Mechanics of Resp part 2 - Quiz 2 Flashcards Preview

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Flashcards in Mechanics of Resp part 2 - Quiz 2 Deck (17):

What conditions might cause a reduced lung compliance?

Higher or Lower lung volumes
Higher expansion pressure,
venous congestion,
alveolar edema,
atelectasis & fibrosis


What conditions might cause an increased lung compliance?

Advanced Age
emphysema (due to alteration of elastic fibers)


How much of the elastic forces of the lung is created by the Surface Air-Fluid Interface?

2/3 of totla elastic force


Why is surfactant important?

elastic force (keeps alveoli open)
Breaks surface tension of H2O (makes water wetter)


What is surfactant and what is it made by?

It is a synthesized fatty-acid product of Type II Pneumocytes
Has hydrophobic and hydrophyllic heads


What is Surface Tension Elastic Forces in relation to the lung? What stops it from happening?

The net effect on the lung to sumultaneously attempt to collapse alveoli by water tension.
-Surfactant stops process


Name 3 functions of Surfactant.

1. Lowers surface tension of alveoli & lung
2. Promotes stability of alveoli
3. Prevents transudation of fluid into alveoli


What are the equations for Minute Ventilation (MV) and alveolar ventilation (VA)?

- MV = Vt x resp
- VA = MV x 70%


What is Anatomic Dead Space?

Areas of the airway that are ventilated but not perfused


How do you calculate Dead Space?

2ml/kg of Ideal Body Weight or weight in pounds
Vt = VA + Vd


What is Wasted Ventiliation and what could cause it?

areas of the lung that are ventilated and are normally perfused but has a blockage of blood flow causing a V/Q mismatch.
Could be caused by Pulmonary Embolism


Describe Poiseuille Law

Describes resistance to flow through a tube.
Pressure increases proportional to flow rate and gas viscosity.
Smaller airway radius and longer distances increase flow resistance.
**reducing radius by 16% double the Resistance
** reducing radius by 50% increases resistance 16-fold


Ohm' s Law equation

P = F x R where P=pressure, F=flow, R=resistance


What can cause turbulent flow?

- higher flow rates or air velocity
- Local eddies form at sides of airway and stream lines of flow become disorganized
- pressure no longer proportional to flow
- Increases in density, velocity, and airway resistance make turbulence more probable.


What is the chief site of airway resistance?

Medium-sized bronchi


Where does most pressure in the airways decrease?

Most pressure drops occur at SEVENTH division


What is the work of breathing equation?

W = P x V
W = work of breathing
P = Pressure
V = Volume