Natalie - Pulmonary Pressures Flashcards
Define pulmonary ventilation
The physical movement of air into and out of the lungs
What two things does the movement of air depend on?
Boyle’s Law
Compliance
What is Boyle’s Law
The pressure and volume of a gas are inversely proportional at constant temperature and volume
Define lung compliance
(2)
A measure of the ease at which our lungs can stretch
An indication of the expandability of the lungs
Describe the movement of air in relation to pressure
Air moves from high to low pressure
What pressures determine the direction of air flow in the lungs?
The relationship between the intra-pulmonary pressure and the atmospheric pressure determines the direction of air flow
What pressures determine the direction of air flow in the lungs?
The relationship between the intra-pulmonary pressure and the atmospheric pressure determines the direction of air flow
What is the intra-pulmonary pressure
Pressure inside the alveoli
What is the intra-pulmonary pressure
Pressure inside the alveoli
What is intra pleural pressure?
Pressure in the pleural cavity
What does intra-pleural pressure control?
It maintains pull on the lungs
List the three different types of pressures
Intra-alveolar/pulmonary pressure (pressure in the alveoli)
Atmospheric pressure
Intra-pleural pressure
What happens to the volume of the thorax during inhalation?
The volume increases during inhalation
What happens to the pressure in the lungs during inhalation and why?
Pressure decreases because the volume of the thorax increases (lungs expand and fill with air but have more room therefore less pressure)
What happens to the pressure in the lungs during exhalation
Volume of thorax decreases - air forced out of lungs so pressure increases
What pressure is responsible for keeping the lungs open?
Intra-pleural pressure
List the three pulmonary pressures
Intra alveolar pressure
Intra pleural pressure
Trans pulmonary pressure
Define tidal volume
The volume of air taken into the lungs at rest
Approximately 500 mls
Write a note on intra pleural pressure
(4)
It is always negative, never positive
If it goes above zero the lung collapses
Pressure must be lower than atmospheric pressure
Lower than alveolar pressure - allows alveoli to stay open - keeps about 1L of air in the lungs which never leaves
What are the two phases to breathing
Inhalation
Exhalation
What is inhalation?
Air is pulled into the lungs
What is exhalation?
Air is pushed out of the lungs
What is the overall function of breathing?
To deliver oxygen to the alveoli
To remove carbon dioxide
Define breathing
The continuous cycle of inhalation and exhalation
What is respiratory rate?
Amount of breaths per minute
Average = 10 to 15
What happens when the diaphragm contracts?
The diaphragm moves down - pulls lungs down - pulls air into lungs - inhalation
What happens when the diaphragm relaxes?
The diaphragm moves up - pushes lungs up - pushes air out of lungs - exhalation
State Boyle’s Law
For a given quantity of any gas (such as air) in a container, the
pressure is inversely related to the volume of the container
What happens to intra-pleural pressure as we inhale?
It gets more negative as we inhale as pleural fluid doesn’t expand (so its pressure drops)
What are two other names for intra-alveolar pressure?
Intra pulmonary pressure
Intra thoracic pressure
What two factors determine intra alveolar pressure?
Amount of air in the alveoli
The volume of the alveoli themselves
What is the loss of alveoli called?
Atelectasis
Why is pressure exerted outwards in the lung?
Pressure in the alveoli is higher than the intra pleural pressure
What happens to intra alveolar pressure during inhalation?
It decreases slightly but does NOT go below intra pleural pressure
What is trans pulmonary pressure?
The difference between the intra alveolar and intra pleural pressure
What happens to the trans pulmonary pressure during inhalation?
It increases during inhalation
What is a pneumothorax
(3)
Pneumothorax occurs when air leaks from inside of the lung to
the space between the lung and the chest wall.
The lung then collapses
It is the presence of air within the pleural space
What happens to pulmonary pressures during a pneumothorax?
Pressure is exerted INWARDS
Alveolar pressure lowers below intra pleural pressure (which increases)
