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22 Cards in this Set

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epinephrine
used to treat life threatening bronchioconstrtiction such as during asthma ana anaphylactic shock (carried by people susceptible to sudden constriction) because it is a sympathetic aganist
alveolar surface tension
liquid on surface of alveoli causes them to collapse to smallest size
surfacant
lipoproteins that reduce surface tension on alveoli, allowing them to expand more easily
infant respiratory distress syndrome
premature babies that do not yet produce enough surfacant; must be ventilated for respiration
factors influencing pulmonary ventilation
A. lung compliance and elasticity-
1. lung compliance- the ease with which lungs can be expanded by muscle contraction of thorax
1a. fibrosis- decreases compliance
1b. blocked bronchi- decreases compliance
1c. surface tension- alveoli difficult to expand, surfacant eases pressure
1d. thorax inflexibility- decreases compliance
2. lung elasticity- the ease with which lungs can contract to their normal resting size (exhalation)
2a. emphysema- decreases elasticity (no cure)
3. alveolar surface tension- liquid on surface of alveoli causes them to colapse to smallest size.
3a. surfacant- lipoproteins that reduce surface tension on alveoli, allowing them to expand more easily.
3b. infant respiratory distress syndrome- premature babies that do not yet produce enough surfacant; must be ventilated for respiration
lung elasticity
the ease with which lungs can contract to their normal resting size (exhalation)
volumes, capacities, and function test
A. respiratory volumes (20 year old healthy male, 155 lbs)
1. tidal volume (TV)- normal volume of air moving in/out (0.5 L)
2. inspiratory reserve volume (IRV)- volume inhaled AFTER normal tidal volume when asked to take deepest possible breath (2.1 - 3.2 L)
3. expiratory reserve volume (ERV)- volume exhaled AFTER normal tidal volume when asked to force out all air possible (1 - 2.0 L)
4. residual volume (RV)- air that remains in lungs even after totally forced exhalation (1.2 L)
forced expiration
contraction of abdominal wall muscles (i.e. obliques & transversus abdominus) further DECREASES volume beyond relaxed point = further INCREASE in pulmonary pressure = more air moves out
factors facilitating lung movement AWAY from thorax wall
1. elasticity of lungs allows them to assume smallest shape for given pressure conditions.
2. fluid film on alveoli allows them to assume smallest shape for given pressure conditions
volume/pressure & inspiration/expiration-
A. boyle's law on volume/pressure relationships-
1. volume is INVERSELY proportional to pressure
1a. increase in volume = decrease in pressure
1b. decrease in volume = increase in pressure
1c. volume change = pressure change, gas flows to equalize the pressure
2. simple example of boyle's law =
plastic bag with tube in the top, as bag expands by pulling, gas moves IN, as bag shrinks by squashing, gas moves OUT
inspiration
1. diaphragm muscle contracts, increasing thorasic cavity size in the superior-inferior dimension
2. external intercostal muscles contract, expanding lateral & anterior-posterior dimension
3. INCREASED volume (about 0.5 liter)
DECREASED pulmonary pressure (-1 mm Hg) air rushes into lungs to fill alveoli
4. deep/forced inspirations- as during exercise and pulmonary disease, scalenes, sternocleidomastoid, pectorals are used for more volume expansion of thorax
expiration
1. quiet expiration (exhalation)- simple elasticity of the lungs DECREASES volume. INCREASED pulmonary pressure = movement of air out of the lungs
2. forced expiration- contraction of abdominal wall muscles (i.e. obliques & transversus abdominus) further DECREASES volume beyond relaxed point = further INCREASE in pulmonary pressure = more air moves out
quiet expiration (exhalation)
simple elasticity of the lungs DECREASES volume. INCREASED pulmonary pressure = movement of air out of the lungs
Factors holding lungs against the thorax wall
1. surface tension holding the "visceral" and "parietal" pleura together
2. intrapulmonary pressure Always slightly greater than intrapleural pressure by 4 mm Hg
3. atmospheric pressure acting on the lungs
3a. atelectasis (collapsed lung)- hole in pleural "balloon" causes equalization of pressure and collapse of the lung
3b. pneumothorax- abnormal air in the intrapleural space, can lead to collapsed lung
The mechanics of breathing- Relationships of pressure
1. atmospheric air pressure 760 mm Hg (st sea level)
2. negative air pressure- less than 760 nn Hg
3. possitive air pressure- more than 760 mm Hg
4. intrapleural pressure- pressure within the pleural "ballon" which surrounds the lung
5. intrapulmonary pressure- pressure within the alveloi (tiny sacs) of the lung itself
atmospheric air pressure
760 mm Hg (at sea level)
negative air pressure
LESS than 760 mm Hg
positive air pressure
more than 760 mm Hg
intrapleural pressure
pressure within the pleural "balloon" which surrounds the lung
intrapulmonary pressure
pressure within the alveloi (tiny sacs) of the lung itself
atelectasis (collapsed lung)
hole in pleural "balloon" causes equalization of pressure and collapse of the lung
pneumothorax
abnormal air in the intrapleural space, can lead to collapsed lung