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Questions and Answers
What is the formula for partial pressure?
What is the formula for partial pressure?
Which factor does NOT affect the diffusion rate of O2 into the blood?
Which factor does NOT affect the diffusion rate of O2 into the blood?
How does high altitude affect alveolar PO2?
How does high altitude affect alveolar PO2?
What can cause a decrease in the functional surface area of the respiratory membrane?
What can cause a decrease in the functional surface area of the respiratory membrane?
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Which of the following can reduce the respiratory minute volume?
Which of the following can reduce the respiratory minute volume?
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What is the primary form in which CO2 is carried in the blood?
What is the primary form in which CO2 is carried in the blood?
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What role does carbonic anhydrase play in CO2 transport?
What role does carbonic anhydrase play in CO2 transport?
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How does the addition of protons (H+) affect blood pH?
How does the addition of protons (H+) affect blood pH?
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What happens to the oxygen content in venous blood compared to arterial blood?
What happens to the oxygen content in venous blood compared to arterial blood?
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What is the chloride shift in the context of CO2 transport?
What is the chloride shift in the context of CO2 transport?
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What initiates compensatory responses in peripheral receptors related to acid-base balance?
What initiates compensatory responses in peripheral receptors related to acid-base balance?
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In which condition will peripheral chemoreceptors NOT be stimulated?
In which condition will peripheral chemoreceptors NOT be stimulated?
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At what arterial PO2 range does a dramatic increase in ventilation occur?
At what arterial PO2 range does a dramatic increase in ventilation occur?
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How does the hypoxic drive sensitivity change in response to arterial PCO2 levels?
How does the hypoxic drive sensitivity change in response to arterial PCO2 levels?
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What might oxygen administration lead to in COPD patients concerning hypoxic drive?
What might oxygen administration lead to in COPD patients concerning hypoxic drive?
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What is the role of chemoreceptors in the regulation of breathing?
What is the role of chemoreceptors in the regulation of breathing?
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Where are central chemoreceptors primarily located?
Where are central chemoreceptors primarily located?
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What initiates the formation of carbaminohemoglobin in tissues?
What initiates the formation of carbaminohemoglobin in tissues?
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Which of the following best describes the normal range for arterial PCO2?
Which of the following best describes the normal range for arterial PCO2?
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What happens to ventilation when PCO2 levels decrease below 35 mm Hg?
What happens to ventilation when PCO2 levels decrease below 35 mm Hg?
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What is the primary function of the integrators located in the brainstem regarding respiration?
What is the primary function of the integrators located in the brainstem regarding respiration?
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What effect does hypercapnia have on ventilation?
What effect does hypercapnia have on ventilation?
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Which structures are involved in the detection of blood chemistry changes due to their perfusion?
Which structures are involved in the detection of blood chemistry changes due to their perfusion?
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What effect does extreme hypoxia have on the respiratory centres?
What effect does extreme hypoxia have on the respiratory centres?
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How does hypoxic pulmonary vasoconstriction (HPV) affect blood flow in the lungs?
How does hypoxic pulmonary vasoconstriction (HPV) affect blood flow in the lungs?
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What is the primary response of baroreceptors to a sudden rise in arterial pressure?
What is the primary response of baroreceptors to a sudden rise in arterial pressure?
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What initiates the Hering-Breuer reflex?
What initiates the Hering-Breuer reflex?
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What is one factor that can modify normal breathing rhythms?
What is one factor that can modify normal breathing rhythms?
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What can result from sudden painful stimulation in terms of respiratory response?
What can result from sudden painful stimulation in terms of respiratory response?
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What role does low arterial blood pH play in hypoxic pulmonary vasoconstriction?
What role does low arterial blood pH play in hypoxic pulmonary vasoconstriction?
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Which statement about hyperoxia and pulmonary vasculature in normal lungs is accurate?
Which statement about hyperoxia and pulmonary vasculature in normal lungs is accurate?
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What is the primary regulator of ventilation as identified by central chemoreceptors?
What is the primary regulator of ventilation as identified by central chemoreceptors?
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How do central chemoreceptors indirectly respond to CO2 levels?
How do central chemoreceptors indirectly respond to CO2 levels?
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Why does pH change quickly in the cerebrospinal fluid (CSF)?
Why does pH change quickly in the cerebrospinal fluid (CSF)?
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Under normal conditions, how does ventilation affect PaO2 levels?
Under normal conditions, how does ventilation affect PaO2 levels?
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Which statement is true regarding the response of peripheral chemoreceptors?
Which statement is true regarding the response of peripheral chemoreceptors?
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What occurs with chronically elevated PCO2 in conditions such as COPD?
What occurs with chronically elevated PCO2 in conditions such as COPD?
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What distinguishes central chemoreceptors from peripheral chemoreceptors in terms of CO2 response?
What distinguishes central chemoreceptors from peripheral chemoreceptors in terms of CO2 response?
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What effect does the blood-brain barrier have on central chemoreceptors?
What effect does the blood-brain barrier have on central chemoreceptors?
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Study Notes
Respiratory Physiology Overview
- Specific processes include ventilation (a mechanical process), gas exchange (external and internal respiration) at the lungs and body tissues, gas transport in the blood (circulatory), and regulation of respiratory function (autonomic and somatic).
Physics of Ventilation
- Air, as a fluid, behaves according to physical principles.
- Gases move from high to low pressure regions.
- Normal atmospheric pressure is 760 mmHg.
- Inspiration occurs when alveolar pressure is less than atmospheric pressure.
- Expiration occurs when alveolar pressure is greater than atmospheric pressure.
Ventilation Mechanics (Inspiration)
- The diaphragm and external intercostals contract, enlarging the thoracic cavity.
- This decreases intra-alveolar pressure, drawing air into the lungs.
Ventilation Mechanics (Expiration)
- Relaxation of inspiratory muscles increases intra-alveolar pressure, forcing air out of the lungs.
Lung Volumes
- Tidal volume (TV): Air exhaled after normal inspiration (~500 mL)
- Inspiratory reserve volume (IRV): Air that can be forcibly inhaled after normal inspiration (~3300 mL).
- Expiratory reserve volume (ERV): Air that can be forcibly exhaled after normal expiration (~1200 mL)
- Residual volume (RV): Air left in the lungs after maximal exhalation (~1200 mL).
Pulmonary Capacities
- Vital capacity (VC): Maximum volume of air that can be moved in and out of the lungs (TV + IRV + ERV).
- Inspiratory capacity (IC): Maximum volume that can be inspired after normal expiration (TV + IRV).
- Functional residual capacity (FRC): Volume remaining after normal expiration (ERV + RV).
- Total lung capacity (TLC): Total volume of air the lungs can hold (TV + IRV + ERV + RV).
Dead Space
- Only air entering the respiratory zone participates in gas exchange.
- Anatomical dead space is the volume of air in the conducting passages.
- Physiological dead space includes anatomical dead space and any alveolar space that's not perfused (blood flow).
Partial Pressures
- Dalton's Law relates gas concentration and partial pressure in a mixture.
- Partial pressures in air and liquid (blood) determine direction of gas flow (from high to low pressure).
- Atmospheric PO2 is about 159.6 mmHg, Alveolar PO2 is 100mmHg, and Venous PO2 is 37mmHG.
Pulmonary Gas Exchange
- Gases move across respiratory membranes down their respective pressure gradients(O2 from alveolar air to blood, and CO2 from blood to alveolar air).
- The rate of O2 diffusion is determined by several factors including: the PO2 gradient between alveolar air and blood; functional surface area of the respiratory membrane; respiratory minute volume, and alveolar ventilation.
Oxygen Transport
- Hemoglobin (Hb) transports oxygen and carbon dioxide within red blood cells.
- Each Hb molecule can carry up to four oxygen molecules. -Oxygen in the plasma is only a small amount. Most is carried as HbO2 in the red blood cells.
- Oxygen content of blood depends on the Hb concentration.
Oxygen Transport (Oxyhemoglobin Curve)
- The oxyhemoglobin dissociation curve shows the relationship between blood oxygen concentration and the partial pressure of oxygen.
- Oxygen's loading and unloading varies along the curve. Increased PO2 causes rapid oxygen loading.
Carbon Dioxide Transport
- Carbon dioxide is transported in the blood: Dissolved in the plasma. Bound to hemoglobin (carbaminohemoglobin) As bicarbonate ions.
Chemical Control of Respiration
- Chemoreceptors detect changes in blood chemistry (pH and gas levels).
- Central chemoreceptors in the medulla respond to changes in hydrogen ion concentration in cerebrospinal fluid (CSF) caused by changes in arterial CO2.
- Peripheral chemoreceptors in carotid and aortic bodies respond to changes in arterial PO2, PCO2, and pH
Hypoxic Drive
- Hypoxia induces an increase in ventilation (increased firing rate by chemoreceptors). This increase in drive is exacerbated if CO2 levels are also elevated.
Vascular Resistance and Flow
- Alveolar oxygen tension has a direct influence on the blood vessels supplying those alveoli.
- Reduced inspired PO2 (hypoxia) results in vasoconstriction of arterioles supplying the alveolar regions (hypoxic pulmonary vasoconstriction).
Blood Pressure and the Hering-Breuer Reflex
- Changes in arterial pressure affect the respiratory rate via aortic and carotid baroreceptors.
- The Hering-Breuer reflex involves stretch receptors in the lungs that inhibit the inspiratory center as the lungs expand.
Other Factors
- Voluntary impulses from the cerebral cortex can modify normal breathing rhythms.
- Reflexive acute apnea can result from various stimuli, including sudden pain, cold exposure, and irritation of the larynx or pharynx.
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Description
Test your understanding of key concepts in respiratory physiology, including ventilation mechanics, gas exchange, and lung volumes. This quiz covers both the physical principles of respiration and the processes involved in inspiration and expiration.
