Respiratory Physiology – Summary of Knowledge

Respiratory Physiology – Summary of Knowledge

1. Normal Inhalation:

• Alveolar pressure is lower than atmospheric pressure.

• The parietal pleura and visceral pleura separate as the lung expands.

• The diaphragm contracts, raising the rib cage, creating negative pressure in the pleural cavity, helping the lungs expand.

2. Respiratory Air Volumes:

• Tidal Volume: The amount of air exchanged during each normal breath.

• Vital Capacity: The maximum amount of air that can be inhaled after exhaling completely.

• Inspiratory Capacity: The amount of air inhaled after a normal exhalation.

• Expiratory Capacity: The amount of air exhaled after a deep inhalation.

• Expiratory Reserve Volume: The amount of air that can be exhaled after a normal exhalation.

• Residual Volume: The amount of air remaining in the lungs after exhaling completely.

• Total Lung Capacity: The total amount of air contained in the lungs after a maximum inhalation.

3. Factors Affecting Ventilation:

• Pressure Gradient: Transpulmonary pressure is the primary factor that drives lung expansion.

• Lung Elasticity: Helps the lungs return to their original volume after expansion.

• Airway Resistance: Affects the speed of ventilation.

• Respiratory Muscle Activity: The diaphragm and external intercostal muscles participate in inhalation, while the internal intercostal muscles and abdominal muscles participate in exhalation.

• Surfactant: Helps reduce alveolar surface tension, preventing alveolar collapse.

4. Respiratory Regulation:

• Respiratory Center: Located in the medulla, automatically regulates breathing rhythm.

• Chemoreceptors: Located in the carotid bodies, aortic bodies, and cerebrospinal fluid, sensitive to the levels of O2, CO2, and blood pH.

• J Receptors: Located in the lung interstitium, respond to lung distention.

• Neural Factors: The sympathetic and parasympathetic nervous systems regulate breathing.

5. Gas Transport:

• Oxygen: Mainly transported by hemoglobin in red blood cells, with a small portion dissolved in plasma.

• Carbon Dioxide: Transported in the form of bicarbonate ions (HCO3-), dissolved in plasma, and bound to hemoglobin.

6. Gas Exchange:

• Gas exchange occurs in the alveoli, through passive diffusion, from areas of high concentration to areas of low concentration.

7. Respiratory Parameters:

• Minute Ventilation: The amount of air exchanged in one minute.

• Alveolar Ventilation: The amount of air that reaches the alveoli.

• Respiratory Rate: Number of breaths per minute.

• Dead Space: Non-gas-exchanging area in the airway.

8. Respiratory Disorders:

• Pneumonia: Infection in the lungs.

• Asthma: Bronchospasm due to allergy.

• Chronic Obstructive Pulmonary Disease (COPD): Decline in lung function due to airway obstruction.

• Respiratory Failure: Reduced gas exchange capacity.

Note: This is a brief summary of respiratory physiology. For a deeper understanding of specific aspects of respiratory physiology, you should consult more specialized literature.