1. Respiratory Physiology
Exercise 40
Respiratory Physiology

2. Processes of respiration
Pulmonary ventilation
External respiration
Transport of respiratory gases
Internal respiration or cellular respiration

3. Mechanisms of respiration
Pulmonary ventilation
Inspiration
Expiration
Respiratory muscles
Diaphragm
External intercostal
Others

4. Mechanisms of respiration
Steps of ventilation
Contraction of diaphragm and external intercostal muscles
Increase of thoracic volume
Expansion of the pleural cavities and lungs
Decrease of lung pressure below atmospheric pressure

5. Mechanisms of respiration
Inspiration
Lung pressure becomes equal to atmospheric pressure
Air stops to flow inside
Relaxation of respiratory muscles
Recoiling of the lung tissue

6. Mechanisms of respiration
Decrease of intrathoracic and intrapulmonary volumes
Increase of pulmonary pressure
Expiration

7. Mechanisms of respiration
Pneumothorax it is the entry of air into the pleural cavity
It breaks the fluid bond between the visceral and parietal pleura
It will cause the lung to collapse – atelectasis

8. Respiratory volumes and capacities
Spirometry
Tidal volume (TV)
It is the amount of air inspired or expired with each breath under resting conditions
500 ml

9. Respiratory volumes and capacities
Inspiratory reserve volume (IRV)
It is the amount of air that can be forcefully inspired after a normal tidal inspiration
3100 ml

10. Respiratory volumes and capacities
Expiratory reserve volume (ERV)
It is the amount of air that can be forcefully expired after a normal tidal expiration
1200 ml
It is reduced in conditions in which the elasticity of the lungs is decreased

11. Respiratory volumes and capacities
Vital capacity (VC)
It is the maximum amount of air that can be expired after a maximal inspiration
4800 ml
VC = TV + IRV + ERV

12. Respiratory volumes and capacities
Residual volume (RV)
It is the amount of air that remains in the lung after a ERV
1200 ml

13. Respiratory volumes and capacities
Functional residual capacity (FRC)
It is the amount of air that remains in the lung after a quiet respiratory cycle
2400 ml
FRC = ERV+RV

14. Respiratory volumes and capacities
Total lung capacity (TLC)
It is the total volume of the lungs
6000 ml
TLC = VC+RV

15. Respiratory volumes and capacities

16. Respiratory volumes and capacities
Nonrecording spirometer
Handheld dry spirometer
Measures only expired air
Wet spirometer
Recording spirometer
Measures inspired and expired air

17. Pulmonary disorders Obstructive Bronchitis Asthma Restrictive
Tuberculosis
Poliomyelitis

18. Respiratory volumes and capacities
Forced vital capacity (FVC)
It is the amount of air expired after a deep inspiration and a forced and quick expiration
Reduced in restrictive pulmonary diseases

19. Respiratory volumes and capacities
Forced expiratory volume measurement (FEV1%)
It is the percentage of vital capacity that is exhaled during specific intervals of time
It is reduced in obstructive diseases

20. Respiratory rate and depth
Factors that changes the RR
Exercise
Coughing
Walking
Talking
Laughing, etc

21. Respiratory sounds Bronchial sounds Heard below the larynx
Vesicular sounds
Air filling the alveolar sacs
Heard over the chest
Crepitation (crackles)
Wheezing – a whistling sound
Crepitation or crackles: bubbling sound audible with inspiration due to air movement through alveolar fluid as in pneumonia and other lung diseases

22. Role of respiratory system in acid-base balance of blood
Blood pH
Carbonic acid-bicarbonate buffer
The main body buffer

23. Acid-base imbalance Alkalosis Blood pH above 7.45
Respiratory or metabolic
Acidosis
Blood pH bellow 7.35