Respiratory physiology lab Flashcards
Tidal volume
The amount of air inspired or expired during normal, quiet respiration
Inspiratory reserve volume
The amount of air which can be forcefully inspired above and beyond that taken in during a normal inspiration.
Expiratory reserve volume
The maximal amount of air which can be forcefully expired following a normal expiration.
Residual volume
The amount of air which remains trapped in the lungs after a maximal expiratory effort
Total lung capacity
The total amount of air the lungs can contain–the sum of all four volumes.
Vital capacity
The maximal amount of air that can be forcefully expired after a maximum inspiration.
Functional residual capacity
The amount of air remaining in the lungs after a normal expiration
Inspiratory capacity
The maximal amount of air which can be inspired after a normal expiration
How much smaller are volumes or capacities in females compared to males?
20-25% smaller
Capacities
There are 4 capacities that are combinations of two or more volumes
Spirometer
An instrument used to measure respiratory volumes
Respiratory minute volume
You get this value by multiplying tidal volume and respiratory rate per minute
Heymer test of respiratory reserve
In this test the subject takes five deep breaths and then holds their breath as long as possible after the last inspiration. The breath-holding time gives an indication of the person’s functional respiratory reserve and efficiency of their respiratory system. The test is performed 2-3 times and the average is taken.
Normal values for the Heymer test
Normal values for men are 50-70 seconds and for women, 50-60 seconds.
Why are pulmonary measurements important?
Changes is pulmonary measures are caused either by disease or recovery from a disease. For example, the vital capacity is found to decrease in right heart disease. This is due to blood congestion in the lung capillaries, which in turn leads to pulmonary edema and a decrease in VC. As the person recovers, their heart becomes stronger, pulmonary congestion and edema decrease, and the VC increases. The vital capacity also decreases in paralytic polio due to partial paralysis of respiratory muscles, and in various other respiratory diseases
Nonogram
Graph that predicts forced expiratory volume and vital capacity in males or females when given their height and age
How is tidal volume measured?
Tidal volume can be measured by exhaling through a tube connected to a dry gas meter. This meter measures the volume of gas that passes through it (similar to the natural gas meter in your home) and keeps a cumulative total. One can calculate tidal volume by dividing the total air exhaled by the number of breaths made over the collection period.
How is metabolic rate measured?
Metabolic rate (measured in ml O2 consumed/min) can be determined by calculating the difference between in the percentage of O2 in inhaled air (20.95%) and the percentage of O2 in exhaled air (measured by the oxygen analyzer), and then multiplying this percentage difference by the volume of air breathed during a measured time span (measured by the dry gas meter)
The rate of oxygen consumption is equal to (2)
- The rate at which the respiratory exchange surface of the lungs obtains oxygen from the environment
- The rate at which oxygen is extracted from the blood going through the capillaries
How are the 2 factors that influence the rate of oxygen consumption measured?
Both can be calculated by measuring the flow (ml/min) of the medium (air or blood) and multiplying by the amount of oxygen that is extracted per ml of medium that passes the exchange surface.
Minute volume
Flow of air in the respiratory system
Cardiac output
The flow of blood in the circulatory system
Concentrations of oxygen in the inspired air and exhaled air definition
The amounts of oxygen per ml of medium entering and leaving the exchange surfaces in the respiratory system.
Concentrations of oxygen in the systemic arterial blood and the systemic venous blood definition
The amounts of oxygen per ml of medium entering and leaving the exchange surfaces in the circulatory system
