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67 Cards in this Set
- Front
- Back
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During the initial phase of inspiration, where in the body does pressure rise
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Intra-abdominal pressure
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What mechanism is primary responsible for expiration in a subject at rest
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Elastic recoil
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How would elevation of the larynx affect inspiration
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It would occlude the glottis and prevent inspiration
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When does dry inspired air at -10C reach body temperature and 100% humidity
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By the time it elaves the nasal cavity
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What is the function of the external intercostal muscles during respiration
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Elevate the ribs and stabilize the intercostal space during inspiration
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What causes abdominal breathing
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loss of abdominal muscle tone, produces pronounced distension of the abdomen during inspiration
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What is the function of the scalene and sternomastoid muscles during respiration
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Elevate the rib cage
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What is the function of the trapezius muscle during respiration
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Stabilizes tehe had so that contraction of the sternomastoid does not move the head and thus dampen its action on the rib cage
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What is the function of the transversus abdominis msucle during respiration
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Compresses abdominal contents and pushes the diaphragm cephalad
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Dead Space Volume Equation
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([Alveolar PC02 - Expired PC02]/Alveolar PC02) (Tidal volume)
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Approximately what percent of residual capacity is deadspace
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5%
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Why might anatomic dead space be larger at total lung capacity
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More negative intrapleural pressure causes dilation of the bronchia nd broncjhioles
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Approximate percent of physiologic dead space
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3%
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What change on the pulmonary function graph might account for a decreased arterial P02 in a subject with a constant C02 production and constant respiratory minute volume
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Increased respiratory rate and decreased tidal volume;
Respiratory Minute Volume = Tidal Volume x Respiratory Rate; so one has to go up and one has to go down |
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What is the function of the scalene and sternomastoid muscles during respiration
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Elevate the rib cage
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What is the function of the trapezius muscle during respiration
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Stabilizes tehe had so that contraction of the sternomastoid does not move the head and thus dampen its action on the rib cage
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What is the function of the transversus abdominis msucle during respiration
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Compresses abdominal contents and pushes the diaphragm cephalad
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Dead Space Volume Equation
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([Alveolar PC02 - Expired PC02]/Alveolar PC02) (Tidal volume)
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Approximately what percent of residual capacity is deadspace
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5%
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Why might anatomic dead space be larger at total lung capacity
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More negative intrapleural pressure causes dilation of the bronchia nd broncjhioles
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Approximate percent of physiologic dead space
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3%
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What change on the pulmonary function graph might account for a decreased arterial P02 in a subject with a constant C02 production and constant respiratory minute volume
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Increased respiratory rate and decreased tidal volume;
Respiratory Minute Volume = Tidal Volume x Respiratory Rate; so one has to go up and one has to go down |
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Aspiration of amniotic fluid = useful diagnostic tool for ARDS. When ratio of lecithin to sphingomyelin is greater than 2..
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>2 incidnece of death attributable to RDS or hyaline membrane dz decreases; at ratios greater than 2 there are no deaths attributable to RDS
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Aspiration of amniotic fluid = useful diagnostic tool for ARDS. When ratio of lecithin to sphingomyelin is less than 1..
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<1 incidnece of death attributable to RDS or hyaline membrane dz increases; at a ratio of 1 there is a survival of about 10%
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Do premature infants have high or low surfactant levels
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Low; usually deficient; causes the atelectasis seen in hyaline membrane dz of the newborne
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Surfactants affects on surface tension in small alveoli vs large alveoli
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Causes surface tension exerted on small alveoli to be less than large alveoli (bc as an alveoli expands, the surfactant concentration at the surface becomes less and tension goes up
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Alveolar pressure compared to pleural pressure during inspriation and expiration
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Alveolar pressure is higher (less negative) than the intrapleural presure during inspiration and expiration
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Which compartment has the highest 02 partial pressure
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The last 25% of inspired air after it enters the nose/mouth
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What ability of the lungs helps keep a higher pressure in the lumen of the bronchiole than in the peribronchiolar space during expiration
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elastic recoil in the lungs; bronchioles do not have cartilangenous plates to help keep them patent
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Why is there an increased tendency for bronchioles to collapse during forced expiration in a pt w emphysema
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A decrease in the elasticity of the lungs; no elastic recoil to help keep bronchioles patent
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Is lung volume greater or smaller at the base
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The itnrapleural pressure at the base of the lung is less negative and thus lung volume at the base is less than in the uper portions. The smaller volume of each inferior alveolus means theyd istend more then cephalad alveoli during inspiration to increase ventilation;
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How would increased airway constriction and tidal volume affect respiratory minute work
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increase respiratory minute work;
constriction increases resistance and thus minute work; decreased compliance increases the respiratory minute work |
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How would an increased inhaled gas density affect respiratory minute work
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Increases respiratory minute work
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How would a decrease in compliance (fibrosis) affect respiratory minute work
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Increase
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What two components make up the total work performed during inspiration
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The work used to overcome elastic forces; the work used to overcome resistance
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What is the most efficient method for an asthmatic to use during respiration?
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Lower respiratory rate and higher tidal volume than the healthy subject
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Why would a climber near the everest summit have lower arterial C02 and H+ concentratoins in the arterial blood
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hypoxia at this altitude would increase ventilation
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At the end of quiet inspiration; intralveolar pressure = ?
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0 cmH20; equal to atmospheric
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Tidal volume = 400 ml
Dead space = 100 ml Breathing frequency = 10 PaC02 = 50 Pa02 = 150 Alveolar ventilation? |
Va = Vt - Vd x f = (400-100) x 10 = 3 L/min
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Tidal volume = 400 ml
Dead space = 100 ml Breathing frequency = 10 PaC02 = 50 Pa02 = 150 Oxygen tension? |
Alveolar gas equation
Pa02 = PI02 - PAC02/R = |
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PaC02 relationship to alveolar ventilation
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Inversely proportional
PaC02 = 1/Va Va = (Vt - Vd) x f |
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Approximation of alveolar gas equation
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PA02 = 150 - PAC02/.8
PAC02 = alveolar P02 R = respiratory quotient = C02 produced/02 consumed |
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A-a gradient
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PA02 - Pa02 = 10-15 mmHg
Increased A-a gradient may occur in hypoxemia; causes include shunting, V/Q mximatch, fibrosis (diffusion block) |
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How is the equal pressure point affected by increasing recoil force vs increasing intrapleural pressure
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Increasing recoil force: Towards mouth
Increasing intrapleural pressure: Towards lungs |
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FRC
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Amount of gas in each lung after expiration; increases in obstructive diseases but not in restrictive
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How does obstructive lung disease affect FRC
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Can't expel as much air out so there is more left at the end of expiration (FRC)
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How will an asthma attack affect arterial carbon dioxide tension
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Decrease bc of increased ventilation
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What can cause a decrease in 02 saturation without a decrease in 02 tension?
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CO poisoning; affects hemoglobin but not dissolved 02
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How to calculate a question that asks you for a new PaC02 based on ventilation rate
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Set current PC02 to adjusted PC02
Pa1C02 x Va1 = Pa2C02 x Va2 |
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When is the respiratory cycle is alveolar PC02 highest?
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1/3 of the way into inspiration, bc you inhale alveolar PC02 from dead space too into alveoli as you inhale, after 1/3 in new air will mix and decrease PC02
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Transection of the brainstem above the pons would affect breathing how
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No voluntary breath holding
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How is anatomical dead space changed at total l ung capacity
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It is highest at TLC bc everything dilates including bronchi
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How is lung compliance changed at total lunc capacity
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The lungs are less compliant/stiffer
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Man breathing room air has a PaC02 (alveolar) of 48 mmHg. His alveolar oxygen tension is what
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.21(760-47) - 48 = 150 - 60 = 90
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relaxed lung volume
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functional residual capacity
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Pa02 in fetus compared to mother
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PA02 is lower bc if higher affinity for 02 by fetal hemoglobin
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How do Pa02 and PC02 change during moderate aerobic exercise
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They do not change; alveolar ventilation increases to accomodate for increased demand
pH only drops and lactate increases during anaerobic exercise |
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Forces tending to remove fluid from the alveoli
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Negative interstitial fluid pressure and the osmotic pressure exerted at the alveolar membrane by ions and crystaloid molecules in the interstitial fluid.
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Factors which can increase the diffusing capacity of the lungs (volume of gas transported/min)
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Determined by the surface area, thickness of alveolar capillary interface; increases can be produced by vasodilation, optimizing the V/Q ratio, or increasing conc of Hb (polycythemia)
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How will increased arterial P02 affect Hb saturation
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Increase it
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how does age affect pulmonary compliance
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getting older = more compliant lungs (same as w emphysema)
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Why do the alveoli at the base get more air than the apex
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They are more compliant
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Why is V/Q lower at the base then the apex?
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Ventilation is 3x greater at base but flow is about 10x greater
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Absolute lung volumes
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Residual volume, functional residual capacity, total lung capacity; cant be measured by spirometry
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Why does maximum flows decrease in asthma and bronchitis
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Increased resistance
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Why does maximum flow decrease in emphysema and bronchiolitis
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Lung recoil force has decreased
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How does low lung compliance affect recoil force
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Increases the recoil force at any given volume and thus maximum flow rate at any given volume is higher than normal
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