Respiration lecture 7 Flashcards
What can the respiratory system be regarded as?
a pump with elastic and flow-resistive properties
What happens to the lungs and Ppl at rest?
The lungs are at FRC and the Ppl in negative due to the opposite forces acting on the lungs and chest wall.
What happens to the diaphragm and chest wall during inspiration?
the diagram contracts and the chest wall is pulled open
This creates a more negative Ppl that causes expansion of the lungs
During inspiration, flow is __
Negative
During expiration, flow is __
Positive
What is the formula for flow of breath?
F= (Palv-Patm)/R
The resting position of the lungs is below…
residual volume
As the lungs are pulled further away from their resting position, what happens to Ppl?
it becomes even more subatmospheric
(inspiration) As the volume of the lungs is ____, gas in the lungs is ____, Palv drops _____ atmospheric pressure.
increased
decompressed
below (Palv>Patm)
What generates air flow to the lungs during inspiration?
The negative pressure gradient between the alveoli and the atmosphere was created: during inspiration, Palv<Patm, the air will go from the atmosphere into the alveoli.
What happens to the pressure gradient and the air flow as inspiration proceeds?
the pressure gradient and the airflow gradually decrease
Why does air flow stop at the end of inspiration?
because Palv is equal to Patm (no more pressure gradient)
During expiration, the diaphragm _____, elastic recoil of the respiratory system ____ the gas in the lungs, and Palv ____.
relaxes
compresses
increases
What happens to the pressure gradient between the atmosphere and the lungs during expiration?
It becomes a positive (reversed), and the air in the lungs in pushed out into the atmosphere
What happens to Ppl as lung volume decreases during expiration?
is slowly returns to resting levels
What is the air flow, Palv and Ppl at the end of expiration?
Air flow: 0
Palv: 0
Ppl: back to negative resting pressure
What does the time course of changes in pleural pressure during inspiration and expiration depend on?
the contraction of respiratory muscles and airway resistance
What must occur in order to have gas flow through the airways?
Pao (oral pressure) must be different from Palv
What is the formula for the resistance in the airways ?
Raw = (Palv-Pao)/flow
A ___ diameter airway can carry a ___ flow for a given pressure difference.
large
large
What is airway resistance related to?
to airway calibre
What happens to airway resistance during asthma?
The resistance increases due to different factors and makes it difficult to breath
When a subject inspires to TLC and exhales to RV, during expiration, flow ___ very rapidly to a ___ value and then ___ over the rest of expiration.
rises
high
declines
Why is the descending portion of the flow-volume curve independent of effort?
because of the compression of the intrathoracic pressure
With resistance, the Palv pressure decreases along the airway and at some point goes lower than the Ppl pressure. At that point, the airways are squeezed and air flow can’t go any faster even with effort
What are the values of airway pressure and intrapleural pressure before inspiration?
-5 (negative)
What happens to the airway pressure and intrapleural pressure during inspiration?
Airway pressure becomes more negative as well as the Ppl pressure
What are the values of airway pressure and airway transmural pressure at the end of inspiration?
Ppl is more negative than usual ( -8), whereas the airways go back to zero Meaning that Ptm = Paw-Ppl = 0-(-8) = 8 is positive to keep the airways open, even without flow
What happens to the alveolar pressure and intrapleural pressure during forced expiration?
the Ppl become positive because of the force exerted by the muscles but still remain lower than the airway pressure
The airway pressure is very high but decreases as it travels because of resistance: at some point, it goes lower than the Ppl pressure.
Why is there a positive pressure tending to close the airways during forced expiration?
When the airway pressure gets lower than the Ppl pressure, it squeezes the airways
Why does the positive pressure decrease when moving out of the lungs during forced expiration?
because of resistance
What kind of recoil is found in restrictive diseases like pulmonary fibrosis?
lung elastic recoil is increased, making the lungs stiffer and harder to expand. This decreases lung compliance, requiring greater effort to inhale and resulting in smaller lung volumes (↓TLC, ↓FVC, ↓RV).
What happens to the maximum flow rate and maximum volume exhaled in restrictive diseases?
They are both reduced
What happens to the flow rate in obstructive diseases?
It is a very low flow rate
What kind of recoil is found in obstructive diseases like emphysema?
There is minimal recoil because the alveoli are easily squeezed (floppy)
What are the 7 steps of events during inspiration?
The diaphragm and intercostal muscles contract
Thoracic cage expands
Intrapleural pressure becomes more negative
Transpulmonary pressure increases (gradient created)
Lungs expand
Alveolar pressure becomes subatmospheric
Air flows into the alveoli
What are the 8 steps of events during expiration?
The diaphragm and external intercostals relax
Chest wall moves inwards
Intrapleural pressure goes to pre-inspiratory value
Transpulmonary pressure goes to pre-inspiratory value
Lung recoil to pre-inspiratory volume
Air in the lungs is compressed
Alveolar pressure becomes greater than atm pressure
Aif lows out of the lungs
What increases proportionally when exercise starts?
Minute ventilation: frequency and tidal volume
What happens to tidal volume during exercise?
It increases proportionally until it plateaus at very high exercises levels
What happens to ventilatory rates during hard exercise?
Breathing frequency keeps increasing proportionally to exercise levels
Because of the increased breathing frequency, inspiratory and expiratory times ___ during progressive exercise but expiratory times fall relatively __ than inspiratory time.
decrease
more
Which flow rate increases more during exercise?
exhale vs inhale
The flow rate of expiration needs to change more than the flow rate for inspiration since they will reach about the same rate but start with the expiration being longer
In both untrained and trained subjects, what increases linearly with metabolic rate?
Minutes ventilation
How much does minute ventilation increase in both trained and untrained subjects?
increases to about 50-65%
Minute ventilation ___ at a rate disproportionately ___ than the change in VO2.
increases
greater
An effect of endurance training is to ___ the ventilatory inflection point.
delay
How much can resting values of minute ventilation increase during exercise in a fit individual?
35 fold
How much can resting values of cardiac output increase during exercise in a fit individual?
5-6 fold
Which increases more during exercise; minute ventilation or perfusion?
minute ventilation
What is one of the reasons why ventilation is not believed to limit aerobic performance?
There is more surface area for gas exchange in the lungs than in the blood
What is the alveolar surface area?
50 m^2
What is the average blood volume?
5L
What percentage of blood volume is in the pulmonary system at any one time during maximal exercise?
4%
What limits the ventilatory response during exercise?
The dead space limits the gas exchanges possible during exercise ventilation
What is asthma?
A constriction of the airways due to inflammation, cold, exercise, etc.
What are the symptoms of asthma?
Difficulty breathing, having good airflow due to increased resistance
What is emphysema?
Emphysema is a chronic lung condition where the air sacs (alveoli) in the lungs are damaged, leading to difficulty breathing and reduced oxygen intake.
What happens to airways in people with emphysema?
the airways become weakened and lose their elasticity. The walls of the air sacs (alveoli) break down, causing them to enlarge and reducing the surface area for gas exchange.This leads to airflow obstruction and difficulty exhaling air, making it harder to breathe.
What happens to the lungs during emphysema?
the lungs lose their ability to expand and contract efficiently, making breathing increasingly difficult.
What is fibrosis?
the thickening and scarring of connective tissue, this scarring can reduce lung function
ALVEOLAR PRESSURE CHANGES BECAUSE OF:
thoracic volume changes
