Pulmonary Physiology Flashcards
What is the equation to calculate the pressure/volume relationship in the lungs?
P1V1 = P2V2
As the lung volume increases, what happens to the pressure?
Decreases
As the lung volume decreases, what happens to the pressure?
Increases
What is the Barometric pressure (Pb) value?
760 mmHg = 0 cm H2O
What is the pressure of Oxygen value?
150 mmHg
The pressure in the lungs has to be ____ than the barometric pressure in order for air to enter the lungs
LESS
Which direction does the chest wall want to go?
Expand
Which direction do the lungs want to go?
Collapse
From the lungs to superficial, what is the order of the anatomy?
Lungs Visceral Pleura Intrapleural space (parietal fluid) Parietal Pleura Muscles/ribs
Intrapleural pressure (Ppl) is a _____ number
NEGATIVE
What is the value of the intrapleural pressure at rest?
-5 cm H2O
With inspiration, what happens to the value of the intrapleural pressure?
Volume increases = pressure will decrease
** Intrapleural pressure goes from -5 –> -8 cm H2O
== -8 cm H2O
What is the value of the alveolar pressure at rest?
Alveolar pressure = Barometric pressure
== 0 cm H2O
With inspiration, what happens to the value of the alveolar pressure?
Volume increases = pressure will decrease
** Alveolar pressure goes from 0 –> -1 cm H2O
== -1 cm H2O
Why does air enter the lungs when the alveolar pressure is -1 cm H2O?
It is now LESS than the barometric pressure (0), so air will enter!!
What is the equation for the Transpulmonary pressure?
Alveolar pressure - Intrapleural pressure
What is the value of the Transpulmonary pressure at rest?
0 - (-5) == 5 cm H2O
At REST, Describe the volume, alveolar and intrapleural pressures
Volume = 0
Alveolar pressure = 0
Intrapleural pressure = -5
At MID-INSPIRATION, Describe the volume, alveolar and intrapleural pressures
Volume is INCREASING
Alveolar pressure = -1
Intrapleural pressure is decreasing
At END of INSPIRATION, Describe the volume, alveolar and intrapleural pressures
Volume has peaked = 500 mL
Alveolar pressure has returned to 0
Intrapleural pressure = -8
At MID-EXPIRATION, Describe the volume, alveolar and intrapleural pressures
Volume is DECREASING
Alveolar pressure = +1
Intrapleural pressure is increasing
At END of EXPIRATION, Describe the volume, alveolar and intrapleural pressures
Volume = 0
Alveolar pressure = 0
Intrapleural pressure = -5
– back to resting state
Minute Ventilation (VE)
Volume of air inspired every minute
= RR X Tidal volume
What is a normal minute ventilation?
14 X 500 mL = 7 L/min
Area of lungs and airways where gas exchange does NOT occur
Dead space
What are the 3 types of dead space?
- Anatomic
- Alveolar
- Physiological
Anatomic dead space (mL) is equal to?
A person’s weight
Alveolar dead space is usually?
0
In a healthy person, physiological dead space is equal to?
Anatomic dead space
Equation for physiological dead space
Physiological dead space = anatomical dead space + alveolar dead space
How do you calculate minute alveolar ventilation?
Subtract dead space from the tidal volume and then multiply by the RR
Low compliance means?
Low stretch ability = harder to inflate the lungs
High compliance means?
Very stretchable = easy to inflate the lungs
At low lung volumes, what is the compliance?
LOW - harder to inflate
At normal lung volumes, what is the compliance?
HIGH - easier to inflate
At high lung volumes, what is the compliance?
LOW - harder to inflate
Difference between inspiration and expiration due to surfactant
Hysteresis
With emphysema, compliance is ____
INCREASED - harder to expel air
With fibrosis, compliance is ____
DECREASED - harder to inspire air
As age increases, compliance
INCREASES
Compliance is the opposite of?
Elasticity
People with emphysema breathe at ____ volumes
HIGHER
People with fibrosis breathe at _____ volumes
LOWER
Alveoli hold each other open; thus loss of them will lose forces that normally counter collapse
Interdependence
What 2 forces must the work of breathing overcome?
Elastic
Resistant
With restrictive lung disease, what work changes?
Elastic
With obstructive lung disease, what work changes?
Resistive
