Respiratory Flashcards
What is Atmospheric Pressure?
760mmHg
What is Intrapulmonary Pressure?
760mmHg
What is Intrapleural Pressure?
756mmHg
What is the Collapsing Force of The Lungs?
4mmHg
What happens in Inspiration? (7 Steps)
- Inspiratory Muscles contract
- Thoracic Cage Expands
- Intrapleural Pressure becomes more negative
- Transmural Pressure increases and causes Alveoli to swell and open
- Intra-alveolar pressure falls relative to atmospheric pressure
- Air flows down pressure gradient from atmosphere into alveoli
- At the end of Inspiration–> No airflow, Intra-alveolar Pressure = Atmospheric Pressure
What happens in Passive Expiration?
Relaxation of the Expiratory Muscles
What happens in Active Expiration?
- Contraction of abdominal muscles
2. Contraction of internal intercostals
What are the 3 types of Muscles of Respiration?
- Primary
- Accessory
- Airway
What are the Primary Muscles of Respiration?
- Diaphragm
2. External Intercostals
What is the function of the Diaphragm?
Responsible for 75% of breathing, flattens upon contraction
What is the function of the External Intercostals (in relation in breathing)?
They lift the ribs upwards and outwards
What are the Accessory Muscles of Respiration?
- Scalene
2. Sternomastoid
What is the function of the Scalene Muscles (in relation to breathing)?
Raise the first 2 ribs
What is the function of the Sternomastoid (in relation to breathing)?
Raise the Sternum
What are the Airway Muscles of Respiration?
- Laryngeal
- Pharyngeal
- Genioglossus
What is the function of the Airway Muscles of Respiration
Enlarge and Stabilise the airway
What is Tidal Volume (TV)?
Volume of air breathed in and out each breath
What is the Inspiratory Reserve Volume (IRV)?
Inspiratory Capacity minus Tidal Volume
What is the Inspiratory Capacity (IC)?
Volume of air breathed in during maximal inspiration
What is the Expiratory Reserve Volume (ERV)?
Vital Capacity minus Inspiratory Capacity
What is the Residual Volume (RV)?
Volume of air in the lungs after maximal exhalation
What is the Functional Residual Capacity (FRC)?
Expiratory Reserve Volume + Residual Volume
What is the Vital Capacity (VC)?
Maximum volume of air able to be exhaled after a maximal inspiration
What is the Total Lung Capacity (TLC)?
Vital Capacity + Residual Volume
What is the Forced Vital Capacity (FVC)?
Maximal Inhalation followed by fast exhalation
What is the Forced Expiratory Volume in 1 Second (FEV1)?
Determined in Pulmonary Function Test
How is the Total Lung Capacity affected in Obstructive Respiratory Disease?
Not affected
How is the Total Lung Capacity affected in Restrictive Respiratory Disease?
Decreased
How is the Residual Volume affected in Obstructive Respiratory Disease?
Increased
How is the Residual Volume affected in Restrictive Respiratory Disease?
Not affected
How is the Forced Vital Capacity (FVC) affected in Obstructive Respiratory Disease?
Not affected or slightly decreased
How is the Forced Vital Capacity (FVC) affected in Restrictive Respiratory Disease?
Decreased
How is the FEV1 affected in Obstructive Respiratory disease?
Decreased
How is the FEV1 affected in Restrictive Respiratory Disease?
Decreased
How is the FEV1/FVC affected in Obstructive Respiratory Disease?
Decreased
How is the FEV1/FVC affected in Restrictive Respiratory Disease?
Not affected
What are the methods for Lung Volume Measurement?
- Peak Expiratory Flow Meter
- Helium Dilution Technique
- Body Plethysmography
What does Peak Expiratory Flow Meter measure?
Maximum speed of expiration–> measure of airway resistance
What does the Helium Dilution Technique measure?
Functional Residual Capacity (FRC)
What is the equation for FRC in the Helium Dilution Technique?
FRC = (C1 x V1) / (C2 - V1)
What does Body Plethysmography measure?
Functional Residual Capacity (FRC)
How does Body Plethysmography measure a patient’s Functional Residual Capacity (FRC)?
The Patient sits in an airtight chamber and tries to breathe through a closed mouthpiece. The patient’s chest and lungs expand, and the pressure in the lungs decrease. Meanwhile, the air volume in the chamber decreases and the pressure in the air chamber increases.
What is the equation for FRC in Body Plethysmography?
Change in Volume (Initial Pressure minus Change in Pressure) ÷ Change in Pressure
What is Boyle’s Law?
P1V1 = P2V2
What is Dead Space?
Volume occupied in lung by gas not involved in gas exchage
What are the different types of Dead Space in the lung?
- Anatomical Dead Space
- Alveolar Dead Space
- Physiological Dead Space
What is Anatomical Dead Space?
Anatomical Dead Space Volume = Tidal Volume - Alveolar Volume
How is Anatomical Dead Space measured?
Measured by Fowler’s Method (Nitrogen Washout)
Describe Fowler’s Method (Nitrogen Washout)
- Pure oxygen is breathed in, causing Nitrogen Concentration = 0
- During expiration, the nitrogen concentration is measured. Vd is when the Nitrogen concentration starts increasing from 0
What is Alveolar Dead Space?
Air in the alveoli in areas without blood flow
What is Physiological Dead Space?
Total Dead Space–> Alveolar Dead Space + Anatomical Dead Space
How is Physiological Dead Space measured?
Bohr’s Method
Describe Bohr’s Method
Vd is calculated using partial pressures of Carbon Dioxide in alveoli and expired air–> VD = VT [(PaCO2 - PeCO2)] / PaCO2
What is the effect of Dead Space on Ventilation?
Alveolar Ventilation = (VT - VD) x Breaths/min
What are 2 types of work of breathing?
- Compliance (Elastic) Work
2. Frictional/ Resistive Work
What is Compliance (Elastic) Work of the Lungs?
Compliance = The Stretching of the Lungs and Chest Wall = Change in Volume of the Lungs ÷ Change in Transmural Pressure
What is Transmural Pressure?
The pressure difference between the intra-alveolar pressure and the intrapleural pressure
What are the 3 types of Compliance?
- Static Compliance
- Dynamic Compliance
- Specific Compliance
When is Static Compliance measured?
When there is no airflow
When is Dynamic Compliance measured?
During Airflow
How is Dynamic Compliance measured?
Using a Hysteresis Loop
What is a Hysteresis Loop?
Graphical Representation of relationship between volume change and pressure change during quiet breathing
What is the work of breathing in a Hysteresis loop?
The area in the loop
What does Specific Compliance measure?
Measures the elastic properties of the lungs
What are the 2 things that contribute to Specific Compliance?
- Tissue Elasticity
2. Surface Tension
Describe Tissue Elasticity (Lung Compliance)
During Inhalation, Energy is required to stretch the lungs open–> In exhalation, the lungs makes use of the elastic recoil (due to elastin fibres in the connective tissue)
Describe Surface Tension (Lung Compliance)
Surface Tension = Phenomenon where the surface of liquid acts like a thin elastic sheet–> Will cause lung or alveolar collapse. High Surface Tension = Low Compliance
What counteracts Surface Tension in the lungs?
Pulmonary Surfactant
What is the function of surfactant?
Reduce surface tension by interfering with water molecule interactions –> increase compliance of the lung and stabilises alveoli of different sizes
What is the composition of surfactant?
- 40% Dipalmitoyl-Phosphotidylcholine (DPCC)
- 40% Other phospholipds including phosphotidylglycerol (7%)
- 5% Surfactant-Associated Proteins
- Cholesterol
- Traces of other substances
How is surfactant synthesised?
- Formation of Phosphatidylcholine (Lechtin) from: CDP-diacylglycererol + Alcohol or diacylglycerol + CDP-Choline/Ethanolamine
- Phosphatidylcholine –> Dipalmitoyl-Phosphotidylcholine (DPCC)
- DPCC joins to Apolipoproteins to form unique lipoprotein–> surfactant
What are the Surfactant Apolipoproteins?
SP-A,B,C and D
Which surfactant apolipoproteins are hydrophillic?
A and D
Which surfactant apolipoproteins are hydrophobic?
B and C
What is the function of hydrophillic surfactant apolipoproteins?
Crucial role in pulmonary immunity
What is the function of hydrophobic surfactant apolipoproteins?
- Reduce Alveolar Surface Tension
- Phospholipid Packaging
- Organisation of Surfactant Structure
What are the different types of cells in the lung?
- Smooth muscle cells
- Lung macrophages
- Mast Cells
- Gobet Cells
- Endothelial Cells
- Type 1 Alveolar Cells
- Type 2 Alveolar Cells
Where are the smooth muscle cells of the lungs located?
Bronchi
Where are the Lung Macrophages located?
They are Interspersed, found along the length of the respiratory tract
Where are the mast cells of the lungs located?
They are found along the length of the respiratory tract
Where are the Goblet cells of the lungs located?
They are present from Bronchioles upwards–> in the epithelium
Where are the Pulmonary Endothelial cells located?
Alveolar Wall
Where are the Type 1 Alveolar Cells located?
Alveoli–> Makes up 95% of the respiratory zone–> fuses with the Pulmonary Endothelium
Where are the Type 2 Alveolar Cells located?
Alveoli
What is the function of Smooth Muscle Cells in the lungs?
- Control the diameter and tension of the bronchi
- Involved in Asthma
- Produces Cytokines IL-5, IL-13
What is the function of Lung Macrophages?
Important for immune defence–> Phagocytosis, produce antimicrobial (Proteases) and antiviral (interferons) agents
What is the function of the mast cells in the lungs?
- Speed Immune Response
2. Important in Asthma
What is the function of the Goblet Cells in the lungs?
Secrete Mucus
What is the function of the Endothelial Cells?
- Environment for alveolar capillaries
- Produces Vasoactive Peptides–> tPA and ACE
- Control blood flow, fluidity, pressure and viscosity
What is the function of Type 1 Alveolar Cells?
Gas exchange
What is the function of Type 2 Alveolar Cells
- Synthesis, Storage and Secretion of Surfactant
2. Can replace themselves or other pulmonary cell types after injury
What is Frictional/Resistive Work of the Lungs?
Airway Resistance
What affects Airway Resistance in the Lungs?
- Diameter of Airway
- Distance Air needs to travel
- Flow type/Pattern
What affects the Diameter of Airway and the Distance air needs to travel in the lungs?
- Cross-sectional area of the Bronchial tree
- Lung volume (increased lung volume = decreased resistance)
- Bronchial Smooth Muscle Tone
- Mucus/Secretions
What is Hagen-Poiseuille Law?
Resistance = (8 x viscosity x length) ÷ (π x radius^4)
Where is the greatest resistance in the airways?
In Large Airways
What are the types of air flow?
- Laminar–> streamline & well-ordered
2. Turbulent –> Chaotic, Increases resistance
When does Turbulent Flow of air occur?
Occurs if Reynold’s number is greater than 2000
What is the Partial Pressure of Oxygen in Inspired air?
150mmHg
What is the Partial Pressure of Oxygen in Expired Air?
120mmHg
What is the Partial Pressure of Oxygen in Alveolar Air?
100mmHg
What is the Partial Pressure of Carbon Dioxide in Inspired Air?
0mmHg