Lec 2-3 - Mechanics of Breathing Flashcards
What is tidal volume?
Tidal Volume is the air you inhale/exhale during quiet breathing
• AVG. 450-500ml
What is residual volume?
Residual volume is the amount of air trapped in the small airways
Describe the mechanical events that occurs to allow air to enter the lungs
Diaphragm contracts, creates negative pressure around lunges, air moves in.
• increases space by ribcage expansion (bucket handle, pump handle and abdominal wall contraction)
• increases volume creates negative pressure that sucks air in
Use the P-V of the lung to explain how regional differences in lung ventilation can
affect blood gas content.
Non-dependent regions of the lung, i.e. the more superior part, is less compressed due to less pressure, so they have more air in them by default, and therefore less surface area, and less gas exchange. Compared to alveoli in the lower part of the lungs that can take in more air, and participate in more gas exchange (higher pressure)
Where does most blood flow through the lungs occur?
The greatest volume of blood flow will occur in the gravity-dependent areas of the lungs.
What is atelectasis?
a lack of air in the alveoli resulting from obstruction of the airways.
- the alveoli are deflated down to little or no volume, and they are filled with liquid.
- crackling sound during inspiration
Why do obese people have difficulty breathing?
people with obesity have a very stiff chest wall due to excessive adipose tissue
• difficulty expanding the lungs
what is the significance of FEV 1 and respiration?
FEV1, can be used as a predictor for airway disease
Describe how lung function changes in the absence of normal surfactant.
Present: surfactant functions to decrease surface tension when the radius of the alveoli is small. This increases intra-alveolar pressure of the alveolus and increases the surface area of gas exchange.
Absent: Without pulmonary surfactant, you cannot maintain equal pressure between the alveoli, as a result, small alveoli would empty air into larger alveoli with less pressure. Less surface area for gas exchange
What is the role of surfactant?
Surfactant helps to decreases surface tension in the alveoli and helps keep the pressure remains relatively equality in both the small and large alveolus
Describe the mechanical events of exhalation.
During exhalation, the diaphragm relaxes and ascends upwards into the thoracic cavity, the internal intercostal muscle help to decrease space between the ribs and the abdominal muscles help to force air out of the lungs by decreases pressure.
