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42 Cards in this Set
- Front
- Back
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How to calc A-a gradient.
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1. Determine A by
PAoxygen = %O2(713) - arterial PCO2/.8 2. A-a 3. Normal = 5;30 =pathological. |
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What does an elevated A-a gradient indicate?
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Tells you problem is in the lung itself.
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4 condiitons associated with increased A-a gradient
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1. ventilation defect.
2. perfusion defect 3. diffusion defect 4. R to L cardiac shunt. |
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3 causes of hypoxemia with normal A-a gradient:
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1. Depressed respiratory center
2. Upper airway obstructionl 3. Dysfunction of muscles of respiration. |
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Clinical triad associated with nasal polyps
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1. NSAIDS
2. asthma 3. nasal polyps |
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What genetic disorder is associated with nasal polyps?
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cystic fibrosis
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2 risk factorsw for laryngeal carcinoma
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Smoking & alcohol (synergism)
(squamous cell) Usually affects true vocal cords. |
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3 component of surfactant
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1. lecithin
2. phosphatidylcholine 3. phosphatidylglycerol |
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When is surfactant first made?
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28th week.
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What makes surfacant and where is it stores?
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Type II pneumocytes
Sotred in lamellar bodies. |
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3 risk factors for decreased surfacant
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prematurity
maternal diabetes C-section (d/t lack of cortisol increase) |
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Drug to increased surfactant
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Cortisol, TH, prolactin
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Calc for dead space
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=tidal volume * (PaCO2-PEC02)/PaCO2
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calc for alveolar ventilation
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= tital volume - dead space (RR)
where dead space is tidal volume * PaCO2 - PECO2/PaCO2 |
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What is the effect of restrictive lung disease on FEV1 and FVC?
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both are reduced.
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What is the effect of obstructive lung disease on FEV1 and FVC?
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FEV1 is reduced more than FVC, so FEV1/FVC is decreased.
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2 muscles of inspiration
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1. diaphragm
2.external intercostals and accessory muscles (only during exercise) |
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Muscles of expiration
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Normally passive. During exercise,
1. Abdominal muscles 2. Internal intercostals |
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How is compliance related to the pressure-volume curve?
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Is the slope.
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What is the effect of restrictive and obstructive disease on FRC?
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Increases with restrictive.
vice versa. This allos the opposing forces to balance. |
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How is collapsing pressure related to surface tension and radius?
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P = 2T/R
so small alveoli have a greater tendency to collapse. |
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What is a mature lecithin:sphingomyeli ratio?
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2:1
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equation for flow
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Change in P = Q*R
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Equation for airway resistancw
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Poiseuille's law:
Resistance = 8(viscocity)(length) divided by pie(radius to the 4th power) |
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How does sympathic stimulation affect airways? via what receptor?
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Dilate.
B2. |
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Which airways offer the highest resistance?
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Medium-sized bronchi.
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During expiration, intrapleural pressure becomes______ negative (more or less)?
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More. (Elastic recoil of lungs is even greater)
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During expiration, alveolar pressures becomes______than atmospheric pressure?
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greater.
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How is calc partial pressure of oxygen in inspired air?
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=760 * .21 = 160 mmHg
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In what state(ferrous or ferric) does iron bind O2?
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Ferrous (Fe+2) binds oxygen.
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Why does fetal hemoglobin have a higher O2 affinity?
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2-3 DPG is bound less avidly.
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Calc for oxygen content:
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=(oxygen binding capacity * % saturation) + dissolved oxygen
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2 effects of carbon monoxide on oxygen.
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1. Displaces oxygen on hemoglobin. (decreases oxygen content in blood)
2. Left shift. (hemoglobin doesn't want to let go of the oxygen is has) |
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In what form is CO2 tranported in the lungs?
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HCO3-
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How does CO2 enter & leave RBCs?
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Enters as CO2 which is converted to H2CO3 by carbonic anhydrase. Then dissociates and HCO3- leaves/ Cl- enters.
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How do pulmonary pressures compare to systemic circulation pressures?
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Pulmonary pressures are much lower.
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How does hypoxia affect lung blood flow? blood flow in other organs?
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Lung: hypoxia = vasoconstriction.
Other tissues: =vasodilation. This allows the lung to divert blood away from poorly ventilated areas and to better areas. |
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Describe the V, Q, V/Q, arterial Po2 at the apex and base.
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Apex = lowest blood blood, lower ventilation, highest V/Q, increased Po2.
Base = greatest blood flow, smallest V/Q, decreased PO2. |
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Describe central control of breathing.
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Medulla - responds to pH of CSF (CO2)
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Describe peripheral chemoreceptors involved in breathing.
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Carotid bodies
Aortic bodies. Respond to oxygen, CO2 and pH. |
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Drug to treat respiratory alkalosis
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Acetazolamide, a carbonic anhydrase inhibitor. Causes you to dump out HCO3.
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Calc PA02
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= PI02 - PACO2/.8
=150 - alveolar PCO@/.8 |
