Pulmonary and Alveolar Ventilation Flashcards
What is Minute Ventilation (Vl)
The volume of air passing into or out of the lungs per minute
What is the Tidal Volume (VT)
The volume of air that is moved between either inspiration or expiration
What is the approximate resting tidal volume
0.5L/breath
What is Inspiratory reserve volume (IRV)
The maximum volume of air inspired above the tidal volume
Usually 2-3L > TV
What is the Expiratory reserve volume (ERV)
The maximum volume of air expired after the tidal volume expiration
Usually 1-1.5L > TV
What is the Vital Capacity (VC)
This is the total amount of air that can be moved in one breath from full inspiration to full expiration
What equation can be formed using IRV, VC, TV and ERV to measure total volume of exhaled air from maximal inspiration to maximal expiration
VC = TV + IRV + ERV
What is the Functional Residual Capacity (FRC)
This is the resting volume of the lung (usually like 3L)
What is the residual volume of the lungs
This is the volume left in the lungs after you breathe out as hard as possible.
What are some factors that determine the static volumes of the lungs
- Anatomy (size)
- Elasticity of lungs and chest wall
- Strength of respiratory muscles
What is spirometry a measure of
A measure of the amount of and/or speed of air that can be inhaled
What can Rolling Seal Water Filled spirometers measure
Tidal Volume
Vital Capacity
Inspiratory and Expiratory reserve Volumes
What can a turbine respirometer measure
Forced Expiratory Volume in one second
Peak Expiratory Flow (PEFR)
Why can’t RV and FRC be measured
They cannot be breathed out
What methods can be used to measure the RV or FRC
Helium Dilution
Bag containing known volume of oxygen
How does a rolling seal water filled spirometer work
closed space and subject breathes into it and movements are recorded as changes in lung volume on moving chart
What 3 pressures are responsible for pulmonary ventilation
Atmospheric
Intra-alveolar
Intrapleural
Define atmospheric, intra-alveolar and intrapleural pressure
Atmospheric - pressure in the air outside the body
Intra-alveolar - Pressure inside the alveoli of the lungs
Intrapleural - Pressure within the pleural cavity
Describe the pressure changes during breathing
Start of inspiration intra alveolar and pleural pressures decrease
Gas flows in and lung volume increases
Airflow stops when intraa-alveolar and atmospheric become equal
Exhalation = diaphragm moves up, intrapleural increases (less neg.) alveolar becomes positive and air flows out of lung
What is anatomical dead space in the upper respiratory tract and lungs
System of tubes connecting alveoli to atmosphere doesn’t do gas exchange so is dead space
Anatomical dead space is the volume of air in the mouth, pharynx, trachea and bronchi up to the terminal bronchioles
What is alveolar dead space
shows only with age or disease and is when alveoli have insufficient blood supply to act as effective respiratory membranes
what is physiological dead space
Anatomic + Alveolar dead space
Why is high frequency artificial respiration used in trauma victims
To avoid excessive movements of the chest wall.
Adequate alveolar ventilation can occur with small tidal volumes as long as frequency is high
When measuring alveolar ventilation in mL/min what equation is needed
(tidal volume - Anatomical dead space) x respiratory rate
What is the equation for respiratory exhchange ratio
Ratio of CO2 output divided by O2 uptake
given symbol “R”
What values of Respiratory exchange ratios can indicate carbohydrate and fat use
around 1 = carbs
around 0.7 = fats
Why can the respiratory exchange ratios indicate which fuel is being used
Ratio depends on oxygen already in molecule being oxidised, the more already in the molecule the less has to be brought in.
Name two factors than can changes respiratory quotient (RQ), which is basically respiratory exchange ratio
Exercise - Lactic acid enters blood, forms carbonic acid with bicarbonate and frees lots of CO2. RQ can exceed 2
Diabetics - shows low RQ due to poor metabolism of carbs and increased metabolism of fats.
