Module 1 Lecture 6 Flashcards
What is the atmospheric pressure at sea level?
The atmospheric pressure at sea level is 760 mmHg
Before inspiration?
Equilibrated - no net movement of air, the preinspiratory size of lungs (760)
During inspiration?
Size of the thorax on the contraction of inspiratory muscles (expands), the size of the lungs as they are stretched to fill the expanded thorax
Expiration?
Size of thorax - smaller, relaxation of the inspiratory muscle, size of the lungs as they recoil? bigger?
What is airflow?
airflow is the volume of air flowing through the lungs at a given point
What is airflow directionally proportional to?
Airflow is directionally proportional to the pressure gradient between external atmospheric and alveoli and inversely proportional to resistance airway passages
What is the formula for airflow?
F ∝ pressure gradient/resistance
What has the biggest influence on airflow?
During normal quiet breathing, pressure gradient has the biggest influence on air flow
Why are liquid molecules strongly attached to each other?
Liquid molecules are strongly attached to each other, it creates tension called surface tension
What is surfactant?
It is a detergent-like mixture of lipids and proteins decreases in water cohesiveness
What does detergent do to water?
surfactant reduces attraction between water molecules, it reduces surface tension of alveolar fluid and reduces tendency to recoli/alveolar collapse
Why are premature babies at risk?
Premature babies are at risk because they lack sufficient surfactant and alvoli which may collapse between breathes
How does a change in lung volume occur?
Change in lung volume occurs with a change in transpulmonary pressure, the greater the lung compliance, the greater the expansion at any given transpulmonary pressure.
How is lung compliance determined?
Lung compliance is determined largely by two factors. Distensibility of lung tissue ( increase in lung compliance) alveolar surface tension (decrease in lung compliance)
Note
Lung distensibility is generally high and surfactant keeps alveolar surface tension low, healthy lungs have a high compliance for efficient ventilation - thoracic respiratory compliance is also affected by thoracic wall compliance
Draw and lable the respiratory volumes
–
Define tidal volume
It is the amount of air that moves in and out during normal quiet breathing
Define inspiratory reserve
it is the amount of air that can be breathed in forcibly beyond TV
Define expiratory reserve
is the amount of air that can be breathed out forcibly beyond TV
Define residual volume
Amount of air remaining after forced expiration helps to keep alveoli open
What is inspiratory capacity?
Inspiratory capacity is the total amount of air that can be inspired after normal tidal volume expiration -> TV and IRV
What is functional residual capacity?
The functional residual capacity is the amount of air remaining in lungs after a normal tidal volume expiration –> RV and ERV
What is vital capacity?
It is the amount of exchangeable air –> TV, IRV and ERV
What is totoal lung capity?
Total lung capacity is the sum of all lung volumes