L18 Flashcards
What is pulmonary ventilation?
Inspiration and expiration of air between atmosphere and lungs
What is EXTERNAL respiration?
- Exchange of gases that takes pplace in the lungs
What is internal respiration?
Exchange of gases that takes place at tissues
What is Boyles law?
When temp of GAS is constant, pressure of a gas varies INVERSELY, (as vol increases pressure decreases and viceversa)
Can you exaplain airflow exchange using the actual atmospheric pressures. (760mmHg ATM)
- Lung expand during inspiration, Volume increases hence pressure in lungs drops to 759, gas moves from a high level in the ATmophere to low pressure in lungs
- Lung relax during expiration, lung volume decreases, pressure increases to 761 mmHg, air flows from lungs into atmosphere down pressure gradient
What is intrapleural pressure?
-What is its pressure in relation to atmosphere and intrapulmonary pressure
-How is it created?
- it is the pressure within the pleural cavity
- it is always negative in relation to both atmospheric and intrapulmonary pressure
- it is created by the elastic recoil of the lungs
What are the RESISTANCE forces to overcome for BREATHING?(4)
1)lungs compliance:
- Elastic recoil of the lungs during inspiration
- Mobility of the chest wall
- SURFACE tension
-2)Airways resistance
What is the formula to calculate COMPLIANCE ?
Change in pressure
A patient inhales 500 ml of air on a spirometer
intrapleural pressure before inspiartion was -5 cmH20, at the end of inspiration it was -8 cmh20,
What is the compliance?
change in vol in L = 0.5
Change in pressure = (-5–8)
0.5/3 = 0.1667 L/cm H20
What does the LAPLACE’S law describe?
it describes the relationship between Pressure, surface tension and alveolar radius
What is the formula for the relationship bw pressure, surface tension and alveolar radius?
P= 2T
—
r
What is SURFACTANT important in relation to LAPLACE’S law?
because it reduces TENSION (T in the part of the equation)
EQUALIZING pressure difference between small and large alveoli!
How does SURACTANT help maintain a uniform alveolar size?(4)
- More concentrated in smaller alveoli
- Reduces surface tension more in smaller alveoli so it helps equalize pressure in-between different sized alveoli (Laplace’s law)
- Makes it easier to inflate smaller alveoli
- Reduces work needed to expand each lung
What is neonatal respiratory stress syndrome?
- Premature babies born with LACK OF SURFACTANT secretion
decreases COMPLIANCE of the lungs - Alveoli collapse on exhalation
- Makes it difficult to inflate lungs
- 50% die without rapid treatment
Air way resistance is mainly affected by what?
radius
Airways resistance is mainly affected by the radius, as radius decrease airway resistance increases.
Moving down the respiratory system, airway radius decreases significantly, however RESISTANCE decreases instead of increasing? Why is that?
As you move down respiratory path, the radius does decrease significantly, however the Quantity of pathways increases as it branches so resistance is low compared to the many millions amount of branches in the respiratory system.
What are the factors that can affect AIRWAY RESISTANCE?
- Lung volume (bronchi dilate as lungs expand)
- bronchial smooth muscles, innervated by 2 nerves :
PNS nerves = bronchoconstriction
SNS nerves = brnchodilation - Stimuli causing brochoconstriction ( smoking,dust,irritants,histamine)
What is FVC?
amount of air you can breath out after a max inhalation
What is FEV1?
- the amount of air expired in 1s
What is FEV1 as percentage in relation to FVC?
70-80%
What does the PEAK FLOW METER measure?
it measures the SPEED at which you are able to breathe out
What can be used to measure lungs and volume capacities?
spirometer
What is tidal volume?
volume of air inhaled/exhaled in one quiet breath
What is ERV?
- it is the max amount of volume one can expire after a normal tidal vol exhalation
What is IRV?
In the max amount of air one can inspire after a normal tidal after a normal tidal inhalation
What is residual volume?
Air remaining in lungs after MAXIMUM expiration
What is TV in males and females?
500 ml in both
What is ERV in males and females?
M = 1000 ml
F = 700 mL
What is IRV in males and female in mL?
M = 3300 mL
F = 1.9 mL
What is residual vol in male and female in L?
M = 1.2 L
F = 1.1 L
What is vital capacity in average MALE?
4800 ml
What is vital capacity in average female?
4200 mL
How can vital capacity be calculate?
VC= TV + IRV + ERV
How can inspiratory capacity be calculated?
TV +IRV
What is FRC and how can it be calculated?
- FRC = RV + ERV
it is the volume of air remaining after a normal tidal exhalation
How can TOTAL lung capacity be calculated?
TV + IRV + ERV + RV
What is tot lung capacity in MALES?
6 L
What is tot lung capacity in FEMALES?
4.2 L
How can PULMUNARY VENTILATION RATE/RESPIRATORY MINUTE VOLUME be calculated ?
TV x Breathing frequency
What is anatomical dead space?
it is the volume of air that does NOT participate in gas exchange in the conducting passages
How does Pulmonary ventilation rate and alveolar respiration rate differ?
alveolar respiration rate excludes the ANATOMICAL DEAD volume of air, so it actually accounts for air that only reaches lungs for gas exchange whereas pulmonary ventilation rate does include anatomical dead volume
What is the formula to calculate alveolar ventilation rate?
BF x (TV - anatomical dead volume)
Who have larger lung volumes?
- Males
- Taller
- Athletes
- High altitude’
- Non- smokers
