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
What is dead space?
it is some inspired air never contributed to gas exchange, this air fills the conducting respiratory passageways, if TV is 500ml, only 350ml is actually involved in alveolar ventilation
Ventilation equation?
pulmonary/minute ventilation (ml/min) = tidal volume (ml/breath) x respiratory rate (breaths/mins)
Alveolar ventilation?
TV - dead space (ml/breath) x respiratory rate (breaths/min)
What affects alveolar ventilation?
Depth of breathing affects alveolar ventilation more than respiratory rate
What is spirometry?
it measures respiratory function (lung volumes) and monitors progression of certain respiratory diseases, it does not provide a specific diagnosis but can distinguish between obstructive and restrictive lung diseases
What do volume lopp and vitagraph provide?
Provides additional information related to the rate at which gas moves in and out of the lungs
What is FEV1?
Forced expiratory volume is the amount of air exhaled in the first second during a force rapid exhale after a deep breath (forced vital capacity FVC) - FEV1 /FVC ratio
Define a obstructive lung disease? and draw
Increased airway resistance: chronic bronchitis, athsma and emphysema
Define an restrictive lung disease and draw
Restrictive lung disease = reduced lung compliance - tuberculosis, lung fibrosis (asbestos)
What is gas exchange?
Gas exchange: O2 and CO2 need to move between the lungs and other body cells - it’s transported in blood and exchanged by passive diffusion
What is the partial pressure gradient?
The patial pressure gradient difference in particual pressure between blood and surrounding structures (Alveolar air and pulmonary capillary blood, systemic capillary blood and surrounding cells –> gases move from high to low)
What is partial pressure?
Partial pressure (P gas) is the pressure exerted by a particular gas relative to the total gas pressure (applies to gasses dissolved in liquid)
What factors influence gas exchange by diffusion?
Thickness and SA of exchange membrane: shorter distance and greater SA for diffusion = greater rate of diffusion = greater rate of diffusion
What is ventilation-perfusion coupling? DRAW DIAGRAM
Ventilation perfusion coupling is a close match between ventilation (amount of gas reaching alveoli) and perfusion (blood flow in pulmonary capillaries)
