1. Function, Types of Respiration

2. Respiration External Respiration: exchange of gases between air in the lungs and in the blood Internal Respiration: exchange of gases between the blood and the cells of the body Cellular Respiration: use of oxygen by cells to produce ATP

3. Transport of Gases (Review) O 2 + Hemoglobin = oxyhemoglobin Most CO 2 is carried as bicarbonate ion (HCO 3 -) in the blood CO 2 + H 2 O >> HCO 3 - + H+ Some CO 2 carried by RBC’s: CO 2 +hemoglobin

4. Respiration: Inspiration & Expiration Inspiration/Inhalation: moves air into the lungs. Muscles: controlled by phrenic nerve reflex arc diaphragm (top to bottom movement) external intercostals (front to back/side to side). Expiration/Exhalation: moves air out of the lungs. Muscles: diaphragm

5. Mechanics of Breathing: Inhalation Diaphragm contracts/ flattens, moving downward This ↑ the VOLUME in the thoracic cavity and ↓ the PRESSURE. The pressure is now greater outside of the thoracic cavity and air flows INTO the lungs. External intercostals contract – lifts ribcage up

6. Mechanics of Breathing: Exhalation Diaphragm relaxes, moving ↑ External intercostals relax This ↓ the VOLUME in the thoracic cavity and ↑ the PRESSURE The pressure is now greater inside the thoracic cavity and Air flows OUT of lungs.

7. Forced Expiration Muscles for forceful expiration: internal intercostals—depress the ribcages, (↓ the front-to-back size of the thorax) abdominal muscles—push the abdominal organs against the underside of the diaphragm, elevating it further

8. Regulation of Breathing Respiratory control center: Brainstem: medulla & pons control rate/depth of breathing. Cerebral cortex can override brainstem control (as in blowing up a balloon)

9. Regulation of Breathing

10. Spirometer: device used to measure the amount of air exchanged in breathing. Tidal Volume (TV): amount of air breathed in and out with each breath (500ml) Vital Capacity (VC): largest amount of air that can be moved in and out of the lungs in one inspiration and expiration Expiratory Reserve Volume (ERV): the amount of air that can be forcibly exhaled after expiring the tidal volume Inspiratory Reserve Volume (IRV): the amount of air that can be forcibly inspired over and above a normal respiration VC = TV + IRV + ERV Residual Volume (RV): the air that remains in the lungs after the most forceful expiration Total Lung Capacity (TLC): total amount of air found in the lungs. TLC=VC+RV