Podcast
Questions and Answers
Which of the following best describes the primary function of the Pontine Respiratory Group (PRG)?
Which of the following best describes the primary function of the Pontine Respiratory Group (PRG)?
- Directly controlling the contraction of intercostal muscles.
- Generating the basic rhythmic cycle of breathing.
- Initiating inspiration by stimulating the diaphragm.
- Constantly inhibiting medullary centers to smooth out inspiration. (correct)
The skeletal muscles responsible for breathing can contract spontaneously, similar to autorhythmic cardiac muscle.
The skeletal muscles responsible for breathing can contract spontaneously, similar to autorhythmic cardiac muscle.
False (B)
What are the three major factors sensed by chemoreceptors that influence a person's ventilation pattern?
What are the three major factors sensed by chemoreceptors that influence a person's ventilation pattern?
CO2, O2, and H+
Central chemoreceptors primarily respond to changes in blood gas levels by detecting changes in ______ concentration in the cerebrospinal fluid.
Central chemoreceptors primarily respond to changes in blood gas levels by detecting changes in ______ concentration in the cerebrospinal fluid.
Match the following respiratory groups with their primary function:
Match the following respiratory groups with their primary function:
Which of the following stimuli would lead to an increased rate of breathing?
Which of the following stimuli would lead to an increased rate of breathing?
Central chemoreceptors respond more quickly to changes in blood $CO_2$ levels compared to peripheral chemoreceptors.
Central chemoreceptors respond more quickly to changes in blood $CO_2$ levels compared to peripheral chemoreceptors.
What is the role of the Hering-Breuer reflex in the control of breathing?
What is the role of the Hering-Breuer reflex in the control of breathing?
Peripheral chemoreceptors are especially sensitive to changes in arterial $P_{O_2}$ when it falls below ______ mmHg.
Peripheral chemoreceptors are especially sensitive to changes in arterial $P_{O_2}$ when it falls below ______ mmHg.
Match the brain area with its role in respiration
Match the brain area with its role in respiration
Which of the following is the primary function of the dorsal respiratory group (DRG)?
Which of the following is the primary function of the dorsal respiratory group (DRG)?
An increase in arterial pH will stimulate an increase in respiration rate.
An increase in arterial pH will stimulate an increase in respiration rate.
What is the main function of pulmonary irritant reflexes?
What is the main function of pulmonary irritant reflexes?
The ______ in the carotid arteries and aorta are sensitive to changes in arterial $P_{O_2}$, $P_{CO_2}$, and pH.
The ______ in the carotid arteries and aorta are sensitive to changes in arterial $P_{O_2}$, $P_{CO_2}$, and pH.
Which of the following best describes the location of central chemoreceptors?
Which of the following best describes the location of central chemoreceptors?
Flashcards
Brain regions controlling breathing
Brain regions controlling breathing
Brain regions responsible for controlling breathing include the medulla oblongata, pons, hypothalamus, and cerebral cortex.
Dorsal Respiratory Group (DRG)
Dorsal Respiratory Group (DRG)
The Dorsal Respiratory Group (DRG) is the inspiratory center, stimulating the diaphragm and intercostals, generating a rhythmic cycle.
Ventral Respiratory Group (VRG)
Ventral Respiratory Group (VRG)
The Ventral Respiratory Group (VRG) is involved in forced inspiration and expiration.
Pontine Respiratory Group (PRG)
Pontine Respiratory Group (PRG)
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Chemoreceptors
Chemoreceptors
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Peripheral Chemoreceptors
Peripheral Chemoreceptors
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Central Chemoreceptors
Central Chemoreceptors
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Pulmonary Irritant Reflexes
Pulmonary Irritant Reflexes
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Inflation Reflex
Inflation Reflex
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Movement affecting respiration
Movement affecting respiration
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Effect of holding breath
Effect of holding breath
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Location of peripheral chemoreceptors
Location of peripheral chemoreceptors
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Automatic vs. Voluntary Control
Automatic vs. Voluntary Control
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Hypothalamus Role
Hypothalamus Role
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Cerebral Cortex Role
Cerebral Cortex Role
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Study Notes
Regulation of Ventilation
- Breathing, like the beating heart, can occur without conscious thought
- Unlike autorhythmic muscles, skeletal muscles that control breathing are unable to spontaneously contract
- Breathing is controlled both automatically and voluntarily
- Three major factors sensed by chemoreceptors influence a person's ventilation pattern include: CO2, O2, and H+ concentration in the brain and periphery
Control of Ventilation: Complex
- Central and peripheral chemoreceptors monitor blood gasses and pH
- Control networks in the brain stem regulate activity in somatic motor neurons, leading to respiratory muscles
The Medullary Centres
- Dorsal Respiratory Group (DRG) functions as the inspiratory centre
- It stimulates the phrenic and intercostal nerves connected to the diaphragm and intercostals
- DRG generates a rhythmic breathing cycle
- Input from vagal and glossopharyngeal nerves also affects DRG
- Ventral Respiratory Group (VRG) is involved in forced inspiration and expiration
- Pontine Respiratory Group (PRG) constantly inhibits responses by the medullary centres to smooth out inspiration
Afferent Input to Medullary Centres
- Respiratory centres existing in the medulla and pons receive input from:
- Higher brain centres
- Other receptors for pain
- Peripheral chemoreceptors
- Central chemoreceptors
- Stretch receptors in the lungs
- Irritant receptors
- Receptors in muscles and joints
Peripheral Chemoreceptors
- Peripheral chemoreceptors respond quickly to changes
- They are located in the carotid arteries and aorta
- Peripheral chemoreceptors sense changes in O2, pH, and CO2
- Glomus cells in the carotid arteries and aorta are specialized cells that sense these changes
- Peripheral chemoreceptors are very sensitive to changes in pCO2 and pH
- They are much less sensitive to changes in pO2, which must fall below 60mmHg
- Peripheral chemoreceptors are important for hypoxic conditions (decrease in PO2) such as during chronic exhaustive endurance exercise or at high altitude
- They also play a role in minute-to-minute breathing changes (increase in pCO2) like when breath-holding, leading to a ventilatory drive due to increased pCO2
Central Chemoreceptors
- Central chemoreceptors respond slowly to changes
- They respond to pCO2 levels
- CO2 diffuses readily across the blood-brain barrier
- Increased H+ signals ventilation changes
Higher Centres
- Hypothalamus impacts respiration: Strong emotions, pain, and stress result in activation of the SNS, altering respiration
- Cerebral Cortex impacts respiration: Controls voluntary breathing
Control of Breathing
- Pulmonary irritant reflexes: They involve lung receptors responding to a variety of irritants, stimulating the vagal nerve resulting in coughing or sneezing
- Inflation Reflex:
- This is known as the Hering-Breur Reflex
- Stretch receptors in the bronchiole walls are activated to switch off inspiration
Ventilation Feedback Mech
- Increased arterial PCOâ‚‚ and pH in cerebrospinal fluid stimulates ventilation
- Central chemoreceptors in the medulla mediate 70% of the response, while peripheral chemoreceptors in the carotid and aortic bodies mediate 30% of the response
- This leads to increased alveolar ventilation and more CO2 exhaled
- Arterial PCOâ‚‚ and pH will return to normal levels
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