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42 Cards in this Set

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

This allows the lung to divert blood away from poorly ventilated areas and to better areas.
Describe the V, Q, V/Q, arterial Po2 at the apex and base.
Apex = lowest blood blood, lower ventilation, highest V/Q, increased Po2.

Base = greatest blood flow, smallest V/Q, decreased PO2.
Describe central control of breathing.
Medulla - responds to pH of CSF (CO2)
Describe peripheral chemoreceptors involved in breathing.
Carotid bodies
Aortic bodies.
Respond to oxygen, CO2 and pH.
Drug to treat respiratory alkalosis
Acetazolamide, a carbonic anhydrase inhibitor. Causes you to dump out HCO3.
Calc PA02
= PI02 - PACO2/.8
=150 - alveolar PCO@/.8