Term
| What separates the thoracic from the abdominal cavity? |
|
Definition
|
|
Term
| To what structures does the diaphragm muscle attach? |
|
Definition
|
|
Term
| Why does the diaphragm need to maintain its dome shape throughout respiration? |
|
Definition
| If it's flattened, it can't lift the ribs up and out. If not in a dome, during contraction the diaphragm will pull the ribs inward, and the lungs will expand into the abdominal cavity. |
|
|
Term
| Define Hoover's Sign. What is it AKA? |
|
Definition
| ribs pulled inward during inhalation, forcing lungs to expand into the abdominal cavity. AKA: Quad Gut |
|
|
Term
| What are the 2 major reasons Hoover's Sign would occur? |
|
Definition
| Paralysis of the abdominal muscles (decreased interabdominal pressure), overinflation of the lungs (as in COPD) |
|
|
Term
| Define Zone of Apposition |
|
Definition
| The space between the ribs and the diaphragm |
|
|
Term
| How does the diaphragm work to create an inhalation? |
|
Definition
| When the diaphragm contracts, it lifts the ribs, and it forces the abdominal pressure into the zone of apposition. Contraction of respiratory muscles causes negative pressure in the lungs relative to atmoshpheric pressure, so air follows the pressure gradient into the lungs. |
|
|
Term
| Describe Distensibility/Compliance. |
|
Definition
| The ease with which something (ie:the lung) is distorted. |
|
|
Term
| Relate Compliance of lung tissue to respiratory muscle workload. |
|
Definition
| The more stiff (less compliant) lung tissue is, the harder the respiratory muscles must work to create adequate negative pressure. |
|
|
Term
| A given pressure change is applied both to a deflated lung, and a nearly fully inflated lung. In which lung with the pressure change cause a lesser volume change? Why? |
|
Definition
| The nearly fully inflated lung will experience a lesser volume change with the given pressure, because as the lung inflates it becomes more stiff (less compliant). ie: It's easier to blow up an empty balloon, than a full balloon. |
|
|
Term
| A given pressure change is applied both to a deflated lung, and a nearly fully inflated lung. In which lung with the pressure change cause a lesser volume change? Why? |
|
Definition
| The nearly fully inflated lung will experience a lesser volume change with the given pressure, because as the lung inflates it becomes more stiff (less compliant). ie: An empty balloon with demonstrate a larger size change when blown into than a full balloon will with the same pressure of air. |
|
|
Term
| At rest, where are the alveoli most expanded? |
|
Definition
|
|
Term
| Why does the lung preferencially fill from the bottom up? |
|
Definition
| The lung's gravitational component. Like a slinky held from the top and allowed to dangle. the alveoli at the top of the lung are more expanded than those at the bottom (picture the wide spaces between coils at the top of the slinky vs. the narrow spaces between them at the bottom). The alveoli at the top of the lung have higher resting volume, therefore higher resting pressure than the bottom alveoli. As a result, the bottom alveoli more readily expand. (empty balloons on the bottom fill more easily than the partially full balloons at the top. |
|
|
Term
| At rest, is there a greater negative pressure at the top or the bottom of the lung? |
|
Definition
| Top. -10cm H20 vs. 2.5cm H20. |
|
|
Term
| Would a positive pressure in the intrapleural space result in an advantage or a disadvantage to a working lung? Why? |
|
Definition
| Disadvantage. The lung must be at a lower pressure in relation to the atmosphere in order to pull air in. If there is a positive pressure in the intrapleural space, the respiratory muscles must overcome not only that positive pressure, but must work even harder beyond that to create a negative pressure in order to breathe in. |
|
|
Term
| Where does surface tension exist? |
|
Definition
| At any air-liquid interface. |
|
|
Term
| Where in the lung is there surface tension? |
|
Definition
| At the alveolus/capillary bed interface. |
|
|
Term
| As surface tension decreases, what happens to the compliance of the lung? |
|
Definition
| It increases. Becomes easier to inflate. |
|
|
Term
| What happens to the surface tension of surfactant as it is compressed (as the lung deflates)? |
|
Definition
| The surface tension decreases. |
|
|
Term
| How does surfactant aid inflation of the lungs? |
|
Definition
| `Surfactant has less surfacte tension than water. So sufactant lines the alveolus to create a surface tension that is less than that of blood. This makes it easier to expland the lung. |
|
|
Term
|
Definition
| Pressure = 2xTension/Radius of alveolus |
|
|
Term
| Using the Law of LaPlace, describe how alveoli are able to maintain pressures independent of one another. (Why are alveoli able to have different pressures, rather than working together as one big balloon?) |
|
Definition
| P=2T/r. If the radius decreases, pressure will increase proportionally. Without surfactant, this increase in pressure would cause an overflow into a neighboring alveolus. But because of surfactant, when the radius decreases, surfactant compresses, allowing the tension to decrease, which allows the alveolus to maintain a stable pressure. (w/ surfactant, when r decreases t increases proportionally and p stays the same regardless of the size of the alveolus.) |
|
|
