The HeringBreuer inflation reflex is a response that is induced to prevent lung overinflation. It is named after Josef Breuer and Ewald Hering. Excessive lung stretching during heavy inspirations activates pulmonary stretch receptors, which are found on the walls of bronchi and bronchioles.
Once triggered, they send action potentials to the inspiratory area in the medulla and the apneustic center of the pons via long myelinated fibers of the vagus nerve.
The inspiratory area is directly blocked, and the apneustic center is prevented from activating the inspiratory area as a result. This prevents inspiration and allows for expiration.
The inflation reflex identified by Hering and Breuer should not be confused with the deflation reflex discovered by the same individuals.
The inflation reflex is discussed for the most part on this page; the deflation reflex is discussed separately at the conclusion.
What is the mechanism of the inflation reflex?
Lung expansion triggers the Hering-Breuer response, which activates stretch receptors in the airways. The vagus nerve sends signals to these receptors, which decrease inspiratory durations as tidal volume (the volume of air inhaled) increases, causing breathing to become more frequent.
What causes the breathing reflex?
The central and peripheral chemoreceptors, as well as pulmonary stretch receptors, a kind of mechanoreceptor, play key roles in the regulation of respiration.
- The central nervous system’s central chemoreceptors, which are positioned on the ventrolateral medullary surface, are sensitive to the pH of their surroundings.
- In addition to sensing arterial PCO2 and pH, peripheral chemoreceptors are most significant for detecting variations in PO2 in the arterial blood.
- The airways and parenchyma contain mechanoreceptors, which are responsible for a range of reflex responses. These are some of them:
- Coughing, airway constriction, and hyperventilation are all reflex responses to the Hering-Breuer reflex, which stops inhalation to prevent overinflation of the lungs.
- Sneezing, coughing, glottis closure, and hiccups are all reflex responses triggered by upper airway receptors.
- The activation of additional respiratory muscles as compensation, a gasping reaction, hypoventilation, and an increase in breathing frequency and volume are all examples of spinal cord reflex responses.
- By deepening the inhale, the nasopulmonary and nasothoracic reflexes regulate the breathing system. Impulses from the nasal mucosa are transmitted by the trigeminal nerve to the respiratory center in the brainstem, and the generated response is transmitted to the bronchi, the intercostal muscles, and the diaphragm, all of which are triggered by the flow of air, the pressure of the air in the nose, and the quality of the air.
- Head’s paradoxical reflex, in which a momentary respiratory effort or gasp is caused by abrupt lung inflation.
What protects your lungs from ballooning too much?
Simply explained, the Hering-Breuer reaction prevents the lungs from over-inflating with inspired air. The HeringBreuer inflation reflex is controlled by a neuronal circuit that includes many parts of the central nervous system, as well as sensory and motor components of the vagus nerve.
Increased sensory activity of the pulmonary-stretch lung afferents (through the vagus nerve) inhibits the central inspiratory drive, preventing inspiration and causing expiration to begin. The cardiac vagal motor neurones (CVM) in the nucleus ambiguus (NA) and dorsal motor vagal nucleus (DMVN) receive inhibitory projections from the lung afferents (DMVN). Tonic inhibitory control of heart rate is controlled by CVMs, which send motor fibers to the heart via the vagus nerve. As a result, an increase in pulmonary stretch receptor activity causes CVM inhibition and an increase in heart rate (tachycardia). This is known as sinus arrhythmia, and it is a common occurrence in healthy people.
How does the brain prevent overinflation of the lungs?
The vagus nerve has cardiac and respiratory branches. The vagus nerve is the neurological mechanism for stretch receptor breathing regulation.
The HeringBreuer reaction (also known as the inflation reflex) is activated to prevent the lungs from overinflating. When the lungs have inflated to their optimal maximum point, many stretch receptors in the lungs, particularly in the pleura and the smooth muscles of the bronchi and bronchioles, activate.
Mechanoreceptors, a type of sensory receptor that detects mechanical pressure, distortion, and stretch, are found in numerous regions of the human body, including the lungs, stomach, and skin. They don’t register fine-tactile information like other sensory receptors in the human body, but when triggered, they provide a sense of tension or fullness, particularly in the lungs and stomach.
The pulmonary stretch receptors deliver an action potential signal to the medulla and pons in the brain when the lungs are inflated to their maximum volume during inhalation.
The pons’ pneumotaxic center sends signals to the apneustic center to prohibit it from activating the inspiratory area (the dorsal medulla), and the inspiratory impulses to the diaphragm and accessory muscles stop. The inflation reflex is the name for this phenomenon.
Expiration begins as soon as inspiration ends, and the lung begins to collapse. The stretch receptors in the lungs are deactivated (and compression receptors termed proprioreceptors may be engaged) as the lungs deflate, allowing the inhibitory signals to stop and inhalation to resumethis is known as the deflation reflex.
This reflex was thought to have a vital role in determining the rate and depth of breathing in humans by early physiologists. While this is true for most animals, it is not true for the majority of adult humans while they are at rest. When the tidal volume is greater than 1 L, such as when exercising, the reflex may dictate the breathing rate and depth in babies and adults.
Furthermore, because of the lack of pulmonary stretch receptors caused by lung tissue death, persons with emphysema have an impaired HeringBauer reflex, which causes their lungs to over-inflate and collapse, contributing to shortness of breath.
Which of the following statements about the inflation reflex is correct? The inflation reflex ensures that the lungs inflate sufficiently during forceful inhalation.
Which of the following assertions is ACTUALLY TRUE? During forceful inhalation, the inflation reflex ensures that the lungs are sufficiently inflated. The strongest physiologic stimulus for increased respiration is a drop in blood oxygen levels. Hyperventilation is the proper physiologic response to hypercapnia.
How can hypercapnia develop?
Hypoventilation or disorganized breathing, in which not enough oxygen enters the lungs and not enough carbon dioxide is released, is a common cause. Hypercapnia can be caused by a variety of factors, including various lung disorders.
The signs and symptoms of hypercapnia can range from moderate to severe. Hypercapnia can be caused by a variety of factors.
The signs and causes of hypercapnia are discussed in this article, as well as some therapeutic options for managing the illness.
Why is the vagus nerve suppressed during inspiration?
It is known that when the vagus trunk is activated, afferene fibers not of pulmonary origin may have an inhibitory influence on breathing (e.g., from pressure receptors in the aorta). The electrodes were placed 4 to 8 cm below the superior laryngeal branch’s origin.
What is the definition of hypercapnia?
- This is usually caused by the body’s hypoventilation, which results in CO2 retention.
- On Arterial Blood Gas measurements, hypercapnia is defined as a partial pressure of carbon dioxide (PaCO2) greater than 45 mm Hg.
- Long-term hypoxia can create hypercapnia, which leads the body to compensate, resulting in a rise in CO2 in the blood. Type 2 respiratory failure is the name for this condition.
The pulmonary system is usually very effective at removing excess CO2. The failure of the pulmonary system to appropriately breathe and remove CO2 is the most common cause of hypercapnia.
- BiPAP, CPAP, and intubation with mechanical ventilation are supportive treatments that try to improve oxygenation while eliminating CO2 from the body, but hypercapnia treatment should focus on diagnosing the etiology and tailoring therapy to it.