The respiratory systemThe respiratory system

Respiration:Respiration:

• 4 components:4 components:

• VentilationVentilation

• DiffusionDiffusion

• O2 and CO2 transportO2 and CO2 transport

• Utilization of O2 and generation of Utilization of O2 and generation of CO2CO2

Ventilation:Ventilation:

• Respiratory center in brainstemRespiratory center in brainstem

• Motoric neuronsMotoric neurons

• Peripheral nerve: Phrenic nervesPeripheral nerve: Phrenic nerves

• DiaphragmDiaphragm

• Chest wallChest wall

• AirwaysAirways

• AlveoliAlveoli

Lung volumes:Lung volumes:

• 4 4 • Tidal volume: Tidal volume: the volume of air moving the volume of air moving

into and out of the lungs during a normal, into and out of the lungs during a normal, relaxed ventilatory effort. (500 ml)relaxed ventilatory effort. (500 ml)

• Inspiratory reserve volume:Inspiratory reserve volume: the volume the volume of air that can be inspired during a of air that can be inspired during a maximal inspiratory effort in excess of the maximal inspiratory effort in excess of the tidal volume. (2L)tidal volume. (2L)

• Expiratory reserve volume: Expiratory reserve volume: volume volume of air expelled after a maximal of air expelled after a maximal expiratory effort in excess of the tidal expiratory effort in excess of the tidal volume.(1L)volume.(1L)

• Residual volume: Residual volume: volume of air volume of air remaining in the lungs after a maximal remaining in the lungs after a maximal expiratory effort. Can`t be expelled.(1L)expiratory effort. Can`t be expelled.(1L)

Lung capacities:Lung capacities:

• Total lung capacity: Total lung capacity: TV + IRV + ERV + TV + IRV + ERV + RV.RV.

• Inspiratory capacity: Inspiratory capacity: TV + IRVTV + IRV

• Vital capacity: Vital capacity: IRV + TV + ERVIRV + TV + ERV

• Functional residual capacity: Functional residual capacity: ERV + RVERV + RV

FRC:FRC:

• Amount of air remaining in the lungs Amount of air remaining in the lungs after a normal, relaxed expiratory effort.after a normal, relaxed expiratory effort.

• At FRC the respiratory system is in At FRC the respiratory system is in equilibrium. The tendency of the lungs equilibrium. The tendency of the lungs to collapse are balanced by the to collapse are balanced by the tendency of the thoracic wall to expand.tendency of the thoracic wall to expand.

Physiological disturbances Physiological disturbances affecting ventilation:affecting ventilation:

• Brainstem:Brainstem: Respiratory center. Bleeding, Respiratory center. Bleeding, tumor, raised intracranial pressure with tumor, raised intracranial pressure with herniation.herniation.

• Motoric neurons in spinal cord:Motoric neurons in spinal cord: Poliomyelitis, motor neuron disease, trauma Poliomyelitis, motor neuron disease, trauma etc.etc.

• Peripheral nerve: Phrenic nervesPeripheral nerve: Phrenic nerves. .

• Diaphragm: Diaphragm: MyopathyMyopathy• Chest wall: Chest wall: Rib fractures, pleural Rib fractures, pleural

effusion, pneumothorax, effusion, pneumothorax, hemothorax, mesothelioma.hemothorax, mesothelioma.

• Airways: Airways: Asthma, COPD, upper Asthma, COPD, upper airway obstruction.airway obstruction.

• Alveoli: Alveoli: Filled by blood, fluid, pus, Filled by blood, fluid, pus, tumor, protein etc..tumor, protein etc..

Physiological lung function Physiological lung function tests:tests:• Ventilatory function:Ventilatory function: Assess flow via flow-volume Assess flow via flow-volume

loop- FEV1. Assess adequacy of ventilation with loop- FEV1. Assess adequacy of ventilation with PaCO2.PaCO2.

• Diffusion: Diffusion: Assess with CO-diffusion test: DLCO.Assess with CO-diffusion test: DLCO.

• Pulmonary perfusion: Pulmonary perfusion: Ventilation-perfusion scan. Ventilation-perfusion scan. Inhaled radioactive xenon matched with technetium.Inhaled radioactive xenon matched with technetium.

• Structure of lung: CTStructure of lung: CT• Ciliary function testsCiliary function tests• Arterial blood gas analysisArterial blood gas analysis