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20 Cards in this Set
- Front
- Back
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Functions of lungs
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- Gas exchange
- Ventilation = frequency x breath depth - Perfusion = CO of RV - Ideal V/Q match - if volume air = volume blood flow - Maintain partial pressures of gasses in tissues (via diffusion) - O2 to tissues, CO2 back to lungs |
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Non-respiratory functions
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- Phonation
- Pulmonary defenses (innate) - Blood filter - better a clot in lungs than brain! - Acid-base buffering - Carbonic anhydrase reaction - Increased/decreased respiration - Substrate conversion = Angiotensin I -> Angiotensin II via ACE in Lungs! - Inactivate bradykinin, serotonin, Prostaglandin E and F |
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Conducting zone
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- Trachea, bronchi, bronchioles, terminal bronchioles
- "Dead space" = no gas exchange! - Generation 1-16 - Blood supply from systemic circulation - Cartilage from 1-11 - Cilia from 1-16 - As with vasculature - diameter↓, surface area↑ |
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Dead space function
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- Air conditioning!
- Heating/cooling and humidification - Inspired air = 37° by lower trachea no matter what - Fully saturated with H2O when reaches large bronchi - PH2O = 47mmHg - affects PP of O2 and CO2 |
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Muco-cilliary escalator
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- Gen 1-16
- Cilia beat synchronously to carry mucus to upper trachea - Particles reaching alveoli - engulfed by macrophages |
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Sizes, locations of trapped particles
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- Nasopharynx = >5µm
- Bronchi = 1-5µm - Alveoli = >0.1µm |
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Respiratory zone
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- Gen. 17-23 = Gas exchange!
- Blood supply - pulmonary circulation - Very large total surface area ~ tennis court! - ~1000 capillaries/alveoli - huge potential for diffusion - "Silent zone" for disease - hard to detect alveoli damage until too late |
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How do 12-23 stay open?
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- Radial traction = everything connected to everything else
- Can't collapse without pulling on something else |
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Acinus
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- Basically one respiratory unit
- Respiratory bronchiole with alveolar ducts, sacs, and alveoli |
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Alveolar-capillary interface
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- Pulmonary capillary and alveolus interface
- Alveolar-capillary membrane very thin - 2-5µm! - Disease states = can become thicker - impaired diffusion, inflation/deflation - Blood/air volume matching - key for proper diffusion |
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Alveolar surface cells
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- Primarily Type I cells
- Single layer of squamous epithelia - Cover 90-95% of alveolar surface - Type II cells - cuboidal cells - 2x as many as Type I! - Produce surfactant - Alveolar macrophages also present |
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Alveolar structural interdependence
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- Basically radial traction - alveoli help keep eachother open/closed in concert
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Emphysema (COPD)
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- Tend to lose inter-alveoli septa - lose individual alveoli
- Overall loss of interdependence - loss of elasticity/recoil - Can't get air out...easy to inflate, but can't get rid of old air |
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Functional residual capacity (FRC)
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- Amount of air left in lungs after normal breath
- Chest wall (rib cage) - wants to flare out - Lungs want to recoil - Lungs get sucked out to meet chest wall via vaccuum - FRC determined by balance of these forces! - More/less force either way affects FRC |
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Transpulmonary pressure
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- Technically, the pressure forcing the lung to expand
- Normal atmospheric pressure = 760 mmHg - At inspiration - diaphragm contracts, ribs flare out -> increased volume - If alveolar pressure = 758 and pleural space = 754 -> 4 mmHg of pressure forcing lungs open! - Lungs expand/inflate when pressure around lung is less than atmospheric |
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Pneumothorax
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- Rupture/puncture of chest wall -> air flows into pleural space
- Reduced pressure difference - reduced pull on lung - Lung shrinks below residual volume - Chest wall increases size - no pulling from lungs |
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Pressures difference when breathing normal vs. slow
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- Normal inspiration has to overcome 1) lung recoil 2) airflow resistence
- When slow breath -> no turbulence, airflow resistence - Difference between the two (graphically) = pressure needed to overcome airflow resistence |
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Muscles of breathing
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- Inspiration - ACTIVE process
- Primary = diaphragm, external intercostals - Secondary = SCM, scalenes - Seen in people with labored breathing - Expiration - PASSIVE process (mm can assist though...) - Abs can force diaphragm up - Internal intercostals reduce chest volume |
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Lung capacities
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- Normal resting tidal breath volume = 500mL
- Functional residual capacity = 2500 mL - Residual volume (remains when breathe out hard) = 1200mL - Vital capacity (total - residual) = 4800mL - Actual max volume you can move in/out - Total lung capacity = 6000mL |
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Normal blood gas partial pressures
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- Venous blood - PO2 = 40, PCO2 = 46
- Alveoli - P02 = 100, PCO2 = 40 - Arterial - PO2 = 100, PCO2 = 40 |
