Chapter 15 The Respiratory System

1. Chapter 15The Respiratory System

2. The Respiratory System • The respiratory system works with the cardiovascular system to accomplish: • The exchange of gases (O2 and CO2) between air and the blood • The exchange of gases (O2 and CO2) between blood and tissue fluid • Transport of gases to and from the lungs and the tissues

3. The Respiratory System

4. The Respiratory System - Nose • Contains two nasal cavities • Functions • Warms air during inhalation • Cleanses air-coarse hairs and mucus • Humidifies air-wet surfaces of membrane • Contain odor receptors • Tear glands drain into nasal cavity

5. The Respiratory System - Pharynx • Connects nasal and oral cavities to larynx • Three divisions • Nasopharynx • Oropharynx • Laryngopharynx • Tonsils form a protective ring • Larynx and trachea are normally open • Esophagus is normally closed

6. Respiratory System - Larynx • Passageway for air between pharynx and trachea • Vocal cords • Folds of mucosa that vibrate to make sounds • Glottis-opening between folds • Epiglottis • Prevents food from entering the respiratory tract

7. The Respiratory System - Trachea • Connects larynx with primary bronchi • Supported by C-shaped cartilage rings • Cilia sweep mucus toward the pharynx • Smoking can destroy cilia

8. Respiratory System – Bronchial Tree • Right and left primary bronchi • Resemble trachea in structure • Branch to secondary bronchi • Eventually lead to bronchioles • As airways become smaller, walls become thinner • Lack cartilage rings • Each bronchiole leads into alveoli

9. The Respiratory System - Lungs • Divided into lobes • Right lung has 3 • Left lung has 2 • Each lobe is divided into lobules • Lobule has a bronchiole serving many alveoli • Lungs are covered by serous membrane called pleura

10. The Respiratory System - Alveoli • Surrounded by blood capillaries • Gas exchange occurs the moist membranes • Oxygen diffuses into blood • Carbon dioxide diffuses into alveoli • Alveoli must stay open to receive air

11. Mechanisms of Breathing • Respiratory Volumes • Tidal volume • Amount of air moving in and out with each breath • Around 70% of this air reaches the alveoli, 30% remains in the airways • Vital capacity • Maximum volume moved in and moved out in a breath • Illness can affect vital capacity • Inspiratory reserve volume • Forced inhalation (amount of air brought in above tidal volume) • Expiratory reserve volume • Forced exhalation (air exhaled beyond tidal volume) • Residual volume • Amount of air always remaining in lungs

12. Vital Capacity

13. Mechanisms of Breathing • Understanding Ventilation • There is a continuous column of air from pharynx to alveoli • The lungs lie in the sealed-off thoracic cavity • Rib cage forms top and sides • Intercostal muscles lie between the ribs • Diaphragm forms the floor • The lungs adhere to the thoracic wall by way of the pleura

14. Expiration Inspiration

15. Mechanisms of Breathing • Control of Ventilation • Controlled by respiratory center • In medulla oblongata of brain • Inspiration • Respiratory center sends out nerve impulses to the diaphragm and external intercostals • Expiration • Respiratory center ceases to send out nerve impulses to the diaphragm and external intercostals • Input to the respiratory center • Influenced by chemical and neural input

16. Mechanisms of Breathing • Chemical Input to Respiratory Center • Directly sensitive to CO2 and H+ • When levels rise, respiratory center increases rate and depth of breathing • Indirectly responsive to O2 • Chemoreceptors in the carotid and aortic bodies • Sensitive to oxygen levels in blood • When levels decrease, impulses are sent to respiratory center • Respiratory center then increases rate and depth of breathing

17. Gas Exchanges in the Body

18. Gas Exchanges in the Body • External Respiration • Exchange of gas between air in alveoli and blood • Gases exert pressure • Partial pressure refers to the amount of pressure each gas in a mixture exerts • Symbolized by Pco2 and Po2 • Blood in pulmonary capillaries has a higher Pco2 than atmospheric air • CO2 diffuses from blood into alveoli

19. Gas Exchanges in the Body • External Respiration Continued • Most CO2 is carried as bicarbonate ions (HCO3-) • Carbonic anhydrase catalyzes the breakdown of carbonic acid (H2CO3)

20. Gas Exchanges in the Body • External Respiration Continued • Pressure gradient for oxygen is the reverse of carbon dioxide • Po2 is low in pulmonary capillaries and high in alveoli • Oxygen diffuses into blood • Hemoglobin picks up oxygen and becomes oxyhemoglobin

21. Gas Exchanges in the Body • Internal Respiration • Exchange of gas between systemic capillaries and tissues • Partial pressure of oxygen is greater in capillaries than tissues • Oxyhemoglobin gives up oxygen which diffuses out of the blood into tissues

22. Gas Exchanges in the Body • Internal Respiration • CO2 diffuses into the blood • A small amount combines with hemoglobin • Most CO2 combines with H2O • Carbonic anhydrase speeds up the reaction

23. Disorders of the Respiratory System • The Common Cold • Caused by viruses (antibiotics ineffective) • Pharyngitis • Inflammation of the throat • May be caused by Streptococcus pyogenes (Strep throat) • Severe sore throat, high fever, white patches in throat region • Tonsillitis • Tonsils (lymphoid tissue) become inflamed and enlarged • Laryngitis • Inflammation of the larynx • Causes hoarseness • Persistent laryngitis is one warning sign of cancer

24. Disorders of the Respiratory System • Sinusitis • Infection of the cranial sinuses • Nasal congestion blocks sinus openings • Symptoms include postnasal discharge, headache, and facial pain • Otis Media • Inflammation of the middle ear • Nasal infections spread to the ear by way of the auditory tubes • Antibiotics are usually an effective treatment • Choking • Obstruction of the trachea • Heimlich maneuver may expel blockage • A tracheostomy is the insertion of a breathing tube into the trachea • Symptoms include postnasal discharge, headache, and facial pain

25. Disorders of the Respiratory System • Acute bronchitis • Infection of the primary and secondary bronchi • Usually it is preceded by a viral infection that leads to a secondary bacterial infection • Chronic bronchitis • Airways are inflamed and filled with mucus • Bronchi have undergone degenerative change including the loss of cilia • Smoking is the most common cause • Asthma • A disease of the bronchi and bronchioles

26. Disorders of the Respiratory System • Pneumonia • Viral or bacterial infection • Bronchi or alveoli fill with fluid • High fever, chest pain and headache • Pulmonary tuberculosis • Caused by the bacterium Mycobacterium tuberculosis • Cells build a protective capsule (tubercle) around the bacteria

27. Disorders of the Respiratory System • Emphysema • Damage to the walls of the alveoli • A chronic and incurable disease • Smoking is the major cause of this disease • Cystic fibrosis (CF) • Genetic in origin (recessive) • Mucus in the lungs becomes very thick and sticky • Pulmonary fibrosis • Fibrous connective tissue builds up in the lungs causing a lack of elasticity • This reduces vital capacity

28. Common Bronchiole and Pulmonary Diseases

29. Disorders of the Respiratory System • Lung Cancer • A series of progressive steps • Thickening and callusing of mucosa of bronchi • Loss of cilia • Cancerous changes occur in callus cells • Tumors may obstruct bronchi • Cancerous cells spread to other parts of the body • Lung cancer can be caused by secondhand smoke