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Questions and Answers
What happens to the absolute pressure as you travel vertically up the lung?
What happens to the absolute pressure as you travel vertically up the lung?
Which zone of the lung has no blood flow?
Which zone of the lung has no blood flow?
What is the primary determinant of blood flow in Zone II?
What is the primary determinant of blood flow in Zone II?
Which zone is characterized by continuous blood flow?
Which zone is characterized by continuous blood flow?
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Which condition is NOT associated with an increase in Zone IV?
Which condition is NOT associated with an increase in Zone IV?
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What is the primary factor that affects the ventilation distribution in the lungs?
What is the primary factor that affects the ventilation distribution in the lungs?
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The ventilation/perfusion (V/Q) mismatch is greatest in which part of the lung?
The ventilation/perfusion (V/Q) mismatch is greatest in which part of the lung?
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What is the effect of gravity on the distribution of perfusion?
What is the effect of gravity on the distribution of perfusion?
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What is the primary difference between the alveolar gas composition at the apex and the base of the lung?
What is the primary difference between the alveolar gas composition at the apex and the base of the lung?
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Which zone of the lung occupies the major portion of the lung?
Which zone of the lung occupies the major portion of the lung?
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Which of the following accurately describes the role of the apneustic center?
Which of the following accurately describes the role of the apneustic center?
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Which sensory receptors are primarily responsible for detecting changes in arterial PO2?
Which sensory receptors are primarily responsible for detecting changes in arterial PO2?
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What is the main function of the pneumotaxic center?
What is the main function of the pneumotaxic center?
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Which of the following accurately describes the function of pulmonary stretch receptors?
Which of the following accurately describes the function of pulmonary stretch receptors?
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Which of the following is NOT a known function of J receptors?
Which of the following is NOT a known function of J receptors?
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Which of the following is a common response triggered by the activation of irritant receptors?
Which of the following is a common response triggered by the activation of irritant receptors?
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Which of the following muscles is primarily responsible for expiration during quiet breathing?
Which of the following muscles is primarily responsible for expiration during quiet breathing?
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Which of the following accurately describes the location of central chemoreceptors?
Which of the following accurately describes the location of central chemoreceptors?
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Which nerve carries sensory information from the carotid body to the respiratory center?
Which nerve carries sensory information from the carotid body to the respiratory center?
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Which of the following accurately describes the function of bronchial C fibers?
Which of the following accurately describes the function of bronchial C fibers?
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What is the primary role of pulmonary surfactant?
What is the primary role of pulmonary surfactant?
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Which of the following can decrease surfactant production?
Which of the following can decrease surfactant production?
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What is the normal humidity of air entering the trachea?
What is the normal humidity of air entering the trachea?
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What is a consequence of dry air entering the trachea?
What is a consequence of dry air entering the trachea?
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Which substance is primarily found in pulmonary surfactant?
Which substance is primarily found in pulmonary surfactant?
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What percentage of cardiac output is associated with anatomic shunt?
What percentage of cardiac output is associated with anatomic shunt?
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Which of the following volumes represents the air left in the lungs after maximum exhalation?
Which of the following volumes represents the air left in the lungs after maximum exhalation?
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What causes hypoxemia that is not responsive to increased FiO2?
What causes hypoxemia that is not responsive to increased FiO2?
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Which lung capacity consists of two or more lung volumes?
Which lung capacity consists of two or more lung volumes?
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What is the normal value of Inspiratory Reserve Volume (IRV)?
What is the normal value of Inspiratory Reserve Volume (IRV)?
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What is the primary effect of the Hering & Breuer inflation reflex?
What is the primary effect of the Hering & Breuer inflation reflex?
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Which receptors are primarily responsible for the detection of high CO2 levels?
Which receptors are primarily responsible for the detection of high CO2 levels?
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Which factor is known to significantly increase ventilation during exercise?
Which factor is known to significantly increase ventilation during exercise?
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What role do peripheral chemoreceptors play in respiratory control?
What role do peripheral chemoreceptors play in respiratory control?
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What is the main trigger for the deflation reflex?
What is the main trigger for the deflation reflex?
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Which reflex is paradoxically associated with encouraging deeper breaths?
Which reflex is paradoxically associated with encouraging deeper breaths?
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How does a reduction in pH affect ventilation?
How does a reduction in pH affect ventilation?
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What is normal lung compliance as measured in L/cm H2O?
What is normal lung compliance as measured in L/cm H2O?
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What is one of the primary functions of the lungs?
What is one of the primary functions of the lungs?
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Which of the following is a role of the lung's metabolic and endocrine functions?
Which of the following is a role of the lung's metabolic and endocrine functions?
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Which part of the brain mainly controls respiration?
Which part of the brain mainly controls respiration?
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Which type of medullary neurons are associated with inspiration?
Which type of medullary neurons are associated with inspiration?
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Which of the following statements is NOT a function of the respiratory tract?
Which of the following statements is NOT a function of the respiratory tract?
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What is a major role of alveolar macrophages?
What is a major role of alveolar macrophages?
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Which receptors are critical in the respiratory control system?
Which receptors are critical in the respiratory control system?
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What is one of the functions of secretory immunoglobulins (IgA) in the respiratory tract?
What is one of the functions of secretory immunoglobulins (IgA) in the respiratory tract?
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Flashcards
Lung functions
Lung functions
Includes gas exchange, sound production, and olfactory sensations.
Gas exchange
Gas exchange
Process of oxygen and carbon dioxide exchange in lungs.
Respiratory control system
Respiratory control system
Regulates breathing with a central controller, sensors, and muscles.
Medullary respiratory center
Medullary respiratory center
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Alveolar Macrophages
Alveolar Macrophages
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Olfactory sensations
Olfactory sensations
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Lung protection mechanisms
Lung protection mechanisms
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Surfactant synthesis
Surfactant synthesis
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Venous admixture
Venous admixture
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Anatomic Shunt
Anatomic Shunt
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Capillary Shunt
Capillary Shunt
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Residual Volume (RV)
Residual Volume (RV)
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Lung Capacities
Lung Capacities
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Lung Stretch Receptors
Lung Stretch Receptors
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Hering-Breuer Inflation Reflex
Hering-Breuer Inflation Reflex
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Deflation Reflex
Deflation Reflex
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Head's Paradoxical Reflex
Head's Paradoxical Reflex
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CO2's Role
CO2's Role
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Oxygen and Hypoxia
Oxygen and Hypoxia
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pH Impact on Ventilation
pH Impact on Ventilation
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Lung Compliance
Lung Compliance
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Pulmonary Surfactant
Pulmonary Surfactant
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Surfactant Composition
Surfactant Composition
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Effects of Surfactant Absence
Effects of Surfactant Absence
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Factors Decreasing Surfactant
Factors Decreasing Surfactant
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Humidity Levels in Airway
Humidity Levels in Airway
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Apneustic Centre
Apneustic Centre
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Pneumotaxic Centre
Pneumotaxic Centre
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Central Chemoreceptors
Central Chemoreceptors
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Peripheral Chemoreceptors
Peripheral Chemoreceptors
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Pulmonary Stretch Receptors
Pulmonary Stretch Receptors
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Irritant Receptors
Irritant Receptors
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Juxtacapillary Receptors
Juxtacapillary Receptors
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Bronchial C Fibers
Bronchial C Fibers
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Respiratory Muscles
Respiratory Muscles
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Role of CO2 and H+
Role of CO2 and H+
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Particle size: 5µm
Particle size: 5µm
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Particle size: 1µm
Particle size: 1µm
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Ideal particle size
Ideal particle size
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Upright posture and ventilation
Upright posture and ventilation
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Supine posture ventilation
Supine posture ventilation
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Zone I of pulmonary perfusion
Zone I of pulmonary perfusion
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Zone II of pulmonary perfusion
Zone II of pulmonary perfusion
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Zone III of pulmonary perfusion
Zone III of pulmonary perfusion
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Zone IV characteristics
Zone IV characteristics
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V/Q mismatch
V/Q mismatch
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Study Notes
Structure and Function of Respiratory Tract in Relation to Anaesthesia
- The respiratory tract plays a vital role in anaesthesia.
- Understanding its functions and structure is crucial for effective anaesthesia management.
Lung Functions
- Provides a large surface area for gas exchange.
- Moves air to and from the gas-exchange surfaces of the lungs.
- Produces sounds for speech.
- Provides olfactory sensations to the central nervous system (CNS).
- Acts as a reservoir for blood, available for circulatory compensation.
- Filters the circulation (e.g., removing thrombi and microaggregates).
- Regulates blood pH.
- Protects respiratory surfaces from dehydration and temperature changes.
- Provides nonspecific defenses against pathogens (e.g., secretory immunoglobulins, collectins).
- Involves peptide and protease activity, reactive oxygen species, and alveolar macrophage function.
- Involves the production and regulation of phospholipids (surfactant), proteins, and mucopolysaccharides in bronchial mucus.
- Lung functions involve metabolic and endocrine functions, such as handling biologically active substances in the pulmonary vascular bed.
- Certain substances aren't affected by lungs, while others are cleared or activated by them.
- Lungs handle various biologically active substances.
- Presents a diagram of two protease pathways sharing angiotensin converting enzyme.
Control of Respiration
-
Basic elements of the respiratory control system are:
- Central controller
- Strategically placed sensors
- Respiratory muscles
-
Central controller:
- Medullary respiratory centre
- Dorsal medullary respiratory neurons - associated with inspiration.
- Neuron group responsible for the basic rhythm of breathing, activating reticulospinal tract in the spinal cord, and stimulating respiratory muscles.
- Ventral medullary respiratory neurons - associated with expiration.
- Silent during quiet breathing; activated during forced expiration.
- Dorsal medullary respiratory neurons - associated with inspiration.
- Medullary respiratory centre
-
Apneustic centre: located in the lower pons
- Exact role in normal breathing is unknown.
- Respiration becomes shallow and irregular without constant influence from this centre.
-
Pneumotaxic centre:
- Located in the upper pons.
- Has an inhibitory effect on inspiratory and apneustic centres.
- Responsible for terminating inspiration by inhibiting activity of dorsal medullary neurons.
- Regulates respiration volume and rate.
-
Sensors
- Central chemoreceptors
- Located near ventral surface of medulla.
- Affected by changes in H+ concentration in brain extracellular fluid (ECF).
- Increase in H+ stimulates chemoreceptors leading to hyperventilation.
- Peripheral chemoreceptors
- Located in carotid artery bifurcation and aortic arch.
- Connected to respiratory centre in medulla.
- Respond to decreased arterial PO2, increased PCO2, and increased H+.
- Rapidly respond.
- Central chemoreceptors
Pulmonary Stretch Receptors
- Lie in airway smooth muscles.
- Sensitive to lung distension.
- Reflex action inhibits inspiratory activity, causing bronchodilation, and regulates breathing rate/depth.
- Insensitive to pathological changes like microembolism.
- Weakly sensitized by pulmonary congestion.
Irritant Receptors
- Rapidly adapting.
- Lie in airway epithelial cells.
- Activated by noxious gases, cigarette smoke, dust, and cold air.
- Cause bronchoconstriction, hyperpnea, and hyperventilation.
J (Juxtacilliary) Receptors
- Ending of nonmyelinated C fibers in alveolar wall close to capillaries.
- Activated by hyperinflation and inhaled strong irritants (e.g., halothane).
- Trigger tachypnea, rapid shallow breathing, bronchoconstriction, and apnea.
- Play a role in rapid shallow breathing and dyspnea associated with left heart failure (LHF) and interstitial lung disease (ILD).
Bronchial C Fibers
- Supplied by bronchial circulation.
- Activated by hyperinflation and injected chemicals.
- Trigger rapid shallow breathing, bronchoconstriction, and mucus secretion.
Other Lung Receptors
- Cough receptors in the trachea's epithelium.
- Pulmonary arterial baroreceptors.
Lung Receptors Summary Table
- Presents a summary table showing the response of different types of lung receptors to various stimuli.
Respiratory Tract Reflexes
- Hering-Breuer Inflation Reflex—inflation inhibits further inspiratory activity; mediated by pulmonary stretch receptors; uncommon during quiet breathing; barbituates suppress this reflex.
- Deflation Reflex—deflation initiates inspiratory activity.
- Head's Paradoxical Reflex—stimulates deeper breaths rather than inhibiting further inspiration; responsible for sighs and initial breaths of infants.
Factors Affecting Respiration
- CO2: Most important stimulus acting on central chemoreceptors, but peripheral chemoreceptors also contribute. Magnified when O2 is low. Response is reduced in sleep, older age, trained athletes, and drug users.
- O2 (Hypoxia): Only peripheral chemoreceptors are involved, and a negligible role during normoxia. Crucial in high altitudes with chronic hypoxia.
- pH: Reduced pH stimulates ventilation, with peripheral chemoreceptors as the site of action.
- Exercise: Leads to increased ventilation, with several theorized mechanisms, including changes in body temperature, and stimuli from the motor cortex affecting arterial Po2 and Pco2.
Factors Affecting Breathing
- Presents a table summarizing factors influencing breathing, including stimulated receptors, responses, and effects.
Static Characteristics of the Lungs
-
Compliance - Effort needed to stretch lungs.
- Formula: CT (L/cm H₂O) = ΔV(L)/ΔP(cmH₂O).
- Normal value: 0.2-0.3 L/cm H₂O.
- Reduced compliance, e.g., pulmonary fibrosis, alveolar edema, and atelectasis.
- Increased compliance, e.g., emphysema
-
Resistance - Relationship between pressure gradient and rate of air flow. '- Formula: R(cmH₂O/L/sec)= ΔP(cmH₂O)/ ΔV(L/sec)
- Depends on airway diameter, airflow rate, and airflow pattern.
- Airflow types include laminar flow (bronchi) and turbulent flow (trachea)
- Normal value: 1cmH2O/L/sec.
- Conditions that increase resistance include low lung volumes, increased gas density, decreased arterial PCO2, and cholinergic drugs.
- Depends on airway diameter, airflow rate, and airflow pattern.
Surface Tension
- Molecular force on a liquid's surface, drawing the surface area to a minimum size.
- Laplace law states that the pressure across a curved surface is twice the surface tension at the liquid interface, divided by the radius (P = 2T/R).
- Alveolar surfactant reduces surface tension in alveoli, preventing alveolar collapse at low lung volumes.
Pulmonary Surfactant
- Reduces surface tension of alveolar lining.
- Produced by type II alveolar epithelial cells.
- Contains dipalmitoyl phosphatidylcholine.
- Absence leads to reduced lung compliance, alveolar atelectasis, and pulmonary edema.
Factors Decreasing Surfactant
- Oxygen therapy
- IPPV with high pressure
- Pulmonary collapse
- Reduced pulmonary circulation (e.g., embolism)
- Anaesthetic agents
- Patients undergoing valve replacement procedures
Humidification
- Normal humidification mechanism occurs through the nose and mouth.
- Bypassed in endotracheal intubation (ETT) or tracheostomy.
- Humidification benefits include protecting mucosal drying, reducing heat loss, and reducing coughing and breath holding during inhalational introduction.
Dry Air Entering the Trachea
- Dry air triggers an inflammatory response.
- Leads to dried, tenacious secretions making removal difficult.
- Also damages/inhibits cilia.
- Leads to cilia loss & keratinization of tracheal epithelium.
Humidity
- Normally, trachea air is saturated with water vapor (~34 g/m³ at 34°C).
- Methods for artificially increasing humidity include humidifying the environment (e.g., incubators) and humidifying inspired gases (e.g., humidifiers).
Size of Droplets
- Varying sizes of water droplets have different effects on the respiratory system.
- Large droplets form pools in the upper respiratory tract,
- 5 µm droplets fall in the trachea.
- 1 µm droplets go to the alveoli and are generally ideal for deposition.
- Extremely stable droplets can be inspired and exhaled again.
Ventilation and Perfusion
- Upright posture: Ventilation is higher at the base of the lung than at the apex.
- Supine posture: Posterior areas are better ventilated than anterior ones.
- Lateral position: Dependent lung is best ventilated.
- Describes normal lung zones.
Distribution of Pulmonary Perfusion
- Presents several details regarding pulmonary zones (zones I-IV).
- Discusses how blood flow changes throughout zones.
Distribution of Ventilation
- Describes how pleural pressure increases and alveolar volume decreases down the lung.
- Dependent alveoli are more flexible (steep slope) compared to non-dependent alveoli (flat slope).
Ventilation/Perfusion Mismatch
- Presents a graph illustrating ventilation/perfusion mismatches, showing how ventilation and blood flow are related along the length of the lung.
V/Q Ratio and Regional Gas Composition in Alveoli
- Describes how alveoli (bottom and top) differ in their oxygen and CO2 retaining capacities.
- Explains that the V/Q ratio is lower at the base and higher at the top of the lung, which affects regional gas composition.
Shunt – Venous Admixture
- Occurs when blood flows through the lung without proper oxygenation.
- Anatomic shunt: portion bypasses pulmonary capillaries (2% of blood volume).
- Capillary shunt: perfuses non-ventilated alveoli (e.g., atelectasis, edema, pneumonia).
- Hypoxemia—not responsive to FiO2 increase.
Lung Volumes and Capacities
- Defines and describes the four lung volumes (tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and residual volume (RV)).
- Defines the following lung capacities (vital capacity (VC), inspiratory capacity (IC), functional residual capacity (FRC), and total lung capacity (TLC).
- Explains that these four measures are used during lung testing such as spirometry.
- Illustrates lung volumes and capacities graphically.
Lung Volumes
- Definitions of tidal volume (TV), inspiratory reserve volume (IRV), and expiratory reserve volume (ERV).
- Values for these pulmonary measures under normal conditions (N).
Lung Volumes and Capacities
- Defines residual volume (RV), functional residual capacity (FRC), and total lung capacity (TLC), along with measurement methods (e.g., helium dilution, body plethysmography).
Respiratory Function During Anaesthesia
- Anaesthesia impairs pulmonary function, whether the patient is breathing spontaneously or mechanically ventilated.
- Impaired oxygenation of blood occurs during anaesthesia; therefore, FiO2 is maintained at 0.3-0.4.
- Clinically significant pulmonary complications after surgery (1-2% after minor surgeries and up to 20% after major)
Lung Volume & Respiratory Mechanics During Anaesthesia
- FRC is decreased by about 20% during anaesthesia.
- Respiratory muscle tone decreases, and the diaphragm shifts cranially.
- Lung compliance is reduced, leading to decreased ventilation volume.
- Airway resistance increases due to decreased airway dimensions.
Atelectasis During Anaesthesia
- Atelectasis occurs in 90% of anaesthetized patients, both with spontaneous breathing and after muscle paralysis.
- Development is affected by pre-oxygenation and surgery-related factors (e.g. FiO2, PEEP, postoperative O2, body mass index).
- Obese/high body mass index patients experience more extensive atelectasis.
- No correlation found between age and atelectasis incidence.
Prevention of Atelectasis
- Discusses application of PEEP, recruitment maneuvers, minimizing gas resorption by using low FiO2 during and post anaesthesia.
Hypoxic Pulmonary Vasoconstriction (HPV)
- Physiological mechanism that optimizes ventilation-perfusion matching. Blood flow diverted from poorly ventilated areas to well-ventilated ones
- Inhaled anaesthetics inhibit HPV.
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Description
Test your knowledge on lung physiology and blood flow dynamics with this quiz. Delve into various lung zones, their characteristics, and the factors affecting ventilation and perfusion. Perfect for students studying respiratory physiology or related health sciences.
