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Questions and Answers
What is the primary function of the lungs regarding gas exchange?
What is the primary function of the lungs regarding gas exchange?
Which of the following is NOT a primary function of the respiratory zone?
Which of the following is NOT a primary function of the respiratory zone?
Which of the following accurately describes the process of ventilation?
Which of the following accurately describes the process of ventilation?
What type of alveolar cell is primarily responsible for gas exchange?
What type of alveolar cell is primarily responsible for gas exchange?
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How does the conducting zone differ from the respiratory zone in the respiratory system?
How does the conducting zone differ from the respiratory zone in the respiratory system?
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Which of the following best describes the role of surfactant in the alveoli?
Which of the following best describes the role of surfactant in the alveoli?
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Which of these is a component of the respiratory zone?
Which of these is a component of the respiratory zone?
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According to Boyle's Law, if the volume of the lungs increases during inspiration, what happens to the intrapulmonary pressure?
According to Boyle's Law, if the volume of the lungs increases during inspiration, what happens to the intrapulmonary pressure?
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What is the primary function of the mucociliary clearance mechanism in the conducting zone?
What is the primary function of the mucociliary clearance mechanism in the conducting zone?
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What is the primary role of the pleural fluid within the pleural cavity?
What is the primary role of the pleural fluid within the pleural cavity?
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Which cells are primarily responsible for secreting mucus in the airways?
Which cells are primarily responsible for secreting mucus in the airways?
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If the atmospheric pressure is 760 mm Hg, what would a negative respiratory pressure be, in mm Hg?
If the atmospheric pressure is 760 mm Hg, what would a negative respiratory pressure be, in mm Hg?
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How do the cilia on the ciliated epithelial cells move?
How do the cilia on the ciliated epithelial cells move?
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What is secreted by serous and club cells in the airways?
What is secreted by serous and club cells in the airways?
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Which of the following statements accurately describes the relationship between intrapulmonary pressure and atmospheric pressure during normal breathing?
Which of the following statements accurately describes the relationship between intrapulmonary pressure and atmospheric pressure during normal breathing?
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Which of the following is true about intrapleural pressure?
Which of the following is true about intrapleural pressure?
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Study Notes
Cardiorespiratory System: Part 2 - Respiratory System
- The respiratory system's primary function is gas exchange between the external environment and the body.
- Ventilation is the mechanical process of moving air in and out of the lungs.
- Diffusion is the random movement of molecules from an area of high concentration to an area of low concentration.
Learning Objectives
- Describe the structure and function of the respiratory system.
- Explain the mechanics of ventilation.
- Explain pulmonary volumes and capacities.
- Describe gas exchange, differentiating between internal and external respiration and explaining the ventilation-perfusion ratio.
- Summarize the processes for transporting respiratory gases.
- Explain the regulation of respiration.
Respiratory Structure: Bronchial Tree
- The conducting zone conducts air to the respiratory zone.
- Components of the conducting zone include the trachea, bronchial tree, and bronchioles, and they humidify, warm, and filter the air.
- The respiratory zone is where gas exchange occurs and includes respiratory bronchioles and alveolar sacs.
Conducting Zone: Mucociliary Clearance
- Mucociliary clearance is a primary innate defense mechanism in the lungs.
- Ciliated epithelial cells, a periciliary layer, and a mucus layer work together to remove particles.
- The ciliated lining and mucus layer trap foreign particles.
Cell Functions
- Ciliated epithelial cells move mucus in a metachronal rhythm to the pharynx.
- Goblet cells are principal secretory cells, secreting mucus.
- Serous and club cells secrete watery secretions.
Respiratory Zone
- The respiratory zone consists of gas exchange with blood.
- Surfactant production, immune function (macrophage), and clotting function are all functions of the respiratory zone.
- Alveoli are the smallest functional units for gas exchange.
- Type I alveolar cells for gas exchange and Type II cells release surfactant, preventing lung collapse.
Mechanics of Breathing
- Inspiration: the diaphragm pushes downward, reducing intrapulmonary pressure allowing air to enter the lungs.
- Expiration: the diaphragm relaxes, increasing intrapulmonary pressure, pushing air out of the lungs.
- Resistance to airflow is largely dependent on airway diameter.
Boyle's Law and Breathing
- Boyle's Law states that pressure of a gas is inversely related to volume.
- During inhalation, lung volume increases, reducing pressure, and drawing air into the lungs.
- During exhalation, lung volume decreases, increasing pressure, and expelling air from the lungs.
Sequence of Events: Inspiration/Expiration
- The process of breathing involves the following changes in the lungs due to muscle contractions and relaxation.
- Inspiration: Diaphragm descends, ribs elevate and thoracic volume increases, intrapulmonary pressure decreases, and air enters the lungs.
- Expiration: Diaphragm relaxes and ascends, ribs descend, thoracic volume decreases, intrapulmonary pressure increases and air leaves the lungs.
Ventilation: Pleurae
- The pleurae is a thin, double-layered serous membrane that divides the thoracic cavity.
- Parietal pleura lines the thoracic cavity walls.
- Visceral pleura covers the surface of the lungs.
- Pleural fluid fills the space between the pleurae and reduces friction during breathing.
Ventilation: Pressures
- Atmospheric pressure (Patm) is the external pressure surrounding the body which is 0 mm Hg..
- Intrapulmonary pressure (Ppul) is the pressure within the alveoli that fluctuates with breathing and equals zero when the lung is not changing volume.
- Intrapleural pressure (Pip) is the pressure within the pleural cavity. Pip will always be lower than Patm; normally -4 mm Hg.
Ventilation: Changes in Lung Volumes during Breathing
- Volume changes in the lungs during breathing are presented graphically.
- Changes in pressure are also shown in conjunction with volume changes in the lungs.
Pulmonary Ventilation
- Pulmonary ventilation (VE) is the amount of air moving in or out of the lungs per minute.
- It's calculated by multiplying tidal volume (VT) by breathing frequency (f).
- Normal ventilation values are also provided in a table
Ventilation
- Airflow is affected by airway resistance, alveolar surface tension, and lung compliance.
Ventilation: Airway Resistance
- Airway resistance primarily comes from friction during airflow.
- Flow changes are inversely proportional to resistance.
- Resistance in the conducting zone is determined in part by the diameters of the medium-sized bronchi.
Ventilation: Alveolar Surface Tension
- Water's high surface tension resists increased surface area at the gas-liquid interface of alveoli.
- Alveolar surfactant reduces surface tension by minimizing it.
Alveolar Surface Tension
- Surfactant is a detergent-like substance produced by Type II alveolar cells to reduce surface tension preventing lung collapse.
- Insufficient surfactant in premature infants may lead to infant respiratory distress syndrome.
Ventilation: Lung Compliance
- Lung compliance refers to the elasticity of lung tissue to stretch and expand, determined by surfactant production and tissue elasticity.
- Reduced surfactant production or lung tissue stiffness can diminish lung compliance.
Definition of Lung Volumes
- Lung volumes define different volumes of air in the lungs: tidal, inspiratory reserve, expiratory reserve, and residual.
Gas Exchange
- External respiration is the gas exchange that occurs in the lungs by diffusion.
- Internal respiration is the gas exchange that occurs at the tissue level by diffusion.
- Oxygen diffuses across alveolar and capillary membranes into the blood.
Gas Exchange: Constants and Variables
- Constant factors in gas exchange: surface area of gas, membrane permeability, membrane thickness, and diffusion distance.
- Variable factors in gas exchange: concentration and pressure gradients.
Gas Exchange: Physical Properties of Gas
- Gases (O2, CO2) move by simple diffusion along their partial pressure gradients until equilibrium is achieved. 2
Partial Pressure of Gases—Dalton's Law
- The total pressure of a gas mixture is the sum of the pressure each gas exerts independently.
- Partial pressure of oxygen (PO2) is calculated based on air composition and total pressure at sea level.
Gas Pressures in Atmosphere at Sea Level
- Atmospheric pressure at sea level is 760 mmHg.
- Values for partial pressures of oxygen, nitrogen, and carbon dioxide at sea level are shown.
External Respiration: Ventilation-Perfusion Coupling
- Ventilation is the amount of air carried into the alveoli. Perfusion is the amount of blood flow in the pulmonary capillaries.
- Ventilation and perfusion need to be balanced for optimal gas exchange.
External Respiration: Ventilation-Perfusion Mismatch
- V-Q mismatch occurs if ventilation and blood flow are not balanced in the alveoli. Causes include airway blockage or blood clots and it can result in hypoxemia and respiratory failure.
External Respiration: Ventilation- Perfusion Coupling
- V/Q mismatch can occur when ventilation is too high or low.
- Hypoxic vasoconstriction can shunt blood flow away from hypoxic areas to areas with high oxygen.
- Bronchoconstriction in areas of high V/Q ratio can reduce air flow to lung areas of low perfusion.
Gas Exchange: Internal Respiration
- Internal respiration involves a reversal of diffusion gradients compared to external respiration.
- Oxygen diffuses from the blood to the tissues, and carbon dioxide diffuses from the tissues to the blood.
Respiratory Gas Transport: O2 and Hb
- Oxygen is transported in the blood in two forms: dissolved and bound to hemoglobin.
- Hemoglobin binds oxygen in the lungs and releases it in tissues.
- Factors affecting oxygen binding and unloading include temperature, pH, partial pressures and 2,3-DPG.
Hb and O2 Carrying Capacity of Blood
- Hemoglobin and oxygen binding/carrying capacity values are shown for males, females, and other conditions such as blood doping and anemia.
Maximal Volume of O2 That Can Be Transported in Blood
- The maximal amount of O2 that can be transported depends on hemoglobin levels, oxygen carrying capacity, and hemoglobin saturation.
- An inequality in Ve/Q ratio produces limitations in the maximal blood oxygen level.
Oxygen Binding
- Factors influencing total oxygen content of arterial blood: inspired air composition, alveolar ventilation, airway resistance, lung compliance, oxygen diffusion, perfusion, surface area, membrane thickness and interstitial fluid quantity.
Respiratory Gas Exchange: Homeostatic Imbalance
- Hypoxia is a condition of decreased tissue oxygen and has various causes.
- Various types of hypoxia are distinguished by the mechanism of oxygen deficiency.
Carbon Dioxide Transport
- Carbon dioxide (CO2) is transported in the blood primarily as bicarbonate, which accounts for 70% of CO2.
- A chloride shift occurs in red blood cells during carbon dioxide transport.
- CO2 moves into the lungs for elimination from the body.
Respiratory Gas Exchange: Transport and Exchange of CO2
- CO2 moves into the lungs to be expelled from the body.
- The exchange of bicarbonate and chloride across the RBC membrane.
- Bicarbonate is transported in the blood to the lungs at the tissue level. CO2 transport is in two forms: dissolved and carried by hemoglobin.
Effect of Bicarbonate on Blood pH
- Bicarbonate is crucial in maintaining blood pH.
- Tissues can disrupt the equilibrium of bicarbonate ions via the carbonic acid-bicarbonate reaction during conditions of high metabolism. The blood buffer keeps pH levels within the proper range.
Control of Ventilation—Respiratory Control Center
- The respiratory center receives neural and humoral input, senses CO2 levels, and adjusts respiratory rate accordingly.
Regulation of Ventilation
- Peripheral chemoreceptors, located in the carotid and aortic bodies, sense changes in Po2, pH, and Pco2 to regulate respiration.
Carotid Body and Oxygen Sensor
- Carotid body oxygen sensors provide feedback to medullary centers to increase ventilation rates when Po2 decreases.
- Chemoreceptors in the carotid and aortic bodies trigger an increased respiratory rate to maintain the optimal balance of blood gases.
Central Chemoreceptors
- The central chemoreceptors monitor CO₂ in the cerebrospinal fluid (CSF).
- Increased CO₂ stimulates central chemoreceptors.
- Increased CO₂ stimulates ventilation rate.
Chemoreceptor Response to Changes in Plasma CO2
- Changes in plasma CO2 levels affect both central and peripheral chemoreceptors.
- Peripheral and central chemoreceptors stimulate a corresponding increase or decrease in ventilation to maintain the internal balance of respiratory gases.
Control of Respiration: Exercise
- During exercise, neural factors cause an increased ventilation rate to maintain constant CO2, Po2, and pH levels.
- Respiratory rate increases during exercise, but these three factors remain relatively constant. Breathing rate will decline back to normal during recovery.
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Description
Test your knowledge of the human respiratory system with this quiz focusing on gas exchange, the roles of different lung cells, and the mechanics of breathing. Answer questions about the respiratory zones, pressure changes, and the functions of surfactants and mucus. Perfect for biology students!
