Lecture 19- Lungs Flashcards
Why is the left lung smaller than the right?
Because of the position of the heart
The lungs occupy all of the thoracic cavity except for?
The mediastinum
How is each lung suspended to its own pleural cavity?
Vascular and bronchial attachments called the lung root
Pulmonary network
Carrie’s systemic blood to lungs for oxygenation
Bronchial arteries
Provide systemic blood to lung tissue
Parietal pleura
covers the thoracic wall, the diaphragm and around the heart between the lungs
Visceral pleura
covers the external lung surface
Pleural fluid
lubricates the space between the pleurae to allow friction-free movement during breathing.
Lung compliance (lung stretch)
determined by distensibility of lung tissue and the surrounding thoracic cage and alveolar surface tension.
Tidal volume
amount of air that moves in and out of the lungs with each breath during quiet breathing.
It averages 500 mL per breath.
Inspiration reserve volume
the amount of air that can be inspired beyond the tidal volume.
Expiratory reserve volume
the amount of air that can be evacuated from the lungs after tidal expiration.
Vital capacity
sum of tidal volume, inspiratory reserve, and expiratory reserve volumes and is the total amount of exchangeable air.
Residual volume
volume of air remaining in the lungs after maximal forced expiration.
Total lung capacity
sum of all lung volumes.
Anatomical dead space
volume of the conducting zone conduits, roughly 150 mL, that doesn’t contribute to gas exchange in the lungs.
Respiratory pressures
A negative pressure indicates that the respiratory pressure is lower than atmospheric pressure.
Intrapulmonary pressure
pressure in alveoli, which rises and falls during respiration, but always eventually equalizes with atmospheric pressure.
Intrapleural pressure
pressure in the pleural cavity. It also rises and falls during respiration, but is always less than intrapulmonary pressure.
Negative intrapleural pressure is due to?
The recoil force and surface tension of alveolar fluid in the lungs.
The natural tendency of the chest wall to pull outward.
Transpulmonary pressure
difference between intrapulmonary and intrapleural pressure:
the greater the transpulmonary pressure, the larger the lung volume.
Pulmonary ventilation
mechanical process causing gas flow into and out of the lungs according to volume changes
Boyles law
states that at a constant temperature, the pressure of a gas varies inversely with its volume. Pressure changes lead to gas flow.
What happens during quiet inspiration?
diaphragm and intercostal muscles contract, resulting in an increase in thoracic volume, which causes intrapulmonary pressure to drop below atmospheric pressure, and air flows into the lungs.
What happens during forced inspiration?
accessory muscles of the neck and thorax contract, increasing thoracic volume beyond the increase in volume during quiet inspiration.
Quiet expiration
passive process that relies mostly on elastic recoil of the lungs as the thoracic muscles relax.
Forced expiration
active process relying on contraction of abdominal muscles to increase intra- abdominal pressure and depress the rib cage.
What do non respiratory air movements cause??
movement of air into or out of the lungs, but are not related to breathing (coughing, sneezing, crying, laughing, hiccups, and yawning).
Airway resistance
friction encountered by air in the airways; gas flow is reduced as airway resistance increases.
Insignificant for two reasons:
Upper airways very large diameter
Lower airways are smaller but very numerous
Alveolar surface
Tension due to water in the alveoli acts to draw the walls of the alveoli together, presenting a force that must be overcome in order to expand the lungs.
Surfactant
produced by type II alveolar cells, reduces alveolar surface tension to an optimal amount.
