2. The Respiratory System

3. Components The Nasal passages The tubes of respiration The Trachea The Bronchi and Bronchioles The Alveoli The Lungs

5. Basic Facts Pulmonary Ventilation - Correct term for breathing. Average volume = 4 to 6 Litres, weighs approx 1 kg Surface Area = 60-80 m 2 Main muscles – Diaphragm & Inter-costal muscles Pleura help the lungs to expand contract freely Visceral Pleura – membrane around lungs Parietal Pleura – membrane lines thoracic cavity. Pleural fluid – lubricates above.

6. Gaseous Exchange This occurs in the alveoli. Oxygen In – Carbondioxide Out Diffusion takes less than 1 second Across semi-permeable membrane

7. Effect of Gaseous Exchange on Air Composition… GasAir InAir Out Oxygen21%16% Carbon Dioxide 0.04%4% Nitrogen78%

8. Lung Capacities Tidal Volume (TV 500ml) Volume when breathing normally – increases during exercise Residual Volume (RV 1200ml) Remains after full expiration Vital Capacity (VC 500ml) Volume expired after maximum inspiration Forced Expiratory Volume (FEV1) Volume forcibly expired in first second (80%)

9. Lung Capacities Inspiratory Reserve Volume (IRV 3000ml) Maximum volume of air after full inspiration Expiratory Reserve Volume (ERV 1200ml) Maximum volume of air exhaled after full inspiration Total Lung Capacity (VC 6000ml) Sum of all Lung Volumes Minute Ventilation (VE 7500ml) Volume breathed in & out per minute

10. Governing Factors Size of Lungs/Ribcage – generally genetic Strength of respiratory muscles Resistance to air flow as a consequence of: Colds Lung disorders Smoking