HY Respiratory Phys + Karius review Flashcards
Ratio of what molecules produced by the lungs is a marker for lung maturity?
Lecithin:sphingomyelin ratio. Usually greater than 2
Diameter of airways depends upon the balance between what two molecules produced in the lung
prostaglandins (bronchodilation) and Histamine (bronchoconstriction)
Which molecule is produced by the lung such that when inhibited produces a build up product that causes a dry cough
Angiotensin Converting enzyme
What important coagulation cascade cofactor is produced in the lung?
Kallikrein
What is residual volume (RV)?
volume that remains in lungs after a maximal expiration
What is tidal volume (TV)?
Volume inspired with each normal breath
What is inspiratory reserve volume (IRV)?
volume that can be inspired over and above the tidal volume. Used during exercise
What is expiratory reserve volume (ERV)?
Air that can still be breathed out after normal expiration
What is inspiratory capacity?
IRV + TV
What is functional residual capacity
RV + ERV. Volume of gas in lungs after normal expiration; includes RV, cannot be measured on spirometry
What is vital capacity?
TV + IRV + ERV = max volume of gas that can be expired after a maximal inspiration
What is total lung capacity?
IRV + TV + ERV + RV = volume of gas present in lungs after a maximal inspiration. (notice it includes RV which cannot be measured by spirometry)
Differentiate between anatomic vs physiologic dead space and alveolar dead space.
Dead space is area of the respiratory system that do not participate in gas exchange. Anatomic dead space = conducting zones of respiratory system. Physiologic dead space = anatomic dead space in a non diseased state; in a disease state physiologic dead space = anatomic dead space + functional (alveolar) dead space. Alveolar dead space = alveoli which receive ventilation but are poorly perfused (apex of lung biggest contributor to alveolar dead space)
How is physiologic dead space calculated?
Vd/Vt = (PaCO2 - PeCO2) / PaCO2
Vd = phys dead space+anatomic dead space + alveolar dead Vt = Tidal volume PaCO2 = arterial PCO2 PeCO2 = expired air PCO2
Taco, Paco, Peco, Paco (refers to orer of variable )
What is minute ventilation and how is it calculated?
Total volume of gas entering lungs per minute
Ve = VT x RR
What is alveolar ventilation and how is it calculated?
volume of gas per unit time that reaches alveoli.
Va = (Vt-Vd) x RR
Normal values: Vt = 500/breath; Vd = 150 mL/breath; RR = 12-20
Elastic recoil is the tendency of lungs to collapse inward and chest wall to spring outward. These two recoils equals to zero at what point?
FRC (functional residual capacity)
At FRC, indicate at what level of each of these factors are in:
A. Airway and alveolar pressure
B. Intrapelural pressure
C. PVR (pulmonary vascular resistance)
A. 0
B. Negative value
C. At minimum resistance
What is lung compliance defined as?
Change in lung volume for a change in pressure; expressed as deltaV/deltaP and is inversely proportional = lung easier to full at high compliance; lung harder to fill at low compliance
What are some diseased states in which lung compliance:
A. decreased
B. Increased
A. pulmonary fibrosis, pneumonia, pulmonary edema
B. emphysema, normal aging
What is hysteresis?
The combo of inhalation and deflation curve of pressure volume curve). The transpulmonary pressure vs Volume curve of inhalation is different from the Pressure vs Volume curve of exhalation, the difference being described as hysteresis. Lung volume at any given pressure during inhalation is less than the lung volume at any given pressure during exhalation.
with decreased O2 explain the difference between pulmonary blood flow and systemic blood flow
Decreased O2 levels leads to vasodilation of peripheral arteries thus increased blood flow and the opposite is true for pulmonary circulation: with decrease O2 –> vasoconstriction –> decreased flow –> shunting of blood from poorly ventilated areas to more to well ventilated areas. In sum: increase PaO2 blood flow increase in the lungs, but decrease blood flow systemically
Differentiate difference pulmonary circulation and systemic circulation
Pulmonary = low pressure system 24/12 mmHg Systemic = high pressure system 120/80 mmHg
Gases must diffuse from air to blood. The rate of diffusion depends on what factors?
- Pressure difference (air - blood)
- area of alveoli for diffusion
- Thickness of alveolar tissue