Dorsal respiratory group
Encyclopedia
The dorsal respiratory group (DRG) is located in the dorsomedial region of the medulla
, and is composed of cells in the solitary tract nucleus. The DRG is one of two known respiratory neuron localizations, with the other being the ventral respiratory group
. The DRG is found in many types of fish
and mammal
s.
. It is stimulated via the apneustic center
in the lower pons
and is also a part of the solitary tract, which is responsible for appropriating responses to sensory information from chemoreceptors and mechanoreceptors in humans.
Inspiration begins when cells of the solitary tract nucleus (along with cells of the ventral respiratory group
) begin a steady increase in firing, leading to contraction of the respiratory muscles. When neurons in the DRG fire, impulses travel down the phrenic
and intercostal nerves to stimulate the diaphragm and external intercostal muscle
s. The thoracic cavity
expands and air rushes into the lungs due to the negative pressure, producing inspiration. When the cells stop firing, the inspiratory muscles relax, inspiration ceases, and exhalation
begins.
The rhythm of the DRG produces a respiratory rate of 12-16 breaths per minute in humans. Inspiration usually lasts approximately 2 seconds, and expiration lasts about 3 seconds. The normal inspiration rate and rhythm is called eupnea
, and difficult respiration is termed dyspnea
.
Medulla oblongata
The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...
, and is composed of cells in the solitary tract nucleus. The DRG is one of two known respiratory neuron localizations, with the other being the ventral respiratory group
Ventral respiratory group
The ventral respiratory group is a column of neurons located in the ventrolateral region of the medulla, extending from the caudal facial nucleus to -400μm obex...
. The DRG is found in many types of fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
and mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s.
Respiratory effects
The DRG is involved in the generation of respiratory rhythm, and is primarily responsible for the generation of inspirationInhalation
Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....
. It is stimulated via the apneustic center
Apneustic center
The apneustic center of the lower pons appears to promote inspiration by stimulation of the I neurons in the medulla oblongata providing a constant stimulus....
in the lower pons
Pons
The pons is a structure located on the brain stem, named after the Latin word for "bridge" or the 16th-century Italian anatomist and surgeon Costanzo Varolio . It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it...
and is also a part of the solitary tract, which is responsible for appropriating responses to sensory information from chemoreceptors and mechanoreceptors in humans.
Inspiration begins when cells of the solitary tract nucleus (along with cells of the ventral respiratory group
Ventral respiratory group
The ventral respiratory group is a column of neurons located in the ventrolateral region of the medulla, extending from the caudal facial nucleus to -400μm obex...
) begin a steady increase in firing, leading to contraction of the respiratory muscles. When neurons in the DRG fire, impulses travel down the phrenic
Phrenic nerve
The phrenic nerve originates mainly from the 4th cervical nerve, but also receives contributions from the 5th and 3rd cervical nerves in humans....
and intercostal nerves to stimulate the diaphragm and external intercostal muscle
Intercostal muscle
Intercostal muscles are several groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing...
s. The thoracic cavity
Thoracic cavity
The thoracic cavity is the chamber of the human body that is protected by the thoracic wall ....
expands and air rushes into the lungs due to the negative pressure, producing inspiration. When the cells stop firing, the inspiratory muscles relax, inspiration ceases, and exhalation
Exhalation
Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....
begins.
The rhythm of the DRG produces a respiratory rate of 12-16 breaths per minute in humans. Inspiration usually lasts approximately 2 seconds, and expiration lasts about 3 seconds. The normal inspiration rate and rhythm is called eupnea
Eupnea
In the human respiratory system, eupnea or eupnoea is normal, good, unlabored ventilation, sometimes known as quiet breathing or resting respiration...
, and difficult respiration is termed dyspnea
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
.