West Pulmonary Book (end of chapter summary notes) Flashcards
Tidbits from the summaries and key points for the first few chapters (41 cards)
What two zones are the airways divided into?
- conducting zone
- respiratory zone
The volume of the anatomic dead space is about how much?
150 mL
The volume of the alveolar region is about how many liters?
2.5 - 3 L
Gas movement in the alveolar region is done chiefly by ______.
diffusion
The approximate surface area of the alveoli is about how much?
50 - 100 meters squared
In the alveolar ducts, the predominant mode of gas flow is _______ rather than _______.
- diffusion
- convection
When you take a maximal inspiration followed by a maximal expiration, the exhaled volume is called what?
vital capacity
The gas that remains in the lungs after maximal expiration is known as what?
residual volume
The volume of gas in the lung after a normal expiration is known as what?
functional residual capacity
The amount inspired and expired during normal ventilation is called what?
tidal volume
How do you calculate total ventilation?
tidal volume x respiratory frequency
With normal ventilation, which areas ventilate better, the upper or lower areas?
the lower areas ventilate better than the upper areas
(regardless of what position the patient is in (supine, lateral, etc) the dependent part of the lung will have better ventilation, d/t the effects of gravity)
Which lung volumes cannot be measured with a simple spirometer?
- total lung capacity
- functional residual capacity
- residual volume
Is the concentration of CO2 (and therefore its partial pressure) in alveolar gas and arterial blood directly or inversely related to the alveolar ventilation?
inversely related
Fick’s Law of diffusion states that the diffusion rate of a gas is directly proportional to what (3 things), and inversely proportional to what (1 thing)?
directly proportional:
- partial pressure gradient
- membrane area
- solubility of the gas
inversely proportional:
1. membrane thickness
The rate of transfer of a gas is proportional to a diffusion constant, which depends on the properties of the tissue and the particular gas. What is directly and inversely proportional to this constant?
- directly proportional to the solubility of the gas
- inversely proportional to the square root of the molecular weight
The diffusion process can be challenged by what 3 things?
- exercise (d/t increased blood transit time through the pulm capillaries and less time for exchange)
- alveolar hypoxia (not enough O2 hopping on the RBCs)
- thickening membrane (can’t get through)
In normal lungs, when pulmonary vascular pressures are increased (ie with exercise), the pulmonary vascular resistance is decreased by what two mechanisms?
- recruitment (opening of previously closed vessels)
- distention (increased in caliber of the vessels)
Define hypoxic pulmonary vasoconstriction.
the contraction of smooth muscle in the walls of the small pulmonary arterioles in hypoxic regions of the lungs
At what point in one’s life is the release of hypoxic pulmonary vasoconstriction critical?
at birth in the transition from placental to air breathing
for knowledge!
What is the approx. ratio of the pressures in the pulmonary circulation to that of the systemic circulation?
1:10
pulm ~ 10 mmHg, systemic ~ 100 mmHg
If capillary pressure is less than alveolar pressure at the top of the lung, what happens to the capillaries?
they collapse
Fluid movement across the capillary endothelium is governed by what concept?
the Starling equilibrium
basically has to do with the differences in hydrostatic and osmotic pressures in the vasculature and the interstitium
In zone 2 of the lung, blood flow is determined by _______ _______ minus _______ _______.
arterial pressure minus alveolar pressure
