1. The Respiratory System II Physiology

2. The major function of the respiratory system is to supply the body with oxygen and to dispose of carbon dioxide Events happening during respiration: 1.Pulmonary ventilation: Air must move into and out of the lungs; this process is commonly known as breathing 2.External respiration: Gas exchange between the pulmonary blood and alveoli must take place

3. Physiology 3.Respiratory gas transport: Oxygen and carbon dioxide must be transported to and from the lungs and tissue via the blood stream 4.Internal respiration: Gas exchange between the blood and tissue cells

4. Mechanics of Breathing Volume changes leads to pressure change, which leads to the flow of gases to equalize the pressure Inspiration: air is flowing into the lungs Expiration: air is leaving the lungs Inspiratory muscles: diaphragm and external intercostals

5. Inspiration At the end of a normal inspiration: -Chest is expanded -Rib cage is elevated -Diaphragm is depressed and flattened

6. Expiration At the end of a normal expiration: -Chest is depressed -Rib cage is descended -Diaphragm is elevated and dome- shaped

7. Forced expiration Forced expiration: the internal intercostal muscles are activated to help depress the rib cage, and the abdominal muscles contract -Asthma: the respiratory passageways are narrowed by spasms of the bronchioles -Pneumonia: the respiration passageways are clogged with fluid or mucus

8. Respiratory Volumes and Capacities Tidal volume (TV): the amount of air into and out of the lungs when breathing normally and quietly (approximately 500 ml of air) Inspiratory reserve volume (IRV): the amount of air that can be taken in forcibly over the tidal volume (approximately 2100- 3200 ml of air)

9. Respiratory Volumes and Capacities Expiratory reserve volume (ERV): The amount of air can be forcibly exhaled after a tidal expiration (approximately 1200 ml) Residual volume (RV): Even after the most strenuous expiration, about 1200 ml of air still remains in the lungs, and it can not be voluntarily expelled Vital Capacity (VC): the total amount of exchangeable air ( TV+IRV+EVR)

10. Dead Space Volume The amount of air remains in the conducting zone passageways and never reaches the alveoli

11. Respiratory Sounds Bronchial sounds: are produced by air rushing through the large respiratory passageways Vesicular sounds: occurs as air fills the alveoli

12. Respiration External Respiration: It is the actual exchange of gases between the alveoli and the blood Gas exchanges in the body occur according to the laws of diffusion Internal Respiration: It is the exchange of gases that takes place between the blood and the tissue cells

13. Oxygen Transport in the Blood Oxygen is transported in the blood in two ways: -Most attaches to hemoglobin molecules inside the red blood cells to form oxyhemoglobin -A very small amount of oxygen is carried dissolved in the plasma

14. Carbon Dioxide Transport in the Blood Most carbon dioxide is transported in plasma as the bicarbonate ion (HCO 3 - ) A smaller amount (between 20%-30%) is carried inside the red blood cells bound to hemoglobin -Carbon dioxide attaches to hemoglobin at a different site than oxygen does, so it does not interfere in any way with oxygen transport

15. Before carbon dioxide can diffuse out of the blood into the alveoli, it must: -Combine with hydrogen ions (H + ) to form carbonic acid (H 2 CO 3 ) -carbonic acid (H 2 CO 3 ) quickly splits to form water and carbon dioxide -Carbon dioxide then diffuses from the blood and enters the alveoli -HCO 3 - + H +  H 2 CO 3  CO 2 + H 2 O Carbon Dioxide Transport in the Blood