Lecture 5 (Test 2) Flashcards
What does spirometry measure?
Spirometry measures how lung volume changes as someone breathes, including normal breathing and deep breathing.
Spirometry tracks the air coming into and leaving the patient.
What are the three main lung volumes measured by spirometry?
- Tidal Volume (TV)
- Inspiratory Reserve Volume (IRV)
- Expiratory Reserve Volume (ERV)
What is vital capacity?
Vital capacity is the total volume of air that can be inhaled and exhaled in a single maximal effort breath, calculated as TV + IRV + ERV.
It represents the working volume of the lungs.
What is a limitation of basic spirometry?
Basic spirometry cannot measure any lung capacities that include residual volume (RV) and functional residual capacity (FRC).
Residual volume cannot be expelled from the lungs for measurement.
What is the purpose of using an indicator gas in advanced spirometry?
An indicator gas, like helium, is used to measure lung volumes that cannot be expelled, such as residual volume and functional residual capacity.
Helium is cheap and inert, making it suitable for these measurements.
How does the dilution of helium help in measuring lung volume?
The dilution of helium in the lungs indicates how much air is present; knowing the starting concentration and volume allows calculation of lung volumes.
The final concentration helps determine the volume of air in the lungs.
What is pulmonary compliance?
Pulmonary compliance refers to the ease with which the lungs expand under pressure.
It is represented by the slope of the pressure-volume curve.
How does emphysema affect lung compliance?
Emphysema increases lung compliance due to the loss of elastic tissue, making it easier to fill the lungs but harder to expel air.
What characterizes restrictive lung diseases?
Restrictive lung diseases are characterized by low compliance, making it harder to fill the lungs with air.
Examples include pulmonary fibrosis.
What is hysteresis in lung function?
Hysteresis refers to the difference in lung behavior during inspiration and expiration.
How does the lung behave differently during inspiration and expiration?
The lung is generally more compliant during expiration than during inspiration, leading to a delay in air intake at low lung volumes.
What happens when air in the lungs is replaced with saline?
Replacing air with saline reduces hysteresis and increases compliance, making the lung behavior similar during inspiration and expiration.
What causes the difference in compliance between air-filled and saline-filled lungs?
The difference is caused by surface tension in the alveoli, which is affected by the presence of air.
What is the primary indicator gas used in advanced spirometry?
Helium is the primary indicator gas used due to its cost-effectiveness and inert properties.
What is the formula to calculate vital capacity from total lung capacity and residual volume?
TLC - RV = VC
True or False: Obstructive lung diseases typically result in reduced lung volumes.
False.
Obstructive lung diseases often result in abnormally high lung volumes.
What is pulmonary compliance?
The ability of the lungs to expand and contract in response to pressure changes.
What contributes to the compliance of the pulmonary system?
Surface tension is a large contributor to the overall compliance of the system.
What is the air-water interface in the alveoli?
It is the area where water meets gas or air inside the alveoli.
What effect does high surface tension have on inhalation?
It makes it difficult to put air into the lungs.
What role does surfactant play in the lungs?
Surfactant reduces surface tension, making it easier to fill the lungs with air.
What are the two main components of surfactant?
- Lipids (90%)
- Proteins (10%)
What are the four surfactant proteins?
- SP-A
- SP-B
- SP-C
- SP-D
Which surfactant proteins are hydrophilic?
- SP-A
- SP-D
Which surfactant proteins are hydrophobic?
- SP-B
- SP-C
What are the two most important phosphatidyl compounds in surfactant?
- Dipalmitoylphosphatidylcholine (31%)
- Unsaturated Phosphatidylcholine (31%)
What type of cells produce surfactant in the lungs?
- Goblet cells (upper airway)
- Clara cells (lower airways)
- Type 2 alveolar cells (alveoli)
What is the primary function of type 1 cells in the alveoli?
Gas exchange.
What is the primary function of type 2 cells in the alveoli?
Production of surfactant.
What is the process by which surfactant is released?
Exocytosis.
What percentage of the gas exchange surface area is made up by type 1 cells?
90 to 95%
What percentage of the gas exchange surface area is made up by type 2 cells?
5 to 10%
What is tubular myelin?
A netting structure where surfactant proteins and lipids are stored.
How does surfactant function during normal breathing?
Surfactant molecules are knocked off the netting and reduce surface tension at the air-water interface.
What happens to surfactant over time?
It falls apart and needs to be recycled by alveolar macrophages.
What is the role of alveolar macrophages?
To digest and recycle surfactant and remove debris.
What happens if surfactant production is not balanced with its decay?
Increased surface tension and difficulty in lung inflation.
How does negative alveolar pressure affect surfactant?
It helps to pull surfactant off the netting during inspiration.
How does positive pressure ventilation differ in effect on surfactant compared to negative pressure?
It does not knock off surfactant in the same way as negative pressure does.
What effect does negative alveolar pressure have on surfactant?
Negative alveolar pressure likely pulls surfactant off the netting.
How does positive pressure ventilation affect surfactant compared to negative pressure?
Positive pressure ventilation does not have the same effect on surfactant as negative pressure inspiration.
What happens to surfactant in a collapsed section of the lung?
Surfactant in the collapsed area will run out due to lack of air filling and recoiling.
What is the challenge in recruiting a collapsed area of the lung?
The challenge is that surface tension is higher in the collapsed area compared to open areas.
What role do Goblet cells play in the lungs?
Goblet cells are primarily mucus-secreting cells.
What are Clara cells?
Clara cells are another type of cell found in the lungs.
What are the two types of alveolar cells?
Type one and type two alveolar cells.
What is the function of mast cells in the lungs?
Mast cells release inflammatory mediators, such as histamine.
How many alveoli are typically found in young adults?
Approximately 500 million alveoli.
What is alveologenesis?
The process of forming new alveoli in the lungs.
How many capillaries are estimated to be attached to each alveolus?
Up to 1,000 capillaries.
What is the average alveolar surface area in a healthy 20-year-old adult?
About 70 square meters.
What is surface tension in the context of the lungs?
Surface tension is the force that causes water molecules to aggregate and affects air entry into alveoli.
What percentage of elastic recoil pressure is due to surface tension?
About 2/3 of normal elastic recoil pressure.
How does restrictive lung disease affect lung volumes?
Restrictive lung disease results in lower lung volumes due to increased tissue recoil.
How does obstructive lung disease affect lung volumes?
Obstructive lung disease results in higher lung volumes due to decreased tissue recoil.
What happens to surface tension in lung diseases?
There is usually a surfactant deficiency associated with every lung disease.
Fill in the blank: The force that allows water molecules to aggregate is called _______.
surface tension
True or False: Surface tension is usually a significant factor in lung function.
False
What happens to water molecules in a container over time?
They aggregate to form droplets due to surface tension.
What is the relationship between elastic recoil and tissue factors?
Elastic recoil pressure is influenced by tissue elasticity and surface tension.
What do water molecules prefer to interact with?
Other water molecules
Water molecules do not prefer to interact with air and tend to aggregate with each other.
What happens when water droplets are placed on glass and moved?
They form and aggregate on the side of the glass
This aggregation occurs because water molecules prefer to be close to each other.
What is an amphipathic molecule?
A molecule that is partially water soluble and partially lipid soluble
These molecules tend to position themselves at the air-water interface.
Where does a phospholipid orient itself in a water solution?
At the air-water interface with the polar head in water and the lipid tail sticking out
This orientation minimizes the interaction of the lipid tail with water.
What role do surfactants play in water molecules?
They prevent water molecules from clumping together
Surfactants can insert themselves between water molecules, reducing surface tension.
What is surface tension?
The force generated by water molecules wanting to be around other water
Surface tension causes water molecules to be attracted to each other, which can lead to droplet formation.
How do surfactants affect the alveoli?
They reduce surface tension, making alveoli more compliant
This allows for easier filling of the lungs with air.
What is the source of surfactants in the alveolus?
Type II cells and their associated mesh
These cells help produce surfactants that are essential for lung function.
What happens to surfactants under negative alveolar pressure?
They get nudged off the mesh and swim to the air-water interface
This positioning is crucial for effective lung function.
What effect does surfactant have on lung hydration?
It helps keep the lungs dry
Surfactants create a thinner layer of water, facilitating gas exchange.
How does lung volume affect airway resistance?
Higher lung volumes lead to lower airway resistance
Conversely, lower lung volumes increase airway resistance.
What happens to airway diameter at lower lung volumes?
The airway diameter decreases
This increased resistance limits the speed of exhalation.
What is the relationship between lung volume and exhalation speed?
High lung volumes = low airway resistance = faster exhalation
Low lung volumes increase airway resistance, slowing exhalation.
What holds larger airways open during normal breathing?
Negative pleural pressure
This traction helps maintain airway patency.
What is the role of connective tissue in lung function?
It tethers lung components together, aiding in air intake
Without these connections, air intake can be compromised.
How does negative pleural pressure affect alveoli and airways?
It helps maintain airway patency and allows for high alveolar volume
This is essential for effective gas exchange in the lungs.
