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69 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What happens when the diaphragm contracts and the chest wall expands?
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Negative pressure is created in the lungs and air flows in.
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What happens when the chest and diaphragm relaxes?
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Positive pressure is created and the tidal volume of air is expelled.
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Differences between R and L bronchus?
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The right brochus is a straighter pathway into the lungs than the left and food can get lodged down here more easily.
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What is the main purpose of cilia and how far do they extend in the respiratory pathways?
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The main purpose of cilia is to propel foreign particles trapped to the mucus outwards. The extend all the way down to the respiratory bronchioles where they end.
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What are the 2 zones and 6 structures of the airway system?
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Zone 1 = conducting zone
Zone 2 = Respiratory Zone Zone 1 Structures = Trachea, Bronchi, and bronchioles Zone 2 Structures = Respiratory bronchioles, alveolar ducts and alveolar sacs |
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Function of smooth muscle in the airways?
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It controls the diameter of the airways through sympathetic and parasympathetic innervation.
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Sympathetic nerves in the airways cause?
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Relaxation of the smooth muscle using the Beta 2 receptors. Albeuterol is a Beta 2 agonist that helps asthma patients.
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Cartilage in the airways does what?
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It gives structure and support down to the trachea and bronchi. After this point smooth muscle, surfactant, and attachment to other structures are sufficient.
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What happens in the conducting zone?
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Air gets cleaned and humidified, no gas exchange
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What happens in the respiratory zone?
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Also called the alveolar space the respiratory zone allows gas exchange in the alveolar sacs and ducts.
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Calculation of Alveolar volume?
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Va = tidal volume - dead space
Normal = 500ml - 150ml = 350ml 500ml of air does reach the alveoli but some of it was already used. |
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Average FRC volume?
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about 3000ml
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How to calculate alveolar ventilation(Vdota)
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Vdota = (Vt-Vd) * f
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What is alveolar ventilation(Vdota)?
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The amount of fresh air that reaches the lungs in breaths per minute.
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What is the paper bag effect?
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Emphysema patients have lost the elastic recoil in their lungs so the lungs act like a paper bag and fill up easily. Without the elasticity they do not expire well and have a larger Vd.
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A large dead space and Vdota
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A large Vd would cause hypoventilation because the patient never expels enough gas and they have an increase CO2 content in the mixed gas.
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Anatomical Dead space
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Generally it's about 1/3 tidal volume.
Vdotd = Vd * f |
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Type 1 v. Type 2 pnuemocytes
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Type 1 = SSq epithelium
Type 2 = SC epithelium and they secrete surfactant and are located in the respiratory zone |
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What are pores of kohn?
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They are the interalveolar connections that allow the communication of gases between neighboring alveoli. They can also allow fluids and bacteria through. This is a secondary system to increase gas exchange is the lungs are partially deflated.
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Alveolar macrophages
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Begin as monocytes in the circulatory system. When needed they move into the tissue where they become macrophages and attack foreigners.
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Purpose of dead space
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It is usually located in the conducting airways to gas exchange. It warms and humidifies the incoming air. It can also help clean the inspired air from contaminants before entering the lungs.
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What is anatomical dead space?
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The gas in the conducting areas of the respiratory system which do not come into contact with the alveoli.
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Describe the Fowler method of measuring anatomical dead space.
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It does not measure physical dead space. The subject breaths in about 350mL of pure O2. They are hooked up to a nitrogen meter. They exhale and initially the exiting air will be pure O2 from the Vd. The nitrogen rises sigmoidally as the previously inhaled air(that is mixed) brings the Nitrogen to its atmospheric levels. Drawing a line halfway through this curve givefs the dead space volume.
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Physiological dead space.
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All the air in the respiratory pathways that doesn't undergo gas exchange, including dead or inadequately perfused alveoli(the top of the lungs). It is the sum of the anatomical and alveolar dead space.
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Bohr method of measuring physiological dead space.
Bohr and paco |
Vd = Vt(PaCO2-PeCO2)/PaCO2
Bohr and PaCO were friends till PaCO died. |
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How to get the physiological dead space fraction?
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We use CO2 because the inspired fraction will be 0
Vd/Vt= (PaCO2-PeCO2)/PaCO2 Should be about 25% of Vt |
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What is effective ventilation?
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Another name for alveolar ventilation.
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What happens with a low alveolar ventilation?
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PO2 will decrease, ventilation will decrease, Low V/Q, and PCO2 will increase.
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What is the minute volume(Vdot)?
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Vdot = Vt * frequency(rr)
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What is the ideal gas law?
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PV = nRT
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What is Boyles law of pressures and volumes?
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P1V1 = P2V2
The amount of gas does not change when the pressure and volume change at a constant temp. |
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Daltons law of partial pressures?
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Ptotal in a closed system = summation of all the partial pressures of gasses
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Henry's law of gases in liquid phases?
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Gases in liquid phase
Conc = solubility * PO2 At equilibrium the solubility of liquids and gases increase in a one to one relationship. |
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Concentration v. Binding of O2
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The concentration of O2 in the blood is barely detectable v. the binding capacity of O2 in the blood.
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What is the inspiratory capacity(IC)?
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The max volume of air inhaled after a normal tidal breath out.
About 4.1L |
TV + IRV
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What is the functional residual capacity(FRC)?
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The amount of air left in the lungs after a normal tidal breath out.
About 2.4L |
ERV+RV
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What is the inspiratory reserve volume(IRV)?
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Additional amount of air that can be inhaled after a normal tidal breath in.
About 3.6L |
(VC-(TV+ERV))
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What is the expiratory reserve volume(ERV)?
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The amount of air that can be breathed out after a normal expiration.
About 1.2L |
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What is residual volume(RV)
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The amount of air left in the lungs after the ERV or maximum expiration.
About 1.2L |
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What is forced vital capacity(FVC)?
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Amount of air forced out of the lungs after maximal inspiration.
About 4.8L |
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What is the Vital Capacity(VC)?
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The amount of air forced out of the lungs after maximal inspiration, based on completness.
About 4.6L |
IRV+TV+ERV
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What do we measure the FEV1 for?
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The forced expiratory volume after one second is used to determine about obstructed airways. Take this number and divide it by the FEVtotal. The result should be about 80%, if it is less or more than this than there is a problem.
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Helium Dilution techneque to measure FRC and lung volume.
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Patient expires to his FRC and then breathes in helium from a spirometer. The initial volumes and concentrations are known and the final volume gathered uses boyles law. V2=(C1V1)/V2
This gives us a calculation of the patients FRC. |
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Forced expiration and spirometry units
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Units here are in Vol/Time = Flow.
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Flow volume loop
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Way to measure FVC from right to left in a loop with expiratory and inspiratory capacities.
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Age and lung volumes
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With age RV increases and TLC also. VC will decrease.
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Reasons for reduced VC
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Skeletal abnormalities(scoliosis), Weak respiratory muscles(polio, myasenthia gravis), Lung diseases(Fibrosis, effusion, edema, collapsed lung), Severe airway obstruction(asthma, brochitis, emphysema, bronchiectasis)
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Broncheomalacia
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Floppy airways or weak cartilage in the walls of bronchial tubes. Can trap air in and increase RV. These patients have a barrel chested appearance.
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Restrictive lung disease and RV/TLC ratio.
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TLC is reduced, RV increases, RV/TLC is the same because change is proportional.
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Obstructive lung disease and RV/TLC
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TLC increases, RV greatly increases, RV/TLC goes up.
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What is lung compliance?
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The ability of the lungs to stretch in response to a change in the pulmonary volume because of a change in pressure. V/P
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What is lung elastic recoil?
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Pel is the pressure of the lungs to to its tendency to collapse.
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Symbols for Pressures in lungs that cause airflow.
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Pl = transpulmonary
PA = alveolar Ppl = pleural Pta = transairway Paw = airway |
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Pressure difference and suction inside the chest of the pleural cavity
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The lung is trying to collapse inwards as the chest is trying to expand outwards. This causes a suction and negative pressure inside the pleural cavity that holds them together.
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Pneumothorax
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If you puncture the pleural cavity then the negative pressure is released, the suction is lost and the lungs collapse while the chest expands. Fix this by sucking the air out with a vacuum and recreating that negative pressure.
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Expiration timing v inspiration. Relate normal to diseases
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Normally expiration time is a little longer than inspiration. In obstructive lung disease this time increases markedly. During restrictive lung disease this time can decrease because less volume and stiffer lungs force the air out quicker.
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Change in complainces between the bottom and top of the lungs
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At the bottom of the lungs a small change in pressure illicits a large change in the volume. At the top of the lung a large change in pressure illicits a small change in volume. This is due to the triangular shape. So the top has low compliance and the bottom has high compliance.
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Pressure and initiation of breath.
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At rest the PA = 0
A small expansion of the diaphragm causes a small decrease in Ppl but the alveoli haven't moved at all. This builds a negative pressure for the air to follow. |
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How does the FRC relate to pressure and exertion?
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At FRC the elastic recoil and chest expansion pressure are equal and opposite and there is no exertion by respiratory muscles. This is because the lungs are as empty as they can be without collapsing.
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Restrictive lung disease and FEV1/FEV ratio
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Airways are ok here but the lung tissue is stiff. So you can pull in air ok but due to reduced compliance and lung volume you force the air out quicker than normal.
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Surfactant purpose
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Surfactant helps to equilibriate the pressures between large and small alveoli by creating a variable surface tension.
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Laplace law with no surfactant
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States that a sphere with a smaller radius will have a greater pressure. Surfactant helps to get rid of this law and allow our alveoli to remain stable.
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Type 2 alveolar cells
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Synthesize surfactant, type 2 pneumocytes
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Factors affecting airway resistance
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Density of inspired gas
Lung volume Reduction in PCO2 Sym and parasym innervation Agents |
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Airway resistance(R)
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R = driving pressure/flow
(Pin-Pout)/Vdot |
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Flow
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Flow = (velocity * area)/time
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What must the airways do to work?
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Work = P * vol
To do work respiratory fibers must overcome stretching the fibers(Pel) and Paw |
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Peak expiratory flow (PEF in the flow volume loop)
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PEF is the peak expiratory flow during forced expiration. This point occurs quickly from R to L before much change in volume has occured. The remaining FVC occurs and is effort independent because of dynamic airway compression.
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Peak inspiratory flow (PIF in the flow volume loop)
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PIF is maintained for a longer period of volume(time) than the PEF because the lungs are distended and the need to keep effort.
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