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82 Cards in this Set
- Front
- Back
tidal volume
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volume inspired or expired with each normal breath
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inspiratory reserve volume
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volume inspired over and above TV ex. during exercise
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expiratory reserve volume
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volume that can be expired after expiration of a tidal volume
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residual volume
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volume that remains in lungs after a maximal expiration
- cannot be measured by spirometry |
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anatomic dead space
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volume of conducting pathways
approx. 150 ml |
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physiological dead space
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- volume of lungs that does NOT participate in gas exchange
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calculation of physiological dead space (Vd)
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Vd = TV x (PaCO2 - PeCO2) / PaCO2
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minute ventilation
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TV x breaths/min
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alveolar ventilation
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alveolar ventilation = (TV - Vd) x breaths/min
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inspiratory capacity
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IRC = IRV + TV
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functional residual capacity
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FRC = ERV + RV
volume remaining after a tidal volume is expired --> cannot be measured |
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vital capacity or forced vital capacity
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FVC = TV + IRV + ERV
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total lung capacity
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TLC = IRV + TV + ERV + RV
- cannot be measured by spirometry |
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forced expiratory volume (FEV1)
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volume of air that can be expired in the first second of forced maximal expiration
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normal value of FEV1/FVC
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0.80
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obstructive lung disease, such as (1), the FEV1/FVC ratio is (2)
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1 = asthma
2 = reduced |
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restrictive lung disease, such as (1), the FEV1/FVC ratio is either (2) or (3)
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1 = fibrosis
2 = increased 3 = unchanged |
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what is the most important muscle for inspiration?
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diaphragm
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which muscles are used for inspiration during exercise/respiratory distress?
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external intercostals
accessory abdominal muscles |
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muscles in quiet expiration?
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none --> passive recoil of lung tissue
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expiratory muscles used during exercise or when airway resistance is increased?
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internal intercostals
abdominal muscles |
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compliance of lungs
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describes distensibility of lungs
- inversely related to elastance AND stiffness - slope of pressure-volume curve C = V/P |
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transmural pressure = (1) pressure - (2) pressure
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1 = alveolar pressure
2 = intrapleural pressure |
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when intrapleural pressure is negative, the lungs (1) and volume (2)
when intrapleural pressure is positive, the lungs (3) and volume (4) |
1 = expand
2 = volume increases 3 = collapse 4 = volume decreases |
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hysteresis
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difference between inspiration and expiration lung pressure-volume curves
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when is lung compliance the highest?
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middle range of pressure on curve
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compliance of the lung-chest wall system is (1) than that of lungs or chest (2)
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1 = less
2 = alone |
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pneumothorax
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lungs collapse
chest wall springs forward (natural tendencies) |
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emphysema
- lung compliance is (1) and tendency of lungs to collapse is (2); tendency of lungs to collapse is (3) than tendency of chest wall to expand resulting in (4) |
1 = increased
2 = decreased 3 = less 4 = barrel-shaped chest |
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in fibrosis, lung compliance is (1) and tendency of lungs to collapse is (2); the tendency of lungs to collapse is (3) than tendency of chest wall to expand
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1 = decreased 3
2 = increased 3 = greater |
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collapsing pressure (surface tension)
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P = 2 T / r
T = surface tension r = radius |
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in absent of surfactant, small alveoli have a tendency to (1) known as (2)
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1 = collapse
2 = atelectasis |
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surfactant
- roles (2) - synthesized where? (1) - made of (3)? |
2 = decreases surface tension, increases compliance
1 = type II alveolar cells 3 = DPPC dipalmitoyl phosphatidylcholine |
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Ratio of what reflects mature lungs?
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lecithin/sphingomyelin ratio of 2:1 in amniotic fluid
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neonatal respiratory distress syndrome
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due to lack of surfactant
lungs collapse, difficulty reinflating and hypoxia |
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formula for airflow
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Q = P / R
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poiseuilles law for resistance
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R = 8 n l / (pi) r^4
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where is the major site of airway resistance?
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medium bronchi
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What causes constriction of airways? (3)
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1 = PNS
2 = irritants 3 = slow reacting substance of anaphylaxis (asthma) |
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What causes dilation of airways? (2)
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1 = SNS stimulation
2 = SNS agonists i.e. isoproterenol that act on B2 AR |
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asthma is an (1) disease, with (2) FVC and (3) FEV1 and (4) FEV1/FVC ratio; functional residual capacity is (5)
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1 = obstructive disease
2 = decreased 3 = decreased 4 = decreased 5 = increased |
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COPD is an (1) disease with (2) lung compliance; characterized by (3) FCV, (4) FEV1 and thus, (5) FEV1/FVC ratio
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1 = obstructive disease
2 = increased lung compliance 3 = decreased 4 = decreased 5 = decreased |
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fibrosis is a (1) disease with (2) lung compliance characterized by a decrease in (3); FEV1/FVC ratio is (4)
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1 = restrictive disease
2 = decreased lung compliance 3 = decrease in all lung volumes 4 = increased (normal) |
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pink puffers
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emphysema
- mild hypoxemia - maintain alveolar ventilation = normocapnia |
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blue bloaters
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bronchitis
- severe hypoxemia with cyanosis - do not maintain alveolar ventilation = hypercapnia - right ventricular failure and systemic edema |
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Dalton's law of partial pressure
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PP = total pressure x fractional conc.
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physiological shunt
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2% of systemic cardiac output bypasses pulmonary circulation making the PO2 of arterial blood slightly lower than that of alveolar air
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perfusion limited exchange
- demonstrated by (1) - gas equilibrates (2) along length of pulmonary capillary - diffusion of gas can only be increased in blood flow (3) |
1 = N20, O2 under normal conditions, CO2
2 = early 3 = increases |
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diffusion limited exchange
- demonstrated by (1) - gas (2) equilibrates along pulmonary capillary |
1 = CO, O2 under strenous exercise
2= does not equilbrate |
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subunits in fetal hemoglobin
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a2 y2
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fetal Hb has a (1) affinity for O2 than adult Hb bc 2,3BPG binds (2)
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1 = higher
2 = less tightly |
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methemoglobin
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Fe3+
does not bind O2 |
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O2 binding capacity of blood
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max amount of O2 that can be bound to Hb
- depends on Hb conc. |
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SHIFT to the RIGHT of Hb-O2 curve
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increased PCO2
increased 2, 3 BPG decreased pH increased temp |
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LEFT SHIFT of Hb-O2 curve
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HbF
CO ---> affinity of Hb for O2 is increased |
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CO (1) the O2 content of the blood
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decreases
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hypoxemia
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decrease in arterial PO2
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A-a gradient
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- used to compare causes hypoxemia
A-a gradient = alveolar PO2 - arterial PO2 |
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alveolar PO2
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alveolar PO2 = inspired Po2 - alveolar PCO2 / R
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normal A-a gradient
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is less than 10 mmHg
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Increased A-a gradient
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- if O2 does not equilibriate between alveolar and arterial blood
- diffusion defect - V/Q defect - right to left shunt |
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what is the major form of CO2 in blood?
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HCO3
- small amounts of CO2 dissolved and as carbaminohemoglobin |
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main buffer of H+ in RBCs?
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deoxyhemoglobin
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pulmonary circulation vs. systemic circulation
- pressure is (1) - resistance is (2) - CO of RV = (3) |
1 = much lower (15 mmHg)
2 = lower 3 = pulmonary blood flow |
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blood flow is lowest in the (1) of lung and highest at (2)
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1 = apex (zone 1)
2 = base (zone 3) |
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zone 1
- blood flow (1) - alveolar pressure is (2) than arterial pressure |
1 = lowest
2 = greater than --> high alveolar pressure compresses capillaries --> hemorrhage or positive pressure ventilation |
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zone 2
- blood flow (1) - alveolar pressure is (2) than arterial pressure |
1 = medium
2 = lower |
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zone 3
- blood flow (1) - arterial pressure is the (2) |
1 = highest
2 - highest |
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In contrast to other organs, in lungs, hypoxia causes (1) which redirects blood away from poorly ventilated, hypoxic regions
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1 = vasoconstriction
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right to left shunts
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ex. tetralogy of fallot
--> always decrease arterial PO2 |
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V/Q ratio
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ratio of alveolar ventilation to pulmonary blood flow
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Where is the V/Q ratio highest? (apex or base)
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apex
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apex has (1) regional arterial PO2 and (2) regional PCO2 bc gas exchange is more efficient
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1 = highest
2 = lower |
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dorsal respiratory group
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- inspiration
- generates basic rhythm of breathing |
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ventral respiratory group
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- expiration
- not active during normal quiet breathing --> only active when expiration is an active process |
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apneustic centre
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lower pons
- stimulates inspiration - deep and prolonged inspiratory gasp |
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pneumotaxic centre
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upper pons
- inhibits respiration - regulates depth and rate of breathing |
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central chemoreceptors
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- located in medulla
- sensitive to pH of CSF (decreases in pH increased breathing) |
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peripheral chemoreceptors
- location? (1) - respond preferentially to? (2) |
1 = carotid and aortic bodies
2 = decreased PO2 (<60 mmHg) |
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Hering-Breur Reflex
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receptors are stimulated by distension of lungs, the produce a reflex decrease in breathing reflex
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J (juxtacapillary) receptors
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located in alveolar walls close to capillaries --> engorgement of capillaries i.e. left heart failure causes rapid, shallow breathing
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joint and muscle receptors and breathing
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early stimulation of breathing during exercise
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