Ch. 13 Pulmonary Dynamics Flashcards
(14 cards)
External Respiration
Supported by the nose, larynx, rib cage, and intrapleural negative pressure (created by lymphatics and muscles htat serve as effectors of resp.)
Turbinates or Conchae in the nose modifies ambient air by using turbine action to remove solid particles.
As air moves down the tracheobronchial tree, muco-ciliary action further removes particulate matter.
The larynx guards the tracheobronchial tree and will open and close by aciton of the vocal cords .
The epiglotis also acts as a cover to prevent food particles from entering trachea.
Anatomy of the Tracheobronchial Tree
Begins with the bifurcation of the trachea(carina)
R main bronchus is shorter and, broader, and in line with the trachea than the left.
Segmented further in terminal bronchioles, which feed the alveolar ducts.
Alveoloar ducts feed air tothe alveoil.
Atelectasis
Because of their size, they are succeptible to collapse by the formation of hydrogen by the water film.
To combat, alveolus has type 2 cells that produce surfacant that break up hydrogen bonds.
Interalveolar pores of Kohn
help percolate air between full alveoil and those do not fill normally.
**Intrapleural Space **
The Intrapleural space (IPS) has a slightly negative pressure compared ot hte ouside (760 -1), referred to as -1 mm Hg.
Outside air (760 mm Hg at sea level) will fill lungs somewhat allowing for residual volume.
How Air Moves
Inhalation begins as diaphram contracts (flattens) and expands the IPS superior-inferiorly). Rib cage expands laterally increasing diameter of IPS. Pressure of IPS drops to -2.5 to -4 mm Hg, allowing more air to enter lungs until pressure is equilibrated.
Exhalation occurs as diaphram relaxes, ribcage and alveolar walls recoil, removing alveolar air.
**Henry’s Law of Gases **
At a given temperature, the amount of gas dissolved in a volume of liquid is proportional to the partial pressure exerted by the gas in equilibrium with that liquid.
Since 20.99% of the atmosphere is O2, the O2 pressure is actually 159 mm Hg (20.99% of 760 mm Hg)
This means even a few mm pressure difference across the respiratory surface can be huge when it comes to transfer of O2 from air to blood at the alveolar level.
Flail Chest
Caused by multiple rib injuries.
Can cause ribcage to retract on inhalation and expand on exhalation (paradoxic respiration)
Shallow Water Drowning
If a diver waits too long to come up for air in a deep swimming pool (12-15 ft), the water decompression can cause air expanding in lungs to where there is very little oxygen concentration forcing person to breathe in water, resulting in drowning close to the surface.
SCUBA Diving
Short Dives (up to 30ft): Pure O2 used but prolonge use can cause psychological (8 hr) and physiological (24 hr) addiction.
Compressed air is used as nitrogen is 78% of air but at high pressures neded to get air into ungs N2 dissolves into blood and can cause N2 narcosis which can vary between divers but by 200 ft it becomes unbreathable.
Past 200 ft dives: Helium and O2 mixture used until 400 ft. Helium can dissolveinto the blood and causes issues with manual dexterity.
SCUBA divers are warned against flying within 48 hours of a water adventure as sudden elevation change can cause a further decompression and more N2 is expressed. Can cause muscle cramping, joint pain.
Laughing Gas
Occassional tradgey can occr where the peson on N20 (insoluble), is taken off the gas but doesnt recieve enough O2 - can displace the O2 in lungs causing person to asphyxiate.
O2 must be maintained and increased in needed to keep the person congrtable as their body expels the N20 from their bodies.
Elevation Changes
At elevations, the diff in pressures of O2 in the lungs v. blood is lessened making it difficult for existing muscle effort to bring O2 into blood.
Humans cannot function effectively past 9000 = 10000 feet w/ comressed gas inhalation.
High Elevation (above 6000 ft) can result in respiratory distress for those that are sensitive.
All people at sea level have to make adjustments in respiratory effort and changes.
Spirometry
Used to assess physiological and clinical status of lung function.
TV: TIdal Volume - volume of air moved normally in one breath. (500 ml average)
IRV: Inspiration above the normal intake of breath.
ERV: Expiration beyond the normal exhalation of breath.
VC: Vital Capacity - max vol of air that can be moed in a normal breath.
Dead Space
Amount of air not in contact with a respiratory surface of lungs.
Anatomical: air held btwn non-breathable surfaces lining tracheabronchial tree up to and including terinal bronchioles.
Physiological: volume in reathable space but w/o the associated perfusion by blood to allow for gas exchange. V:Q (ventilation to perfusion ration normally 1:1) would be greater than 1.
Pathological: due to pulmonary embolism causes clots results in blockage. V:Q ratio >1
