Questions and Answers
What is the primary determinant of airway resistance?
Which of the following would increase lung compliance?
A patient with airflow obstruction would likely have a decreased:
Dynamic compression of airways occurs during:
Signup and view all the answers
Which of the following is NOT a symptom of increased work of breathing?
Signup and view all the answers
Spirometry is a test of lung function that measures:
Signup and view all the answers
What is the relationship between flow and pressure difference according to Darcy's Law?
Signup and view all the answers
Which of the following is NOT a factor that determines resistance to flow?
Signup and view all the answers
What happens to flow rate if the radius of a tube is halved, assuming the same pressure gradient?
Signup and view all the answers
What is the main site of airway resistance in the respiratory system?
Signup and view all the answers
What is the equivalent of voltage in the context of flow through tubes?
Signup and view all the answers
What is the relationship between resistance to flow and the length of a tube?
Signup and view all the answers
What is the site of highest individual airway resistance?
Signup and view all the answers
According to Darcy's Law, what is the relationship between flow and resistance to flow?
Signup and view all the answers
What is the primary mechanism by which high intrapleural pressures cause dynamic compression of airways during forced expiration?
Signup and view all the answers
What is the main site of maximum airway resistance in the lungs?
Signup and view all the answers
What is the effect of dynamic compression of airways on expiratory airflow in normal people?
Signup and view all the answers
What is the unit of measurement for lung compliance?
Signup and view all the answers
What is the primary determinant of elastic resistance in the lungs?
Signup and view all the answers
What is the role of neural inspiratory activity in regulating airway diameter?
Signup and view all the answers
What is the primary mechanism by which adrenaline (in blood) affects airway diameter?
Signup and view all the answers
What is the effect of high RAW on expiratory airflow in people with lung disease?
Signup and view all the answers
What is the primary factor affecting airway diameter during forced expiration?
Signup and view all the answers
What is the term used to describe the effort-independent nature of expiratory airflow at low lung volumes?
Signup and view all the answers
In a patient with lung fibrosis, which of the following is true?
Signup and view all the answers
What is the characteristic feature of the flow-volume loop in obstructive airway disease of smaller airways?
Signup and view all the answers
During respiratory muscle weakness, which of the following is true regarding FRC?
Signup and view all the answers
What is the effect of emphysema on lung compliance?
Signup and view all the answers
Which of the following would lead to an increased FEV1/FVC ratio?
Signup and view all the answers
What is the relationship between FEV1 and FVC in restrictive disease?
Signup and view all the answers
Surfactant plays a crucial role in reducing which of the following at the alveolar air-fluid interface?
Signup and view all the answers
What is the effect of lung stiffness on FRC?
Signup and view all the answers
A patient with emphysema would likely have which of the following?
Signup and view all the answers
What is the feature of the flow-volume loop in normal individuals?
Signup and view all the answers
Which of the following would be affected by changes in stiffness of the lungs?
Signup and view all the answers
What is the effect of lung fibrosis on lung compliance?
Signup and view all the answers
What is the characteristic feature of the flow-volume loop in restrictive lung disease?
Signup and view all the answers
What is the effect of asthma on lung compliance?
Signup and view all the answers
Study Notes
Lung Mechanics 2
Factors Affecting Airway Resistance
- Two main sources of resistance to breathing: elastic resistance of the lung and airway resistance
- Airway resistance is affected by two main factors:
- Factors within the airways (bronchial smooth muscle tone, inflammation of epithelium with hypertrophy of glands and secretions)
- Pressure across the airway wall (negative intrapleural pressure in normal breathing, positive intrapleural pressure in forced expiration)
- Medium-sized bronchi (around generation 3-5) contribute most to airway resistance
Dynamic Compression of Airways
- Occurs when airway pressure falls below pleural pressure during a forced expiration
- Airways most likely to collapse are bronchi around generation 3 or 4
- Causes limitation of expiratory airflow at low lung volumes (effort-independent airflow)
- In lungs with high airway resistance, it causes marked limitation of airflow, leading to slow expiration, low peak expiratory flow rate, air trapping, and expiratory wheezes
Lung Compliance
- Elastic resistance of the lung, usually measured as compliance (stretchiness)
- Compliance = change in lung volume / change in transpulmonary pressure
- Healthy lungs have high compliance (easy to expand), while stiff lungs have low compliance (hard to expand)
- Lung fibrosis (scarred/stiff) has low compliance, while emphysema (tissue destruction/floppy) has high compliance
- Asthma does not usually affect compliance
Measuring Lung Compliance
- Transmural pressure gradient = alveolar pressure - intrapleural pressure
- Intrapleural pressure measured with an oesophageal balloon, volume measured with a spirometer
- Subject breathes in from RV to TLC in steps to measure compliance
Simple Tests of Lung Function
- Spirometry: measures lung function and detects airflow obstruction
- FEV1 (forced expiratory volume in 1 second): measures airflow obstruction
- FVC (forced vital capacity): measures lung size and detects restrictive lung disease
- FEV1/FVC ratio: detects airflow obstruction (normal > 0.7)
- Peak expiratory flow rate: measures airflow obstruction and detects small airway disease
Effects of Chest Wall & Pulmonary Restriction and Airflow Obstruction
- Chest wall and pulmonary restriction: decrease FEV1, FVC, and peak expiratory flow rate
- Airflow obstruction: decrease FEV1, FEV1/FVC ratio, and peak expiratory flow rate, while FVC may be normal or decreased
Surface Tension Forces and Surfactant
- Surface tension forces at the alveolar air-fluid interface important for lung expansion and stability
- Surfactant: a complex mixture of lipids and proteins produced by type II alveolar cells, reduces surface tension and facilitates lung expansion
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the main sources of resistance to breathing, including elastic resistance and airway resistance, and the factors that affect airway resistance, such as bronchial smooth muscle tone and intrapleural pressure. Learn about the mechanisms that influence airway resistance in normal breathing and forced expiration.