The document discusses the neural control of breathing. The main components that control automatic respiration are located in the medulla. The medullary respiratory center contains the pre-Botzinger complex, which acts as the pacemaker for respiration, regulating rate and rhythm. It also contains the dorsal respiratory group that controls inspiration and the ventral respiratory group that controls expiration. The pontine respiratory center modulates breathing and contains the pneumotaxic center, which limits inspiration, and the apneustic center, which prolongs inspiration. Together these centers located in the medulla and pons generate the rhythmic breathing pattern.

1. Neural Control of Breathing
or
Neural Control of Respiration
Dr Pramod kumar
MBBS, MD

2. Neural Control Of Breathing
Main components of automatic respiration are located in Medulla.
Spontaneous rhythmic discharge of medullary neuron is modified by
neurons in Pons.
Medullary Respiratory Center:-
1. Pre-Botzinger Complex (Pre-Botc)
2. Dorsal Respiratory Group (DRG) /
(Inspiratory Center)
1. Ventral Respiratory Group (VRG)
Pontine Respiratory Center:-
1. Pneumotaxic center
2. Apneustic Center
--- Pre-Botc

3. Medullary Respiratory Center
1. Pre-Botzinger Complex
 Pacemaker cells of respiration. (Rate & Rhythm of respiration)
 Responsible for generation of respiratory rhytm and regulate rate of
respiration.
 It generate rhythmic impulse even in in-vitro brain slices.
2. Dorsal Respiratory group (DRG)/ Inspiratory center
 Mainly concerned with inspiration .
 Neurons innervating the primary muscles of inspiration i.e, Diaphragm &
external intercosatal muscles.
3. Ventral Respiratory Group (VRG)
 Mainly concerned with Forceful expiration.
 Remain totally inactive during normal quite respiration but act when high
level of ventilation are required esp during heavy exercise.(They especially
provide powerful expiratory signal to abdominal muscle).

4. Pontine Respiratory center
1. Pneumotaxic center
 Primary function is to limit inspiration (i.e controlling Depth of inspiration)
and secondarily increase rate of breathing. l/t Shallow and Rapid breathing.
 It also inhibits apneustic center ,further inhibiting inspiration.
 Its damage cause deep & slower respiration (in intact vagus) ,and prolonged
inspiratory spasm (apneusis) resembling breath holding (when vagus are
also cut.)
2. Apneustic center
 It excites inspiratory center (DRG) and produce prolonged inspiratory drive
which delays the onset of expiration.
 Named so, because it is primarily responsible for apneusis (Prolonged
inspiratory gasp).
 Two influences seems to keep the apneustic center in check:- (i) Pneumotaxic
center of upper pons & (ii) Stretch receptors in lung via Vagus.

5. Medullary Respiratory Center
1. Pre-Botzinger Complex  Pacemaker cells of respiration. (Rate & Rhythm of respiration)
 Responsible for generation of respiratory rhytm and regulate rate of respiration.
 It generate rhythmic impulse even in in-vitro brain slices.
2. Dorsal Respiratory group
(DRG)/ Inspiratory center
 Mainly concerned with inspiration .
 Neurons innervating the primary muscles of inspiration i.e, Diaphragm & external
intercosatal muscles.
3. Ventral Respiratory Group
(VRG)
 Mainly concerned with Forceful expiration.
 Remain totally inactive during normal quite respiration but act when high level of
ventilation are required esp during heavy exercise.(They especially provide
powerful expiratory signal to abdominal muscle).
Pontine Respiratory center
1. Pneumotaxic center  Primary function is to limit inspiration (i.e controlling Depth of inspiration) and
secondarily increase rate of breathing. l/t Shallow and Rapid breathing.
 It also inhibits apneustic center ,further inhibiting inspiration.
 Its damage cause deep & slower respiration (in intact vagus) ,and prolonged
inspiratory spasm (apneusis) resembling breath holding (when vagus are also cut.)
2. Apneustic center  It excites inspiratory center (DRG) and produce prolonged inspiratory drive which
delays the onset of expiration.
 Named so, because it is primarily responsible for apneusis (Prolonged inspiratory
gasp).
 Two influences seems to keep the apneustic center in check:- (i) Pneumotaxic
center of upper pons & (ii) Stretch receptors in lung via Vagus.

6. Medullary Respiratory Center
1. Pre-Botzinger Complex  Pacemaker cells of respiration. (Rate & Rhythm of
respiration)
 Responsible for generation of respiratory rhytm.
2. Dorsal Respiratory group
(DRG)/ Inspiratory center
 Mainly concerned with inspiration .
3. Ventral Respiratory Group
(VRG)
 Mainly concerned with Forceful expiration.
Pontine Respiratory center
1. Pneumotaxic center  Primary function is to limit inspiration (i.e
controlling Depth of inspiration)
2. Apneustic center  It excites inspiratory center (DRG) and produce
prolonged inspiratory drive (Deep inspiration)
INDIA
IN- Inspiratory center
DRG- Dorsal respiratory Group → Normal inspiration
A- Apneustic center →Deep inspiration

7. Transection effect
 Main components of automatic respiration are located in Medulla.
 After transection of brain stem at inferior border of pons
spontaneous respiration continues but somewhat irregular &
gasping.
Lesion of pneumotaxic center (transection at mid pons) cause deep &
slower respiration (in intact vagus) ,and prolonged inspiratory spasm
(apneusis) resembling breath holding (when vagus are also cut.)