between the ÿ ÿÿkÿ,\two membrane layers of the pleura. //ÿ ÿ('-ÿ'r.'ÿ\IIf extensive, this effusion can cause //'ÿ ÿZ, ÿ"ÿ1breathlessness. Fluid may need to be //ÿ ÿ. ", :)1removed via a hollo,,, needle or drain / ,ÿ.ÿ ÿÿ,, ',\ÿinserted through the chest wall, / fÿ ÿ:,', ::ÿ]

Lung 7' ÿ ÿ!:7> ÿf¢)ÿ;.-77::"::.:'-'{::':.:'.)ÿ .

O,.te; ,,,e,.,br:.< of€e,,,'<, 7'(t <.,,>-" t

,EGIONNAIREÿS DISEASEThis rare bacterial condition was first described in1976, after an outbreak of severe pneumonia thataffected war veterans attending an kanerican Legitconvention. The disease affects men more often tbwomen. Symptoms include a high fever, chills, muaches, a severe headache, abdominal pain, confusi(and diarrhea. Patients usually require hospitalizati,and intravenous antibiotics such as erythromycin.

The causeThe bacterium Legionella

pnemnophila is found insmall numbers in almost all

water supplies. It thrives,

however, in water-cooled

air conditioning systems,

and in plumbing systemswhere xvnl-ev qtnÿnnÿeq

DISORDERS THAT CAUSE BREATHING PROBLEMS may be present from birth ormay develop over many years. Others may occur suddenly without warning orafter an injury. Inhaled substances, such as gases, fumes, organic chemicals,

or mineral dust, can contribute to some disorders, while others havc no loÿowncause. Lung disorders may be grouped into those marked by inflammation thatis caused by a variety of chemicals, infections, allergies, or other autoimmunedisorders; those due to cancers and other growths; and those that are inherited.

PULMONARY HYPERTENSION PNEUMOTHORAXElevated blood pressure in the pulmonary arteries leadingto the lungs may be the result of a lung disorder, such asemphysema, or a circulatory disorder affecting the veins inthe arms and legs. Left-sided heart failure causing a backupof blood in the lungs also raises pulmonary artery pressure.

Increased Superior Blood flowpressure uena caua (blue arrows)

(gray arrou,s)

Pulmonary artery

A pneumothorax occurs when one of the

pleural membranes ruptures, which allowsair to enter the pleural space and cause thelung to collapse. Sometimes a spontaneouspneumothorax occurs, while others are the

result of an injury; breathlessness and chestpain are common symptoms. If air is notreabsorbed, it may compress the lungs andheart and must be drained by a needle ortube inserted into the pleural space.

Rig, ht

Thickenedheart muscle

.-"i5;

Narrowed//lldltletl

EARLY STAGES

!d :.::

LATER STAGES

Early and late stagesAs the condition develops, the

walls of the pulmonary artery

thicken with muscle and fibrous

tissue, This narrows the lumen,

impedes blood flow, and raises

pressure in the arteries. Blood

volume pumped from the heart

becomes progressively reduced.

SARCOIDOSISThought to be due to an extreme immuneresponse, sarcoidosis features multiple areasof inflammation interspersed with fibrousand grainlike tissue. The circular nodules,called granulomas (shown right), are often'found in the lungs, lymph nodes, and eyes.Symptoms include breathlessness, fatigue,joint pain, and sometimes a skin rash.

LNI

hzferiorpella

capa

Left 1.rigLung pulled out Pleural membranes

Chest wall \pulled in

Normal lungsDuring normal breathing, the lungs inflate and

are pulled out while the chest wall is pulled in.

Within the pleural space a balance is maintained

betÿveen these opposing pressures.

Chest wallpulled out

Entry

Rupture

site

collapsesinward

PneumothoraxIf air enters the pleural space, it changes the

pressure balance. This pressure change causes

the lungs to collapse inward suddenly.

FXBROSÿNG ALVEOLITISFibrosing alveolitis is sometimes called idiopathic pulmonaU,fibrosis (IPF), an autoimrnune disorder of unknown cause.It also occurs with various other immune disorders, such asrheumatoid arthritis. The disease causes fibrosis (scarring)and thickening of the walls of the lung's air sacs, resultingin severe breathlessness. Corticosteroid drugs may be given.

Inflam m ator1,substances

@

Alveoli __

Early stagesIPF may be the result

of an increased number

of white blood cells in

the alveoli of the lungs•

As these white blood

cells break down, the),

secrete substances that

cause inflammation.

@

6

Fibrous ___cells tissue Fibroblast

Late stages

Formation of scar tissue (fibrosis) occurs,

thereby destroying the alveolar walls. The

remaining alveoli both widen and thicken,

reducing the surface area for gas exchange.

Scar tissue also restricts lung expansion.

Blood vessels

D

@

(:.® Growth of fibrous tissue

The inflan:matory substances stimulate

fibroblasts to produce an overgrowth of

fibrous tissue• Thick cuboidal cells replace

, the thin cells that usually line the bronchi,

@ / restricting the passage of oxygen.

[{ ..!

VVidened Destroyedalveolus alveolar walls

Flexiblebronchoscope

Lar};

Trachea

BRONCHOSCOPYTo diagnose and sometimes to treat alung disorder, bronchoscopy may beperformed. A bronchoscope may be arigid tube or a flexible fiberoptic tube,which can reach farther into small airpassages. After a light sedative and alocal anesthetic have been given, the

tube is inserted into the patient'sthroat and .down into the bronchi.Attachments can then be passedthrough the tube to remove tissuesamples or to perform surgery.

ronchi

DUST DISEASESAsbestosis, silicosis, and pncumoconi,are some of the diseases that are caus,inhalation of dust particles. These Jut-

particles inflame lung tissue, thus cauirreversible scarring. Those most at riare people whose work exposes themthese dusts for several ):ears. Some m,

that dex:elop in hay, grain, or straw mcause farmer's lung, an allergic reactithat results in inflammation of the al:

LM \ 2S

Coal-miner's

pneumoconiosisIf coal dust is inhaled

period ofl0 to 15 yecan lead to pneumoo

or "black lung diseas,

dust particles deposit

lung tissue (left) pro(

inflammatory nodule

tissue formation dest

alveoli and bronchiol

SILICOSISSilicosis is the world's most common occupadisease. It is a for::: of fibrosis in the lungs c;by silica dust, usually in the for::: of quartz.workers, stone masons, coal miners, and'oth

at risk. Symptoms such as breathlessness ma3develop for many years. The disease may leaclung cancer, especially if an affected person s

i nhaled silica particlesare deposited in thelungs and ingested byscavenging white bloodcells called macrophages.

Silica particles

Burst cell Chemicals

Fibrous tissue

Macroj

2 Macrophages kand die, releasi

silica and chemicalslatter attract fibrobwhich produce fibrtissue. Silica is con,,

by more macrophalthe process is repea

Fibroblasts

Dense noduleof scar tissue

More fibrous tissue

develops, leadingto dense nodules of scartissue. Buildup of thistissue severely restrictseffective lung function.

)MMON IN SMOKERS AND IN URBAN OR INDUSTRIALIZED AREASÿ chronic lung:orders that obstruct the airways and reduce airflow have increased in every:t of the world. The disorders increasingly affect women, partly due to the:ater numbers who smoke or who are in industrial workplaces. Known risk

:tots include passive exposure to cigarette smoke and repeated respiratory:ections during childhood, as well as a family member with a similar disease.

the past 20 years, the number of childhood asthma cases has doubled.

IRONIC BRONCHITIS:hough recurring acute bronchitis caused by a virus or a:terium may cause chronic inflammation of the bronchi,: most common cause is smoking and chemical irritants.

first the resulting cough is troublesome mostly during: damp, cold months, but eventually it persists all year.nptoms such as hoarseness and breathlessness also occur.

EMPHYSEMA

3W BRONCHITIS DEVELOPSronchi are irritated by smoking or prolonged,osure to pollutants, they begin to produce, much mucus. This causes a progressivelyrsening cough in order to clear the airways.

Cilia MHcoI,IS

gland

IIÿIcO IIS

Healthy bronchiIn normal lungs, the airways arc lined with

cilia (surface hairs). The cilia propel mucus,

produced by mucous glands and containing

inhaled dust and germs, up into the throat,

where it is either coughed up or swallowed.

Goblet cell_

The lungs are filled with millions of tinyair sacs called alveoli. In emphysema, theybecome overstretched and rupture. Mostpeople who are severely affected are heaw,long-term smokers, but a rare inherited

enzyme deficiency is a known risk factor.At present the disorder is incurable, butstopping smoldng slows its progression.

Normal ah, eoli

Dalrlaalveoli

Damaged air sacsSmoke or other pollutants

may stimulate chemicals that

cause alveolar walls to break

down and merge. Fewer, larger sacs reduce the

area for gas exchange, causing breathlessness.

Inhaled irritants cause gobletcells to increase in number and

mucous glands to enlarge so that

more mucus is produced. Damaged

cilia cannot propel mucus along.

Mucus retained in the airway

becomes a breeding groundfor bacteria so that inflammation

is likely to recur. Cilia are slowlydestroyed; more mucus collects.

Damaged Retained mucus Enlargedcilia __ Bacteria mucous gland

Goblet cells Cells withno cilia

DEATHS ÿFROM SMOKINGA comparison of death rates iiÿ nonsmokersand smokers from both chronic bronchitisand emphysema is shown in the graph below.

500

zO

400

O300

g

200q

i00q

SMOKERS

NONSMO I(.ERS

I I35-44 45- 54 55- 64 65-74 75-84

AGE

/

I@ u

%H IZU±\ 1ÿ LUIÿC

ASTHMAAsthma attacks involve both wheezing and breathlessness,

varying in intensity, and caused by constricted airways.Allergic asthma often develops in childhood and may beaccompanied by eczema. Asthma is conihuned by lungfunction tests, and by skin and blood tests to identifysubstances triggering these attacks. In some forms of the

disease, there is no specific n-igger and no known cause.

TREATMENT OF ASTHN

Bronchioles

Tertiary bronchi

Airways affected in asthmaThe smaller bronchi and the bronchioles

(the smallest airways) become constricted,

inflamed, and congested with mucus. As

a result, breathing becomes difficult.

Blood vessels

__ Mucus__ Relaxed smooth muscle

Normal airwayNormally, the smooth muscle in the

bronchiolar walls is relaxed, creating a

wide lmnen, or space, in the center of

the air passage. This allows air to flow

easily and steadily in order to meet the

oxygen requirements of the body.

Inflammator)ÿ substanceswiden the blood

Smooth muscle

Increased mucus__

Inflammation and swellin

During an asthma attackContracted muscle walls narrow airways.

Further narrowing is caused by increased

mucus and inflammation due to chemicals

released during an allergic response.

THE ROLE OF ALLERGENSAllergens are substances that trigger anallergic response. Common allergens thatmay trigger or intensify attacks of asthmainclude molds, pollens, animal dander,dust, and some foods and drugs. Amxiety,vigorous exercise in cold weather, andrespiratory infections are other factors.

A specific allergenIn SOlne people, exposure to certain pollens

triggers asthma attacks. A variety of pollen

Obstruction of airways may be relieveinhaled sterbids to suppress inflammaand by bronchodilator drugs, which rbronchiolar wails. Beta adrenergic rec

stimulants and anticholinergic drugsalso used for the relief of asthma attacBoth the frequency and severity of all,asthma attacks can be reducedby avoi

the specific allergens that trigger atta(

]VIAST- CELL STABILIZERS

Mast cells play a critical role in the allergicresponse. Allergens (antigens) attach to thesecells, stimulating them to produce histamine.Mast-cell stabilizers can inhibit the productiorof histamine by bronchiolar mast cells, whichhelps reduce inflammation of the airways.

Histamine Mast cells l, Vall of brot

ADru6°irumy ÿÿBEFO1LE DRUG AFTER D!I_U,

BRONCHODILATORS AND STEROIDSBronchodilator drugs work by affecting thenerve signals that control the contractionand relaxation of bronchiolar muscles. Theydo not reduce inflammation of the mucouslining. Corticosteroid drugs, usually inhaled,widen bronchioles by reducing inflammation•

Improved airThe constricted airway

widens, thus allowing dir

to flow more easily.

M51cous liningCorticosteroids reduce

inflammation of this

layer to ease breathing.

Respiratorybronchiole

lueoliAs air flow i

alveoli incre

breathlessne

relieved. Sm

air flow is. es

LUNG @ANCER['HE MOST COMMON CAUSE OF LUNG CANCER- about 87 percent of all cases in

ne US - is tobacco smoldng. In the past, lung cancer was far more common in

hen than women because more men than women smoked in the first half of this

:entury; now its incidence in women is rapidly rising and it has overtaken breast:ancer as the most common cancer causing deada in women. Other causes of

ung cancer include exposure to coal dust, asbestos, and silica. Lung cancer is

nore common in industrial areas of the world than in rural areas.

CAUSES OF LUNG CANCERMany inhaled irritants trigger the growthf abnormal cells in the lungs. Cigarette

smoke, however, contains thousands ofknown carcinogenic (cancer-causing)

substances, and is the main cause oftung cancer. Diagnostic tests

include a chest X-ray, biopsy, and

bronchoscopy (examining thebronchi through a viewing tube).

HOW SMOICING DAMAGES THE LUNGSTobacco smoke is a complex mixture of over 3,000different substances, and burning cigarette tar isstrongly carcinogenic. Some risk factors known topredispose towaxd the development of lung cancerinclude the number of cigarettes smoked per day,their tar content, the number of years a person hassmoked, and the depth of inhalation.

CapillarlResph'ator1,airway

Spreading carcinogensEach lung contains millions of air spaces.

Carcinogenic substances from tobacco

smoke, notably tar, are able to pass from

these directly into the bloodstream.

Carcinogens

Goblet cell

d7

2:1 0...'.f/

Basementmembraue cells

Squamous cells I

Over a number of years,

columnar cells damaged

by smoke flatten and turninto squamous cells, which

gradually lose their cilia.

Cilia Columnar cell

0oo 0,)0oÿ ÿ Columnar cellstopped_ÿ_ by cilia (tiny hairs) linehealthy bronchi. Under thislayer are basal cells, which

"ÿ"Tÿ constantly divide to replace

l ?-"ÿ ÿ: ] damaged columnar cells.I<ZzzE2q Mucus produced by goblet

:'ÿ ] cells lubricates the bronchi.

I Basal

........ ::.ÿ .v•.=m::- ÿL ÿ "" • ....... T ..... ÿ -"

..-!.,-ÿ ÿ...ÿ.... ©...

-7 : @ .-

Tumor in an alveolusA tiny tumor fills a single alveolus. A

few of the cancer cells (shown in red)

have broken away and begun to spread.

GROWTH OF LUNG CANCERIn about 95 percent of lung cancercases, the tumor starts to grow in

the bronchi, where it may enlarge orbleed and obstruct breathing. Somecells of a bronchial tumor may breakaway and infiltrate other parts of thelung, or spread to other organs eitherdirectly or via the bloodstream. Thecancerous tissue that develops at thenew site is known as a metastasis.

SEM x 230

Basal cellsbecome cancerous

o

In an attempt to replace

the damaged squamous

cells, the basal ceils change.... -<=ÿÿ and multiply at an increased

>ÿ <5 ] rate (dysplasia);some of-<=>-.ÿ-::' " ÿ these become cancer cells.

Multiplyin2 cancercells break through_

The cancer cells start to

replace healthy cells. Ifthese cells break through thebasement membrane, they

can metastasize, establishing

new sites of cancer.

7 -.

v_ÿ ÿ J-V£ 3!- 3L vk_* ±vi v.ÿ

A persistent cough is usually the earliest symptom oflung cancer. Because most people who develop lungcancer are smokers, this is often dismissed as simplya "smoker's cough." Other symptoms of lung cancer

include coughing up blood, wheezing, persistenthoarseness, headache, weight loss, and chest pain.

Blood Growth2vessels prim ark,

tl, llllOl"

Symptoms fromtumor growthA tumor that grows may

obstruct a bronchus, causing

shortness of breath and chest

pain. Sometimes a tumor

invades the esophagus, thus

making swallowing difficult.

LOBECTOMYIf diagnostic tests confirm the presence of lung cancer,

a lobectomy, or the removal of a lobe of the lung, maybe performed. This operation is only appropriate incertain circumstances. The tumor must be small and

confined to a localized area; breakaway cancer cellsmust not have spread to other parts of the body; andthe patient must also be reasonably well. For the fewfor whom the operation is suitable, it offers relief ofsymptoms as well as the chance of a cure.

Symptoms ofspreading cancerLung cancer metastasizes (or

spreads) to other parts of the

body and causes a variety of

symptoms. Metastases in bones

may cause pain and fractures;

in the brain they may cause

paralysis and cont\ÿsion; in/ÿ

the liver they may cause //i inausea and weight loss. [ 1\./I I::/

Bone metastasis

j(Liver metastasis

-i,

Brain metastasis

riHlar)z tl,llllOl"

/ nodej) i,\\ . Lr,,pl,

I metastasis?) Adrenal"ÿ ÿt gland

( metastasis

Spindlefibers

Duplicatedchl'o Ill O S 0111 e

Threadlikechl*o IH os o tli es

Mkylating drugsSpindle fibers form in cells that are

about to divide. By brealdng up these

fibers, Mkylating drugs interfere with

rapidly reproducing cancer cells.

Cytotoxic antibioticsFor cells to multiply, DNA must replicate

to create chromosomes in the new ceil.

Cytotoxic antibiotics prevent

replication, halting growthof normal and cancer cells.

DRUG TREATMENTSome anticancer drugs will relieve symptoms of certainlung cancers, or cause those symptoms to temporarilydisappear. Since these drugs damage normal cells aswell, they are given at intervals of 3 to 4 weeks toallow healthy tissue to recover between treatments.Vomiting, diarrhea, and hair loss may be side effects.

The diseased lobe ismoved to one side so

that the vessels and lymphnodes can be easily seen.

Lymph node samples areobtained. These specimens

are examined immediatelyunder a microscope to find

out whether the cancer has

spread to the nodes.

Ll, mph nodes

L I I

I ffer administration ofa general anesthetic, the

surgeon makes an incision

around the side of the chest.The muscles between the ribs

are cut and the ribs are then

separated in order to expose

the affected lung, which iscovered by its pleura.

RibsDiseased lobe

] , t

Blood vessels

Diseased lobeStump of bronchus

Cut arteries

Cut vein

Health), lung tissue

The arteries, veins, andmain bronchus that supply

the affected lobe are first tiedoff and then cut. The remaining

bronchial stump is permanentlyclosed off with sutures to stopany air fiom leaking into thechest cavity, and the diseased

lobe is cut away and removed.

Two chest drains areinserted into the chest

cavity before it is closed.

The drains, which removeexcess blood and fluid fromthe area around the lungs,are left in place for 3 to Sdays and then removed.

Chest drains Closed incision