Respiration is involuntary process and is regulated by Nervous system and Some Chemicals in blood.
The voluntary regulation is done by higher Centres in cerebrum while involuntary regulation is of two types: Nervous regulation and chemical regulation.
* Nervous regulation: The process of regulation is regulated by nerve
Centres in medulla oblongata and pons varolli.
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In medulla oblongata the dorsal respiratory group (DRG) and ventral
respiratory group (VRG) are present.
* Dorsal respiratory group (DRG): It is located in the dorsal portion
of medulla oblongata. It regulates the general rhythm of respiration and is
also called inspiratory or rhythm Centre. It discharges information or stimulus
for 2 seconds and this information passes into diaphragm and EICM. The
Contraction of these Cause inspiration. Then it get paused for 3 seconds and
during that expiration takes place. It is responsible for quite /normal
respiration. This DRG is mainly responsible for inspiration.
* Ventral respiratory group: It is located antero-lateral to dorsal respiratory group in medulla oblongata. During normal respiration, this remains inactive and even does not play any role in the basic respiratory rhythm. Earlier, the Ventral group neurons were Collectively Called expiratory Centre. However, It has both inspiratory and expiratory neurons. Under enhanced respiration, it sends information to both inspiratory and expiratory muscles.
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In pons, pontine Centers are present
Which are
Apneustic Center and pneumotaxic Center.
* pneumotaxic Center: is present in upper Pons. It acts as switch off
Center for respiration. It Sends information to DRG to inhibit the signals. It
increases rate of respiration by decreasing time of inspiration.
* Apneustic Center: is present in lower pons. It increases depth of
inspiration by acting directly on DRG. It inhibits the functioning of
pneumotaxic Center.
* when both pneumotaxic and apneustic center sends information to DRG at the same time, DRG obeys pneumotaxic Center.
* Chemical regulation: The chemoreceptors present in body sends information
to respiratory Centers to regulate rate of respiration. Two types of
chemoreceptors are present: Central Chemoreceptors and peripheral
Chemoreceptors.
* Central Chemoreceptors: Are present in medulla oblongata adjacent
to DRG. It detects PCO2 and PH and sends
information to DRG. If PCO2 increases and PH decreases, the rate of respiration
Increases. It does not response to P02.
to Central receptor and increases rate of respiration
* Peripheral Chemoreceptors: Are of two types:
Aortic Chemoreceptors and Carotid
Chemoreceptors.
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Aortic Chemoreceptors or bodies: are two or more in number and
are located near the arc of aorta.
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Carotid Chemoreceptors or bodies: are located on either Side near the
bifurcation of common Carotid artery.
The peripheral Chemoreceptors respond to increased PC02, increased H+ concentration and lowered PO2 in
arterial blood and Sends information.
* Mechanical regulation or Herring- Breurer reflex: The stretch
receptors present in Wall of alveolie, bronchioles and bronchus detect pressure
of air and when air pressure is high
they get stretched and sends information to respiratory Center to inhibit
respiration.