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135 Cards in this Set
- Front
- Back
_____ maintain patency of airway?
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Pharyngeal muscles
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Sustained tonicity of _____ muscle keeps tongue away from posterior pharyngeal wall?
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genioglossus
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During inspiration, what are the actions of diaphragm, external intercostals, scalene, & serratus?
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-Diaphragm constricts & depresses floor of thorax (1.5-7cm)
-External intercostals constrict & elevate ribs -Scalene elevates 1st 2 ribs. -Serratus posterior superior elevates ribs up & out to expand chest. |
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During inspiration, expansion of the thorax incr/decr. vol. of thoracic cavity & incr/decr. intrathoracic & intrapleural pressure?
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Increase thoracic vol. & decrease intrathoracic & intrapleural pressure
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Muscles of inspiration (5)?
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Diaphragm, external intercostals, scalene, serratus posterior superior
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Expiration active or passive in supine & sitting position?
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Sitting - active
Supine- passive |
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Type 1 fibers?
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-Fatigue resistant
-Slow response, slow twtich |
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Type 2 fibers?
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-Rapid response, fast twitch
-Susceptible to fatigue -Produce strength -Allow muscle to produce greater force |
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Most important inspiratory accessory muscle during labored breathing?
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Cervical strap muscles
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Inspiratory labored breathing muscles & their function?
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Cervical strap muscles, sternocleidomastoid muscles elevate rib cage, scalene muscles prevent inward displacement of ribs
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Muscles of expiration during labored breathing?
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Internal intercostals, rectus abdominis, & transverse thoracic
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Rythmic cycling pattern of inspiration is maintained by?
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Dorsal respiratory group
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Rythmic cycling pattern of expiration is maintained by?
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Ventral respiratory group
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The automatic rhythm of ventilation can be modified by afferent information from _____ & ______ nerve fibers?
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Vagal & glossopharyngeal
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Responsible for fine tuning ventilation?
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pons
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2 areas of pons that fine tune rate & rhythm & their action?
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-Lower apneusic (excitatory)sustains inspiration
-Upper pneumotaxic (inhibitory)limit depth of inspiration |
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Central chemoreceptors
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-Located in medulla
-Respond to H+ changes in CSF -Activity is depressed by hypoxia -Co2 has potent but indirect effects |
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Peripheral chemoreceptors located?
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-Carotid & Aortic bodies
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Aortic & carotid bodies are stimulated by changes in (4)?
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PaO2, PaCO2, pH, & arterial perfusion pressure
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Peripheral chemoreceptors located?
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-Carotid & Aortic bodies
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Principle peripheral____ chemoreceptor most sensitive to _____?
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Carotid bodies are most sensitive to PaO2
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Peripheral chemoreceptors also stimulated by ____ & ____? Carotid bodies are depressed by _____ & ____?
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- stimulated by cyanide & doxapram
-depressed by anesthetics & carotid surgery |
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Peripheral chemoreceptors relate info to central receptors via ?
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glossopharyngeal N.
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Deflation reflex?
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Lung receptors that shorten exhalation when lung is deflated.
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Lung receptors function?
Impulses carried by _____? |
-Inhibit inspiration during max. lung inflation
-Shorten exhalation when lung is deflated (deflation refelx). -Vagus N. |
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Left lung smaller/bigger than right & why?
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-Smaller (9 lobules)to accomodate heart.
-Right lung (10 lobules) |
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Lingula?
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-Projection of upper lobe of left lung that is homologous to middle lobe
-Not a lobe but similar to right middle lobe. |
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Hilum?
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Aka root of lung, point of entry for bronchi, vessles, & nerves into each lung
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Visceral pleura?
Parietal pleura? |
-Visceral covers surface of lungs
-Parietal covers surface of thoraic wall -Pleural cavity contains pleural fluid -Pleural fluid acts as lubricant b/w visceral & parietal |
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Tracheobronchial tree is composed of ____ & ____?
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-columnar epithelium & glands that produce mucous & serous(clear plasma) fluid
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Trachea enters superior mediastinum & bifurcates at ?
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T4
1/2 of trachea is intrathoracic & 1/2 extrathoracic. |
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How many lung generations or divisions?
No gas exchange occurs at generation ___ to ___? |
23 generations
No gas exchange at 1-16 (mainstem bronchi to terminal bronchiole) |
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Gas exchange occurs starting at?
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Respiratory bronchiole (generation 17)to alveolar sac
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Angle of bifurcation & length of R. & L. bronchus?
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-R. bronchus: 25 degree angle w/ greater diameter & 2.5cm length.
-L. bronchus: 45 degree angle & 5cm length |
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Bronchiole?
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-1mm in diameter
-Do not have cartilaginous support -Highest proportion of smooth muscle -Subdivide to become terminal bronchiole |
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Last component of conductive airways?
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Terminal bronchiole
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Transitional airways include?
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Respiratory bronchiole (2-3 divisions) then becomes alveolar ducts
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Last subdivisions of respiratory airways?
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Alveolar sacs
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How many alveoli does 1 alveolar sac contain?
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17 alveoli
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Alveolar size depends on ____ & ____?
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-Gravity & lung volume
-Size varies w/ positioning (largest at apex when sitting) |
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Type 1 pneumocytes?
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-Flat & form tight junctions
-Form structure of alveolar wall -Prevent passage of lg. molecules into alveolus |
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Type 2 pneumocytes?
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-Secrete surfactant
-Divide to form type 1 -Resistant to O2 toxicity -Exist in larger # than type 1 |
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Role of surfactant?
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-Lower surface tension
-Allows membrane to expand to increase gas exchange |
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Type 3 pneumocytes?
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-Alveolar marcophages
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Pulmonary vascular system?
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-Supplies resp. bronchioles & below
-R.CO from R. vent. via PA to lung. -O2 blood is returned to L. heart via 4 pulm. veins -2 pulm. arteries deliver mixed venous blood from R. vent. to pulm. capillary bed. |
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Bronchial vascular system?
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-Blood from L. heart supplies O2 to conductive airways & pulm. vessels
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Compare blood flow, resistance, & pressure in pulm. vasculature & systemic vasculature?
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-Blood flow is equal
-Pulm. vascular resistance is lower than systemic -Lower pulm. vasculature pressure than systemic -Pulm. arteries & veins have thinner walls w/ less smooth muscle |
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Transpulmonary pressure?
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P alveolar - P intapleural
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Alveolar pressure is always lower/higher than intrapleural pressure?
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higher; this gradient is what keeps lungs inflated.
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Alveolar pressure, intrapleural pressure, & transpulmonary pressure at end expiration?
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-Alveolar pressure = 0 or 760mmHg
-Intrapleural pressure = -5cm H2O -Transpulm. pressure = 5 (sustains lung expansion) |
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During inspiration, alveolar & intrapleural pressure?
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-Alveolar pressure = -3cm H2O
-Intrapleural = -8cm H2O -Alveolar upper airway gradient is established & gas flows into alveoli |
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At end inspiration, alveolar pressure & intrapleural pressure
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-Alveolar pressure = 0
-Intrapleural pressure remains -8cm H2O -Transpulmonary = 5cm H2O(sustains lung expansion) |
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Elastic recolil of lungs is due to ___ & ___?
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1. elastin fibers
2. surface tension forces Tendency of lungs is to collapse |
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Elastic properties of chest wall are due to ____ & ____ ?
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1. bony structure that resist collapse
2. intercostal muscle tone Tendency of thoracic cavity is to expand outward |
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Lung compliance is a measure of ____?
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elastic recoil
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Compliance (formula)?
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-Change in vol./change in distending pressure
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Lung compliance (formula)?
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Change in lung vol./change in transpulm. pressure
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Lung compliance is affected by ? (list 4)
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1. lung volume
2. pulm. blood vol. 3. extravascular lung water 4. pathological processes |
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Surface tension?
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Forces exterted on the wall of the alveoli by the gas in the alveoli & fluid filled capillaries surrounding alveoli.
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Alevoli size dynamic? T/F
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-True.
-As surfactant conc. incr. alveoli size is decr. |
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Alveolar collapse is directly proportional to ____?
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surface tension
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List 4 lung volumes?
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1. Tidal vol. (TV)
2. Inspiratory reserve (IRV) 3. Expiratory reserve (ERV) 4. Residual (RV) |
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Tidal volume?
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-amt. of gas inspired or expired w/ each breath
(normal breath) |
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Inspiratory reserve vol.?
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Max. amt. of additional air that can be inspired from end of normal inspiration
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Expiratory reserve vol.?
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Max. vol. of additional air that can be expired from end normal expiration
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Residual vol.?
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vol. of air remaining in lung after a maximal expiration.
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Total lung capacity?
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after max. inspiration: vol. of air in lungs.
TLC= TV+IRV+ERV+RV |
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Vital capacity?
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after max. inspiration: max. vol. of air that can be forcefully expelled from lungs.
VC= TV+IRV+ERV |
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Functional residual capacity?
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Vol. of air remaining in lung after normal exhalation.
FRC= RV+ERV |
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Inspiratory capacity (IC)?
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Max. vol. of air that can be inspired from end expiration
IC= TV+IRV |
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FRC is directly proportional to ____?
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height
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Factors that decrease FRC (4)?
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1. obesity
2. supine/prone (10-15%) 3. lung disease affecting compliance 4. decrease diaphragmatic tone (GA further decr. by FRC by 5-10%) |
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Closing capacity?
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-vol. at which small airways begin to close in dependent parts of lung
-normally lower than FRC & not affected by positioning |
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This vol. is a function of elastic recoil affecting radial traction of small airways?
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closing capacity
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Laminar flow will convert to turbulent during?
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1. high flows
2. sharp angles(circuit) 3. changes in tube diameter |
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Where does turbulent flow occur?
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-larger conducting airways
-Trachea (low resistance) -larger bronchi to 7th gen. (incr. resistance) |
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Where does laminar flow occur?
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-Smaller airways
-small bronchioles |
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Areas of high & low resistance?
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Low resistance: trachea & main bronchus (b/c lg. diameter) & small bronchi due to lg. cross sectional area.
High resistance: medium size bronchi down to 7th gen. |
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Reynolds # < 1,000 predicts?
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laminar flow
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Explains laminar flow through cylindrical tube?
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Poiseuille's law
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Poiseuille's law
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Airway resistance is directlly r/t air viscosity & to length of tube & inversely r/t radius in 4th power
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Doubling length airway ____ resistance?
Halving radius ____ resistance? |
-Doubles
-increase by 16th fold (16x) |
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Why do small airways collapse during low lung vol. ?
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-Small airways collapse due to less radial traction increasing airway resistance
-Treat w/ PPEP (incr. lung vol. & decr. airway resistance) |
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How do airways collapse due to flow?
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High intrathoracic pressure (bucking) during forced exhalation increases airway intramural pressure & results in airway collapse & incr. resistance
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Gas transport in transitional & respiratory airways is by ____?
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diffusion
Co2 is 20x more diffusible than O2 |
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Blood flow through capillary is direclty affected by ____ & _____?
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gravity & alveolar size
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The bigger/smaller alveoli the more resistance to blood flow?
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the bigger the more resistance
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The Pulm. capillary ____ has lg. junctions that allow passage of albumin, macrophages, & neutrophils
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endothelium
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Explains laminar flow through cylindrical tube?
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Poiseuille's law
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List in order layers of respiratory membrane (8)?
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1. Alveoli
2. Surfactant 3. Alveolar epithelium 4. Alveolar basement membrane 5. Interstitial space (b/w alveolus & capillary) 6. Capillary basement membrane 7. Capillary endothelium 8. RBC |
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Pulmonary lympathics?
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-originate in interstitial space
-Lymph has high protein count -total lymph= 20ml/hr -R. lungs drains into R. lymphatic duct -L. lung drains into thoracic duct |
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Thoracic duct drains?
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-L. throrax, LUE, L. side head & neck
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Pulm. blood flow is a tight relationship b/w (3)?
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1. Pulm. artery pressure (Pa)
2. Alveolar pressure (PA) 3. Pulm. venous pressure (Pv) |
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Lung Zones?
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-Zone 1: most gravity independent (apex)
-Zone 2: from lower limit of zone 1 to upper limit zone 3 -Zone 3: most gravity dependent (bases) *Location of zone varies w/ position. |
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Zone 1?
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-No blood flow
-PA>Pa>Pv -V/Q = 1 -PA= atm. pressure & Pa=subatm. -Ventilation w/o perfussion = alveolar dead space -Alveolar pressure promotes collapse of pulm. capillaries |
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Zone 3?
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-Pa>Pv>PA
-Cont. blood flow b/c intravascular pressure is higher than alveolar pressure |
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Zone 2?
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-Located in middle
-Pa>PA>Pv -Blood flow depends on diff. b/w arterial & alveolar pressure -Flow varies w/ respiration |
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Minute ventilation?
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-The sum of all exhaled gas volumes in 1 min.
-Minute ventilation = RR x Tv -Norm = 5L/min |
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Dead Space?
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-Part of Tv that does not participate in gas exchange
-Alveolar, anatomical, & physiologic dead space |
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Physiologic dead space?
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-Sum of anatomic & alveolar dead space
-Norm.= 150mL (2mL/kg) |
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Factors that modify anatomic dead space?
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1. tracheal intubation
2. tracheostomy 3. incr. length of circuit Anatomic DS- oronasopharynx to terminal & resp. bronchioles |
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Physiologic dead space is primarily modified by changes in _____?
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alevolar dead space
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1,2,3 rule of dead space for spont. ventilating pt.?
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1mL xlb = anatomic dead space
2mL xlb = alveolar dead space 3mL xlb = Tidal Vol. |
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Why do non-dependent areas get less ventilated?
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Because intrapleural pressure is more (-) at the apex & alveoli in apices are more inflated & less compliant
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Why do dependent areas get better ventilated?
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Because less (-) intrapleural pressure at bases & alveoli are smaller therefore more compliant & have greater expansion.
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Why are alveoli at bases smaller?
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Due to lower transpulmonary pressure at the bases.
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Alveoli filling depends on (3)?
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1. inspiratory time
2. compliance 3. airway resistance |
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Pulmonary perfusion?
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-Norm. 5L/min
-100mL at a time participate in gas exchange -Systole & spont inspirations incr. pulm. blood flow |
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HPV?
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-Physiologic reflex stimulated by alveolar hypoxia
-Reduces shunting & prevents hypoxemia -Hypercapnia & acidosis also stimulate HPV -Blunted by PIA's |
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Intrapulmonary shunt?
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-Portion of CO that returns to L.heart & systemic circulation w/o being oxygenated
-Perfusion w/o ventilation |
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Relative shunt?
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-V/Q ratio is low but still exists; some gas exchange
-O2 therapy may improve |
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Absolute shunt?
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-V/Q ratio = 0
-Hypoxemia not reveresed w/ O2 -No gas exchange |
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Venous admixture?
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-5% CO normally shunted via pleural, bronchiolar, & thebesian veins into L. ventricle
-R. to L. absolute anatomic shunt -Amt. of mixed venous blood that would account for diff. b/w pulm. end capillary & arterial oxygen tension |
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Conditions that cause relative shunting?
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1. Mild. pulm. edema
2. Post-op atelectasis 3. COPD (low V/Q, perfusion w/ some ventilation) |
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Conditions that cause absolute shunt?
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1. Acute lobar atelectasis
2. Acute lung injury 3. Adv. pulm. edema 4. Consolidated pneumonia (No gas exchange) |
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Alveolar PO2 calculation?
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PAO2=FiO2(BP-PH2O)-PACo2/R
BP= 760mmHg at sea level PH2O= 47mmHg R= 0.8 PACo2 (alveolar) is same as arterial |
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Causes of alveolar dead space (3)?
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1. decr. CO (most common)
2. pulm. emboli 3. PPV |
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A-a gradient incr. w/ (4)?
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1. age
2. V/Q mismatch 3. R. to L. shunt 4. diffusion defects |
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A-a gradient does not take into account (4)?
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1. venous admixture
2. decr. CO 3. anemia 4. incr. VO2 |
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A-a gradient takes in account (is dependent on)?
Normal A-a gradient? |
-Dependent on R. to L. shunt; V/Q mismatch, mixed venous O2 tension
-Norm. = <10mmHg, may variate 5-20mmHg |
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Spirometry?
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-measures expiratory vol. & flow rates
-requires max. inspiratory & expiratory effort -detects bronchial hyperreactivity in asthma (inhaled histamine) -Used to dx obst. & restrictive lung disease -Reversibility of obst. assessed w/ bronchiodilator |
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Spirometry results?
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-Results expressed as % or absolute value
-value <80% of predicted value is abn. |
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Spirometry normal values vary depending on?
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1. gender (men bigger w/ bigger lungs)
2. race 3. age 4. height (most used to define norm. values) |
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Lung volume test?
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-Measures inhalation
-used to dx restrictive dz -pt. w/ restrictive dz = decr. vol. w/ inhal. |
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Forced vital capacity?
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-measures air vol. of a forceful inspiration/expiration
-decr. w/ restrictive dz -norm. or slightly incr. w/ COPD |
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Forced expiratory vol. (FEVt)?
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-compared w/ FVC
-decr. w/ restrictive (decr. vol. in & decr. vol. out) & obst. (lg. vol. in but exhale slowly) -Normal: can exhale 75% of FVC in 1st second of FEV - |
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FEV1/FVC?
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-normal = 75%
-COPD <75% -Normal w/ restrictive (b/c no problems exhale in 1st sec.) |
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Maximum midexpiratory flow rate (FEF 25-75%)?
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-measures forced expiratory flow during middle 1/2 of FEV
-middle 1/2 of FEV falls b/w 25-75% of FEV -Very sensitive to dx early COPD -Normal value = 100 + or - 25% or 4.7L/sec (280ml/min) -decr flow % indicates mid-size obst. -normal w/ restrictive dz |
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Flow volume loops?
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-Graphical representation og lung vol. expired during forced expiratory effort followed by a forced inspiratory maneuver.
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Flow volume loops in normal patients after a small amt. of gas has been exhaled, flow depends on (3)?
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1. airway compression
2. elastic recoil of lung 3. resistance upstream of that point |
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Effects of anesthesia on pulm. mechanics?
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-induction decr. FRC by additional 15-20%
-decr. muscle tone decr. FRC (cephald movement of dependent diaphragm at end expiration & chest wall moves inward) -No change in airway resistance due to bronchiodilator effects of PIA's |
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Effects of anesthesia on gas exchange?
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-Incr. physiologic dead space
-Incr. intrapulm. shunting -Incr. venous admixture to 5-10% -Inhibition of HPV (incr. pulm. shunt) |
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Signs & symptoms of bronchospasm?
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-delayed expiratory phase by capnograph
-high peak inspiratory pressures -wheezing |
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Treatment of bronchospasm?
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-incr. PIA
-check ETT for secretions, kinks,mucous plugs -B agonist (albuterol inh) -IV hydrocortisone (1.5-2mg/kg) |
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Differential diagnosis for bronchospasm?
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1. Pulm. edema
2. emboli 3. pneumothorax |