1. Respiratory System Physiology

2. Inspiration - air flowing in Caused by a contraction of diaphragm and external intercostal muscles Lungs adhere to the thorax walls because of the surface tension between the plural membranes Expiration - air flowing out Caused by the normal elasticity of the lungs and the collapse of the ribcage Can be affected by conditions such as asthma or bronchitis

3. Respiratory Volumes and Capacity –Tidal Volume - Normal breathing (around 500 ml of air) –Inspiratory Reserve Volume - Maximum volume that can be inhaled over the TV –Expiratory Reserve Volume - Maximum volume that can be exhaled after the TV –Vital Capacity - Total amount of exchangable air (around 4800 ml)

4. Gas Exchange Powered by diffusion - Movement from a high to low concentration More O 2 in alveoli, more CO 2 in body cells O 2 attaches to hemoglobin Most CO 2 is carried by bicarbonate ions found in the plasma

6. Neural Regulation of Respiration Neural centers that control rate and depth are located in the medulla The pons appears to smooth out respiratory rate Normal respiratory rate (eupnea) is 12–15 respirations per minute Hypernia is increased respiratory rate often due to extra oxygen needs

8. Factors Influencing Respiratory Rate and Depth Physical factors Increased body temperature Exercise Talking Coughing Volition (conscious control) Emotional factors

9. Factors Influencing Respiratory Rate and Depth Chemical factors Carbon dioxide levels Level of carbon dioxide in the blood is the main regulatory chemical for respiration Increased carbon dioxide increases respiration Changes in carbon dioxide act directly on the medulla oblongata

10. Respiratory Problems Atelectasis – Collapsed lung occurs when air is allowed to enter the pleural space and the lung collapses Hypoxia - not enough O 2 CO poisoning – CO can permanently bind to hemoglobin

11. Chronic Obstructive Pulmonary Disease (COPD)

12. Other items Blood doping – Increases RBC count Homologous and Autologous Erythropoietin – brings RBC count up Polycythemia – Too many RBC’s

13. Developmental Aspects of the Respiratory System Lungs are filled with fluid in the fetus Lungs are not fully inflated with air until two weeks after birth Surfactant that lowers alveolar surface tension is not present until late in fetal development and may not be present in premature babies

14. Aging Effects Elasticity of lungs decreases Vital capacity decreases Blood oxygen levels decrease Stimulating effects of carbon dioxide decreases More risks of respiratory tract infection

15. 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 somewhat with old age