1. Chapter 13 – Part 3 The Respiratory System

2. Lung 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

4. Lung 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

5. Lung 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

6. Secondhand 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

7. 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

8. 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

9. 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

10. 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

11. Treatment of Lung Cancer  However, the treatment in most cases is: Radiation therapy and chemotherapy  Is usually the only option

12. 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)

13. Don’t Smoke!  When smoking is begun during the early teens, the lungs never completely mature, and those additional alveoli are lost forever.

14. Respiratory Disorders: Chronic Obstructive Pulmonary Diseases (COPD)  Exemplified by chronic bronchitis and emphysema  Major cause of death and disability in the United States

15. Respiratory Disorders: Chronic Obstructive Pulmonary Diseases (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

16. Respiratory Disorders: Chronic Obstructive Pulmonary Diseases (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

17. Emphysema  Alveoli enlarge as adjacent chambers break through  Chronic inflammation promotes lung fibrosis  Lungs become less elastic and airways collapse during expiration

18. Emphysema  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, O 2 exchange is surprisingly efficient, and cyanosis does not usually appear until late in the disease

19. Chronic 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

20. Chronic Obstructive Pulmonary Disease (COPD)

21. Developmental Aspects of the Respiratory 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

22. Developmental Aspects of the Respiratory 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

23. Infant Respiratory Distress 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

24. Infant Respiratory Distress 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

25. Sudden Infant Death syndrome (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

26. Developmental Aspects of the Respiratory 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

27. Respiratory Rate Changes Throughout 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

28. Aging 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

29. Asthma  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