Physiology of Breathing 2 Flashcards
Main function of the lungs
Gas exchange
Other funtcions of the lungs aside from gas exchange
Heat exchange, Blood Gas Homeostasis, Phonation, Defense, Bioactive substrate metabolism
What will holding one’s breath do to blood gas pH?
Acidify
Rapid breaths will have what effect on blood gas pH?
Alkalinize
What controls breathing
Medulla Oblongata
Lung surface area
100-160m^2
How much of the cardiac output does the lungs receive?
> 95%
What do the lungs do to the peptides bradykinin and angiotensin?
Deactivate bradykinin and convert angiotensin I to angiotensin II
Non-respiratory functions of the lung
act on serotonin and norepinephrine, deactivate bradykinin, convert angiotensin I to II, remove prostaglandin residues from arachidonic acid
Boyle’s Law
P1V1 =P2V2; Temp is constant
T or F: During inspiration, pleural pressure is positive.
False. Pleural pressure is negative during inspiration. No pressure = more “freedom” to expand
Alveolar pressure is also known as ________?
Intrapulmonary pressure
T or F: The intrapleural pressure is of a more negative value than the atmospheric pressure during normal tidal breathing
True
What is the transpulmonary pressure?
Pressure difference between alveolar and intrapleural pressure
Importance of the transpulmonary pressure
It is the main force which stretches the lung and prevents its total collapse. It also determines the magnitude and direction of lung expansion
At resting position, the alveolar pressure (intrapulmonary pressure) is _______ to atmospheric pressure
Equal
Normal value for lung compliance
.2 L/cm H2O
Determinants of Lung Compliance (CRS)
Lung (elastic properties and surfactant)
Chest wall elasticity
Given that “compliance” is more of a measure of how “giving” a space is, wrt a given pressure change, what does this predict?
Extent of volume change
A stiff, non-compliant lung will require a (greater/lesser) pressure exchange for each breath?
greater
What accounts for hysteresis seen in a lung inflated with air?
Surfactant
What does the surfactant do?
Work to decrease surface tension, increasing compliance; protecting alveoli at risk of being destroyed due to surface tension
According to whose law do smaller alveoli experience higher pressure than larger alveoli?
Laplace’s law: P=2T/r; C\As illustrated by the cohesive force of surface molecules (causing surface tension) of a bubble will exert an inward force creating pressure inside. Therefore, the smaller the bubble, the more pressure inside
Source of surfactant
Type 2 Pneumocyte
Main phospholipid of surfactant
Dipalmitoyl phosphatidyl choline (DPPC)
When the alveolar surface and large and the surfactant molecule is spread apart (as in inspiration), surfactant surface tension is less/more?
Less
When a lung is being inflated from a low lung volume, is the surfactant acting a lot to reduce surface tension?
No. Much of it is in the water layer and NOT at the surface. There is no need to reduce surface tension
When is surfactant effect at its greatest?
When the molecules are completely covering the lining surface (when alveoli are small or when the lung deflates)
What are other functions of surfactants?
Expansion of lungs at birth, protects patency of airways, prevents movement of fluid to the alveolus, helps prevent pulmonary edema
Two types of work when breathing
Elastic- work on inspiration to stretch lung
Resistive- work on inspiration to bring airflow into the lung against resistance and to move the tissues
Elastic work: slow breathing ::
Resistive work: quick and shallow breaths
When a higher tidal vol but slower RR, or a lower tidal vol, and faster RR occur
Minute ventilation
High RR and flow = (Elastic/Resistive work)
High Resistive Work
Low RR, High tidal vol = (Elastic/Resistive work)
High Elastic Work
Abnormal pathology INSIDE airways manifest as wheezing during (inspi./expi)?
Expi
Abnormal pathology in EXTRATHORACIC conditions will manifest as a wheeze during (inspi/expi)?
Inspi
