Respiratory System

RESPIRATORY SYSTEM

at a glance…

Upper – Nose & Pharynx

Lower – Larynx, Trachea, Bronchi, Bronchioles, Lungs

The entire respiratory system is separated into two parts, the conductive, and the respiratory parts.  The conductive is everything that is connected from the nose to the terminal bronchioles.  Air is moved throughout the conductive parts, but O2 and CO2 are not exchanged.

This lack of gas exchange gives rise to the name dead space.  The dead space of the lungs is approximately 150 ml.

Conductive – Nose, Pharynx, Larynx, Trachea, Bronchi, Terminal Bronchioles

Respiratory – Respiratory Bronchioles, Alveolar Duct, Alveolar Sac

The tissue that the respiratory system is comprised of becomes less complex, or simpler, the closer it gets to the alveoli.  The alveolar wall has a single layer of simple tissue to allow for gas exchange.  Some of this is thought to occur in the thin walls of the respiratory bronchioles as well.

Ø    The right primary bronchus is shorter, wider, and straighter than the left.  Since it is more inline with the trachea, endotracheal tubes, that are advanced too far, commonly end up in the right primary bronchus.

Ø    The right lung has three lobes, and the left has two.

The Lungs

The serous lining of the lungs is called the pleura.  This reduces friction during the repetitive motion from breathing.

-       Visceral Pleura is in direct contact with lung

-       Parietal Pleura surrounds the visceral pleura with a space in between.

Pathologies

Pleurisy – Infection with the pleura – treated with antibiotics

Pneumothorax – Air within the pleura – treated with surgery/decompression

Pneumonia – Infection of the lung tissue – treated with antibiotics

Pleural Effusion – Fluid within the pleura – treated with thoracentesis

Pulmonary Ventilation

Pulmonary ventilation is simply the movement of air in and out of the lungs.  Also known as inspiration/expiration or inhalation/exhalation.

External Intercostals – Normally used for ventilation.  Increases volume of the chest.

Factors that effect ventilation:

-       The amount of alveolar fluid vs. the amount of surfactant.

-       Compliance of lung  – ease of expansion

-       Airway resistance – the lumen of the bronchioles

* When there is an increase in ventilatory effort, accessory muscles are used in an effort to increase the volume of the chest.

Accessory Muscles

-       Sternocleidomastoid – Pulls on the sternum

-       Scalene – Pulls on ribs one and two

-       Pectoris Minor – Pulls on ribs three, four, and five

Lung Volumes

Total Lung Capacity  (TLC)	6.0 L (Male) 4.7 L (Female)	The maximum volume  of air that can be in the  lungs at the end of  maximal inspiration.
Vital Capacity (VC)	4.6 L (Male) 3.6 L (Female)	The amount of air that  can be inspired after  maximal inspiration
Functional Residual  Capacity (FRC)	2.4 L (Male) 1.9 L (Female)	The amount of air left  in the lungs after a  tidal breath out.
Tidal Volume (TV)	500 ml (Male) 390 ml  (Female)	The amount of air  moved in and out  during normal  respiration.
Anatomical Dead  Space	150 ml (Male) 120 ml  (Female)	The volume of the  conductive airways.