Regulation of Respiration – Class 11 | Chapter – 17 | Biology Short Notes Series PDF

Regulation of Respiration: The ability of humans to control or regulate their breathing rhythm to meet their body’s needs is significantly known as the regulation of respiration. The complex interaction of three respiratory system parts. 

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  • the control centres, 
  • the sensors, 
  • the effector organs—is essential for controlling breathing. The brainstem is home to the control centres, which are in charge of breathing’s automaticity.

Regulation of Respiration Types

There are two mechanisms that can control breathing.

  • Neural regulation: Respiratory centres located in the medulla oblongata are part of the nervous system that controls breathing. It measures the blood’s level of oxygen and carbon dioxide and uses the respiratory muscles to provide the appropriate signals. More specifically, there are two categories of respiratory centres.
  • Chemical regulation: Centres associated with the chemical regulation of respiration are as follows:
    • Central chemoreceptors:
      •  These can be found in the area of the medullary oblongata close to the inspiratory centre. 
      • The concentration of pCO2 and H+ ions affects this region. Therefore, a rise in pCO2 and H+ ions activates these receptors, which in turn activates the inspiratory centre or the respiratory rhythm centre. 
      • The rate of inspiration or respiration is altered when rhythm centres are active. As a result, the respiratory system will need to change in order to clear these pollutants.
    • Peripheral chemoreceptors:
      • In hypoxemia, peripheral chemoreceptors detect changes in arterial blood oxygen levels and trigger reflexes that are essential for maintaining homeostasis.
      • peripheral chemoreceptor responses are important because of how they react to various pathological and physiological situations.
      • Both the carotid and aortic bodies experience an increase in sensory discharge in response to hypoxia.
      • It has been shown that the carotid bodies, the main peripheral chemoreceptor, are more responsible for the hypoxic response.

Regulation of Respiration

Respiration is modulated by neural impulses that travel from the brain’s respiratory centres to the muscles of the chest and diaphragm. The three major brain centres that control respiration are, they can be found in the pons and medulla of the brain. They stimulate the diaphragm and intercostal muscles to contract, which controls breathing.

In Medulla

Respiratory Rhythm Center

The pneumotaxic centre, which controls how well the respiratory rhythm centre works, is located in the pons, while the respiratory rhythm centre is located in the medulla oblongata.
The inspiration centre in the medulla, which controls the dorsal respiratory rhythm, is primarily in charge of maintaining a normal breathing rhythm.
When engaging in physical activity that results in deep breathing, the ventral respiratory centre of the medulla (expiratory centre) is in charge of sending signals to control the rhythm of both expiration and inspiration.

In Pons

Pneumotaxic Centre

The upper pons contains the pneumotaxic centre, which controls inspiratory volume and respiratory rate by sending inhibitory impulses to the inspiratory centre and shopping inspiration. This centre is probably important in fine-tuning breathing.

Apneustic Centre

The inspiratory centre is hypothesised to be stimulated by the lower pons’ apneustic centre. Stimulation of the apneustic centre results in a gradual increase in the firing rate of the inspiratory muscles rather than providing signals to them to contract instantly.

Along with the respiratory rhythm centre, the brain stem also has a chemosensitive region. It is very reactive to hydrogen ions and CO2. This centre is activated by an increase in CO2 and H+ ions, which instructs the rhythm centre to modify the breathing process and expel these substances.

There are certain receptors that, in addition to respiratory centres, have the ability to recognise changes in CO2 and H+ ion concentration and provide signals to control breathing. While some of them are receptors in the walls of bronchi and bronchioles, others are chemoreceptors found in the medulla, aortic arch, and carotid artery.

Factors Affecting the Rate of Respiration

  • Temperature: At a very high temperature, the rate of respiration decreases with time, and at a very low temperature, the respiration rate is insignificant. The optimum temperature for respiration is 20 – 30 oC.
  • Carbon dioxide: Higher concentration of carbon dioxide lower the rate of respiration. An increase in carbon dioxide concentration and the absence of oxygen adversely affect the rate of aerobic respiration.
  • Water: As the respiring organism’s water content rises, the respiratory rate does as well.
  • Light: Light regulates respiration by increasing an organism’s body temperature.

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By Team Learning Mantras