Chapter 13 – Part 3The Respiratory System

Lung CancerLung Cancer

Accounts for 1/3 of all cancer deaths Most types are tremendously aggressive

and metastasize rapidly and widely Because most cases cannot be

diagnosed until they are advanced, it has a notoriously low survival rate: The overall 5-year survival rate = 7%

The average person survives only about 9 months after diagnoses

Lung Cancer and SmokingLung Cancer and Smoking

Over 90% of lung cancer patients are smokers

Smoking gives people bad breath, yellow teeth, wrinkles their skin, and leaves an unpleasant residue on clothes and hair

Lung Cancer and SmokingLung Cancer and Smoking

The affects of smoking a single cigarette:

Increased heart rate, constricts peripheral blood vessels, disrupts the flow of air in the lungs, and affects one’s brain and mood

The affects of long-term smoking:

Contributes to athersclerosis and heart disease, strokes, cataracts, and early onset of osteoporosis

Secondhand SmokeSecondhand Smoke

Each year secondhand tobacco smoke causes 3000 lung-cancer deaths among nonsmokers in the US.

It also appears to be linked to heart disease

People who work in bars and restaurants are especially vulnerable

Effects of Smoking Effects of Smoking

Ordinarily sticky mucus and cilia do a fine job of protecting your lungs from irritants

Smoking overwhelms these cleaning devices and they eventually become nonfunctional

Effects of Smoking Effects of Smoking

Continuous irritation causes the following:

1. Prompts the production of more mucus

2. Slows the movements of cilia that clear this mucus

3. Depresses the activity of lung macrophages

Effects of Smoking (continued) Effects of Smoking (continued)

4. Mucus pools in the lower respiratory tree

5. Increased frequency of pulmonary infections (including pneumonia and COPD)

6. Free radicals and other carcinogens in tobacco that ultimately result in lung cancer

Treatment of Lung Cancer Treatment of Lung Cancer

Most effective treatment:Complete removal of the diseased lung in an attempt to halt metastasis

Usually not an option because:

Metastasis has usually occurred by the time of diagnosis

The patient’s chance of survival are too poor to justify the surgery

Treatment of Lung Cancer Treatment of Lung Cancer

However, the treatment in most cases is: Radiation therapy and chemotherapy

Is usually the only option

Quit Smoking!Quit Smoking!

The incidence of lung cancer is 20 to 1 for smokers versus nonsmokers.

This ratio drops to 2 to 1 for ex-smokers who have not smoked in in 15 years.

Using treatments such as nicotine patches, nasal sprays, and inhalants has been shown to double the success rate of quitting smoking (from 10 to 20 percent)

Don’t Smoke!Don’t Smoke!

When smoking is begun during the early teens, the lungs never completely mature, and those additional alveoli are lost forever.

Respiratory Disorders: Chronic Respiratory Disorders: Chronic Obstructive Pulmonary Diseases Obstructive Pulmonary Diseases (COPD)(COPD)

Exemplified by chronic bronchitis and emphysema

Major cause of death and disability in the United States

Respiratory Disorders: Chronic Respiratory Disorders: Chronic Obstructive Pulmonary Diseases Obstructive Pulmonary Diseases (COPD)(COPD) Features of these diseases

1. Patients almost always have a history of smoking

2. Labored breathing (dyspnea) becomes progressively more severe

3. Coughing and frequent pulmonary infections are common

Respiratory Disorders: Chronic Respiratory Disorders: Chronic Obstructive Pulmonary Diseases Obstructive Pulmonary Diseases (COPD)(COPD)

Features of these diseases (continued)

4. Most victims retain carbon dioxide, are hypoxic and have respiratory acidosis

5. Those infected will ultimately develop respiratory failure

EmphysemaEmphysema Alveoli enlarge as adjacent chambers break

through

Chronic inflammation promotes lung fibrosis

Lungs become less elastic and airways collapse during expiration

EmphysemaEmphysema

Patients use a large amount of energy to exhale and are always exhausted

Overinflation of the lungs leads to a permanently expanded barrel chest

Because air is retained in the lungs, O2 exchange is surprisingly efficient, and cyanosis does not usually appear until late in the disease

Chronic BronchitisChronic Bronchitis

Mucosa of the lower respiratory passages becomes severely inflamed

Mucus production increases

Pooled mucus impairs ventilation and gas exchange

Risk of lung infection (such as pneumonia) increases

Hypoxia and cyanosis are common

Chronic Obstructive Pulmonary Disease Chronic Obstructive Pulmonary Disease (COPD)(COPD)

Developmental Aspects of the Developmental Aspects of the Respiratory SystemRespiratory System

Lungs are filled with fluid in the fetus

At birth the fluid-filled pathway is drained

Lungs are not fully inflated with air until two weeks after birth

The success of this change – that is, from nonfunctional to functional respiration – depends on the presence of surfactant

Developmental Aspects of the Developmental Aspects of the Respiratory SystemRespiratory System

Surfactant lowers the surface tension of the film of water lining each alveolar sac so that the alveoli do not collapse between each breath

Is not present in large enough amounts until late in fetal development

May not be present in premature babies

Infant Respiratory Distress Infant Respiratory Distress Syndrome (IRDS)Syndrome (IRDS)

Occurs in infants born prematurely or those in which surfactant production is inadequate for other reasons

These infants have dyspnea within a few hours after birth

Use tremendous amounts of energy just to keep re-inflating their alveoli, which collapse after each breath

Infant Respiratory Distress Infant Respiratory Distress Syndrome (IRDS)Syndrome (IRDS)

Although IRDS still accounts for over 20,000 newborn deaths a year, many of these babies survive because of current treatments

Treatment: Use of equipment that supplies a positive pressure continuously

Keeps the alveoli open and working in gas exchange until adequate amounts of surfactant are produced by the maturing lungs

Sudden Infant Death syndrome Sudden Infant Death syndrome (SIDS)(SIDS)

Apparently healthy infant stops breathing and dies during sleep

Some cases are thought to be a problem of the neural respiratory control center

One third of cases appear to be due to heart rhythm abnormalities

Developmental Aspects of the Developmental Aspects of the Respiratory SystemRespiratory System

Important birth defects: 1. Cystic fibrosis – Causes

oversecretion of thick mucus that clogs the respiratory system

• Most common lethal genetic disease in the US

• Strikes 1 out of every 2400 children; Every day two children die of it

2. Cleft palate

Respiratory Rate Changes Respiratory Rate Changes Throughout LifeThroughout Life Newborns – 40 to 80 respirations per

minute

Infants – 30 respirations per minute

Age 5 – 25 respirations per minute

Adults – 12 to 18 respirations per minute

Rate often increases again in old age

Aging EffectsAging Effects Chest wall becomes more rigid and the

lungs begin to lose their elasticity

Vital capacity decreases by about 1/3 by the age of 70

Blood oxygen levels decrease

Sensitivity to the stimulating effects of carbon dioxide decreases

More risks of respiratory tract infection Ciliary activity of the mucosa decrease and

the phagocytes become sluggish

AsthmaAsthma

Asthma - Chronically inflamed hyper- sensitive bronchiole passages

The bronchioles respond to irritants with dyspnea, coughing, and wheezing

Some irritants include: dust mites, cockroach droppings, dog dander, and fungi