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Questions and Answers
If a person were to inhale the maximum amount of air possible after a normal inhalation, what volume would this be considered?
If a person were to inhale the maximum amount of air possible after a normal inhalation, what volume would this be considered?
Which respiratory volume is the amount of air that remains in the lungs even after a forceful exhalation?
Which respiratory volume is the amount of air that remains in the lungs even after a forceful exhalation?
A patient with a lung disease has difficulty breathing out after a normal exhalation. Which respiratory volume is likely affected?
A patient with a lung disease has difficulty breathing out after a normal exhalation. Which respiratory volume is likely affected?
A healthy individual takes a normal breath, what is the volume of air typically inhaled?
A healthy individual takes a normal breath, what is the volume of air typically inhaled?
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During strenuous exercise, the body's demand for oxygen increases. Which respiratory volume would likely increase to meet this demand?
During strenuous exercise, the body's demand for oxygen increases. Which respiratory volume would likely increase to meet this demand?
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A patient with a lung disease has a significantly reduced ability to exhale forcefully. Which respiratory volume would be most affected by this condition?
A patient with a lung disease has a significantly reduced ability to exhale forcefully. Which respiratory volume would be most affected by this condition?
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What is the main function of alveolar ventilation?
What is the main function of alveolar ventilation?
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What is the effect of an increase in temperature on hemoglobin saturation?
What is the effect of an increase in temperature on hemoglobin saturation?
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What is the effect of an increase in carbon dioxide levels on hemoglobin saturation?
What is the effect of an increase in carbon dioxide levels on hemoglobin saturation?
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What is the primary way that carbon dioxide is transported in the blood?
What is the primary way that carbon dioxide is transported in the blood?
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What is the effect of hypoxia on oxygen delivery to the tissues?
What is the effect of hypoxia on oxygen delivery to the tissues?
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What is the function of the Bohr effect?
What is the function of the Bohr effect?
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What is the effect of ventilation-perfusion coupling on gas exchange?
What is the effect of ventilation-perfusion coupling on gas exchange?
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What is the effect of an increase in BPG levels on hemoglobin saturation?
What is the effect of an increase in BPG levels on hemoglobin saturation?
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What is the function of the respiratory membrane?
What is the function of the respiratory membrane?
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What is the effect of an increase in hemoglobin concentration on oxygen delivery to the tissues?
What is the effect of an increase in hemoglobin concentration on oxygen delivery to the tissues?
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What is the main function of the Dorsal Respiratory Group (DRG)?
What is the main function of the Dorsal Respiratory Group (DRG)?
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What is the primary role of the Pontine Respiratory Centers?
What is the primary role of the Pontine Respiratory Centers?
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Which of the following is NOT a chemical factor influencing the depth and rate of breathing?
Which of the following is NOT a chemical factor influencing the depth and rate of breathing?
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How does an increase in Pco2 levels stimulate the respiratory centers?
How does an increase in Pco2 levels stimulate the respiratory centers?
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What is the primary function of the Hering-Breuer reflex?
What is the primary function of the Hering-Breuer reflex?
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Which of the following conditions is characterized by an irreversible decrease in the ability to force air out of the lungs?
Which of the following conditions is characterized by an irreversible decrease in the ability to force air out of the lungs?
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What is the primary cause of lung cancer in 90% of cases?
What is the primary cause of lung cancer in 90% of cases?
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Which of the following is NOT a characteristic symptom of asthma?
Which of the following is NOT a characteristic symptom of asthma?
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What is the most powerful respiratory stimulant?
What is the most powerful respiratory stimulant?
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How do the higher brain centers influence breathing?
How do the higher brain centers influence breathing?
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What happens to carbon dioxide when it reacts with water in plasma?
What happens to carbon dioxide when it reacts with water in plasma?
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What is the term for the amount of air that always remains in the lungs?
What is the term for the amount of air that always remains in the lungs?
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What is the term for the total amount of air the lungs can hold?
What is the term for the total amount of air the lungs can hold?
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What happens to hydrogen ions in the blood?
What happens to hydrogen ions in the blood?
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What is the term for the amount of air forcefully exhaled after deepest inhalation possible?
What is the term for the amount of air forcefully exhaled after deepest inhalation possible?
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What is formed when carbon dioxide combines with hemoglobin?
What is formed when carbon dioxide combines with hemoglobin?
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What is the term for the amount of air that moves during a normal breath?
What is the term for the amount of air that moves during a normal breath?
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What is the result of the ionization of carbonic acid?
What is the result of the ionization of carbonic acid?
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Which of the references are NOT authored by an individual?
Which of the references are NOT authored by an individual?
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Which reference is the most recent, according to the provided information?
Which reference is the most recent, according to the provided information?
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Which reference has a clear indication of being part of a series or multiple parts?
Which reference has a clear indication of being part of a series or multiple parts?
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Which reference explicitly uses a date format that is NOT a year?
Which reference explicitly uses a date format that is NOT a year?
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Which references could be considered outdated based on the publication dates provided?
Which references could be considered outdated based on the publication dates provided?
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Which reference is NOT directly linked to an educational institution?
Which reference is NOT directly linked to an educational institution?
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Study Notes
Respiratory Volumes
- Tidal Volume (TV): 500 ml, volume inspired or expired with each normal breath
- Inspiratory Reserve Volume (IRV): 3100 ml, maximum volume that can be inspired over the inspiration of a tidal volume/normal breath
- Expiratory Reserve Volume (ERV): 1200 ml, maximal volume that can be expired after the expiration of a tidal volume/normal breath
- Residual Volume (RV): 1200 ml, volume that remains in the lungs after a maximal expiration, cannot be measured by spirometry
Respiratory Capacities
- Inspiratory Capacity (IC): 3600 ml, volume of maximal inspiration (IRV + TV)
- Functional Residual Capacity (FRC): 2400 ml, volume of gas remaining in lung after normal expiration, cannot be measured by spirometry because it includes residual volume (ERV + RV)
- Vital Capacity (VC): 4800 ml, volume of maximal inspiration and expiration (IRV + TV + ERV)
- Total Lung Capacity (TLC): 6000 ml, the volume of the lung after maximal inspiration, sum of all four lung volumes (IRV + TV + ERV + RV)
Dead Space
- Anatomical dead space: volume of the conducting zone conduits (~150 ml)
- Alveolar dead space: alveoli that cease to act in gas exchange due to collapse or obstruction
- Total dead space: sum of above non-useful volumes
Pulmonary Function Tests
- Spirometer: instrument used to measure respiratory volumes and capacities
- Minute ventilation: total amount of gas flow into or out of the respiratory tract in one minute
- Forced vital capacity (FVC): gas forcibly expelled after taking a deep breath
- Forced expiratory volume (FEV): the amount of gas expelled during specific time intervals of the FVC
Alveolar Ventilation
- Alveolar ventilation rate (AVR): flow of gases into and out of the alveoli during a particular time
- AVR = frequency X (TV – dead space)
Nonrespiratory Air Movements
- Examples: cough, sneeze, crying, laughing, hiccups, and yawns, most result from reflex action
Gas Exchanges Between Blood, Lungs, and Tissues
- External respiration: exchange of O2 and CO2 across the respiratory membrane
- Internal respiration: capillary gas exchange in body tissues
Basic Properties of Gases
- Dalton’s Law of Partial Pressures: total pressure exerted by a mixture of gases is the sum of the pressures exerted by each gas
- Henry’s Law: the partial pressure of each gas in a mixture is directly proportional to its percentage in the mixture
Composition of Alveolar Gas
- Alveolar gas contains more CO2 and water vapor than atmospheric air, due to gas exchanges in the lungs, humidification of air, and mixing of alveolar gas that occurs with each breath
External Respiration
- Influenced by partial pressure gradients and gas solubility
- Ventilation-perfusion coupling: amount of gas reaching the alveoli (ventilation) and blood flow reaching the alveoli (perfusion) must be matched for efficient gas exchange
Ventilation-Perfusion Coupling
- Changes in Po2 in the alveoli cause changes in the diameters of the arterioles
- Changes in Pco2 in the alveoli cause changes in the diameters of the bronchioles
Transport of Oxygen and Carbon Dioxide in the Blood
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Oxygen transport: 1.5% dissolved in plasma, 98.5% loosely bound to each Fe of hemoglobin (Hb) in RBCs, 4 O2 per Hb
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Carbon dioxide transport: 7 to 10% dissolved in plasma, 20% bound to globin of hemoglobin (carbaminohemoglobin), 70% transported as bicarbonate ions (HCO3–) in plasma### Respiratory System
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The dorsal respiratory group (DRG) is located near the root of cranial nerve IX and integrates input from peripheral stretch and chemoreceptors.
Medullary Respiratory Centers
- The ventral respiratory group (VRG) is the rhythm-generating and integrative center that sets eupnea (12-15 breaths/minute).
- Inspiratory neurons in the VRG excite the inspiratory muscles via the phrenic and intercostal nerves.
- Expiratory neurons in the VRG inhibit the inspiratory neurons.
Pontine Respiratory Centers
- The pontine respiratory centers interact with the medullary respiratory centers to smooth out the respiratory pattern.
- The pontine respiratory centers influence and modify the activity of the VRG.
Genesis of Respiratory Rhythm
- The genesis of the respiratory rhythm is not well understood, but the most widely accepted hypothesis is that it is due to reciprocal inhibition of two sets of interconnected neuronal networks in the medulla.
Depth and Rate of Breathing
- The depth of breathing is determined by how actively the respiratory center stimulates the respiratory muscles.
- The rate of breathing is determined by how long the inspiratory center is active.
- Both depth and rate are modified in response to changing body demands.
Chemical Factors
- Rising CO2 levels stimulate the respiratory center to increase the depth and rate of breathing.
- Hyperventilation leads to a decline in CO2 levels, which can cause cerebral vasoconstriction and cerebral ischemia.
- A drop in Po2 levels below 60 mm Hg stimulates the peripheral chemoreceptors to increase ventilation.
- Changes in pH levels can modify respiratory rate and rhythm even if CO2 and O2 levels are normal.
Brain Centers and Reflexes
- The hypothalamus acts through the limbic system to modify the rate and depth of respiration.
- Cortical controls are direct signals from the cerebral motor cortex that bypass medullary controls.
- Pulmonary irritant reflexes promote reflexive constriction of air passages and cough and sneeze reflexes.
- The Hering-Breuer reflex is a protective response that inhibits inhalation and allows expiration to occur.
Homeostatic Imbalances
- Chronic obstructive pulmonary disease (COPD) is exemplified by chronic bronchitis and emphysema, which lead to irreversible damage to the lungs.
- Asthma is characterized by coughing, dyspnea, wheezing, and chest tightness due to airway inflammation and bronchospasms.
- Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, which can lead to lung damage and respiratory failure.
- Lung cancer is the leading cause of cancer deaths in North America, often caused by smoking.
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Description
Learn about the respiratory system, including respiratory volumes and capacities, internal and external respiration, oxygen and carbon dioxide transport, and brain control of breathing patterns.
