The document discusses regulation of respiration, including: 1. The respiratory center is located in the medulla oblongata and consists of inspiratory and expiratory neurons that generate rhythmic breathing patterns. 2. Breathing is also regulated by centers in the pons and hypothalamus as well as reflexes from lung stretch receptors, irritant receptors, and J-receptors in the lungs. 3. The tone and rhythm of breathing is controlled by chemoreceptors sensitive to oxygen, carbon dioxide, hydrogen ions and the autonomic nervous system through the vagus nerves.

1. 1. Regulation of respiration
a) respiratory center, its localization
b) tone of the respiratory center
c) reflex self-control of respiration, mechanisms of
change of respiratory phases
Regulation of Respiration

2. Regulation of Respiration
Regulation of respiration is realized by reflex and
humoral mechanisms.
The localization of the respiratory center was studied
in 1812 Legalua, Flurens , Mislavsky in 1885.
They used methods of transsection and irritation and
proved that the respiratory center is in the medulla
oblongata.

4. Respiratory Center (RC) is a complex
of nerve structures (a constellation of
nerve centers) located in the various parts
of the CNS.
Main working Center is a bulbar center.

5. Medulla oblongata (automatical center) - inspiratory
and expiratory neurons, which are located in the dorsal
and ventral nuclei.
Functions of dorsal respiratory group’s neurones:
generate inspiratory action potentials in steadily
increasing ramplike fashion, and responsible for the
basic rhytm of respiration.
Functions of ventral respiratory group’s neurones:
generate inspiratory and expiratory action potentials.
1. Medulla oblongata

6. The nature of the rhythmic activity of respiratory neurons
Respiratory neurons with different patterns of rhythmic
activity were found in the medulla oblongata:
a) Full
b) Early
c) Late
d) Inspiratory-expiratory
e) Expiratory-inspiratory
f) Continuous
1. Medulla oblongata

7. Only in some of the inspiratory and expiratory neurons, the
onset of the discharge and the duration of the pulse train
strictly coincide with the period of the corresponding phase
of the respiratory cycle,
However, with all the variety of types of excitation of different
respiratory neurons of the medulla oblongata in each of
them, the nature of the rhythmic activity remains, as a rule,
constant.
1. Medulla oblongata

8. a) "Full" inspiratory and expiratory neurons, the rhythmic excitation of which exactly
coincides in time with the corresponding phase of respiration;
b) "Early" inspiratory and expiratory neurons, giving a short series of impulses
before the start of inhalation or exhalation;
c) "Late", showing salvo activity after the start of inspiration or expiration:
d) "Inspiratory-expiratory", which begin to be excited in the inspiratory phase and
remain active at the beginning of expiration;
e) "Expiratory-inspiratory", the activity of which begins during inhalation and
captures the beginning of exhalation;
f) "Continuous", working without pauses, but with an increase in the frequency of
impulses during inhalation or exhalation.
1. Medulla oblongata

9. 2. Pons. Pneumotaxic and Apneustic centers.
Pneumotaxic Center participates in the switching phases of the
respiratory cycle (switch-off inspiratory ramp signal). Thus limits period of
inspiration.
During «turn off the pneumotaxic center» breathing slows.
Apneustic Center - it regulates metabolism and tone in the bulbar center.
3. Hypothalamic area also takes part in the regulation of respiration.
4. Cerebral cortex - adaptation respiration to changing environmental
conditions.
5. Spinal cord – motor-neurons (centers) of respiratory muscles.

10. Spinal centers
- cervical region - the nucleus of the phrenic nerve.
- thoracic region - the nuclei of the intercostal muscles.

11. The respiratory center is
connected with the
intercostal muscles by the
intercostal nerves, and
with the diaphragm by the
phrenic ones.
The bronchial tree (bronchi
and bronchioles) is
innervated by the vagus
nerve.
Rhythmically repetitive
nerve impulses directed to
the diaphragm and
intercostal muscles
provide ventilation
movements.

12. The tone of the respiratory center is
maintaned by reflex and humoral ways
RC receives afferent impulses from the
mechanoreceptors of lungs and airways of the
respiratory muscles.
Humoral regulators of RC are chemoreceptors
• central (bulbar);
• peripheral.

13. Central (bulbar) chemoreceptors are sensitive to:
1. The concentration of H+ - ions.
2. CO2 tension in the extracellular fluid of the
brain.
Peripheral chemoreceptors are located in the blood
vessels walls and are sensitive to:
1. Decreased of O2 tension (hypoxemia).
2. Increased of CO2 tension (hypercapnia).
3. Increased concentration of H + ions (acidosis)
4. Decreased of CO2 tension (hypocapnia).

14. Role of CO2 in the regulation of respiration
was showed in Frederick’s experiment in 1890
tracheal clamping in dog A causes dyspnea in dog B;
dyspnea in dog B causes slow breathing in dog A

15. Impulses from chemoreceptors along the sinus nerve go to the
dorsal nucleus, exciting inspiratory neurons
hypoxemia hypercapnia hypercapnia
RC RC
Cortex Cortex
B
A

16. Reflex self-regulation of respiration
The RC receives afferent impulses from
mechanoreceptors of the lungs, airways and
respiratory muscles.

17. 17
Types of lung receptors
• Lung stretch receptors (mechanoreceptors or
proprioceptors)
• Irritant receptors
• J-receptors
Reflex self-regulation of respiration

18. 18
Lung stretch receptors
The expansion of the lungs during inhalation stimulates the stretch
receptors (proprioceptors) located in the bronchial tree and they send
more and more impulses through the vagus nerve to the expiratory
center.
This temporarily suppresses the inspiratory center and inhalation.
The external intercostal muscles now relax, the stretched lung tissue
contracts elastically - exhalation occurs.
After exhalation, the stretch receptors in the bronchial tree are no
longer stimulated. Therefore, the expiratory center is turned off and
inhalation can begin.
AP frequency in the afferent fibers of the vagus nerve increases
during inspiration and decreases during expiration
Reflex self-regulation of respiration

19. The mechanism of rhythmic alternation
of inhalation and exhalation associated with
interchange excitation of inspiratory and
expiratory neurons on the principle of
negative feedback.
Reflex self-regulation of respiration

20. Role of the vagi
◼ The rhythm (rate),and depth
of respiration are controlled
by reflexes from the lugs
through the vagi.
◼ When both the vagi are cut,
respiration becomes slow
and deep.
Reflex self-regulation of respiration

21. Hering and Breuer have cut all the tissues of a dog in the
neck area, saving the spinal cord and n.Vagus.
When they made double-sided pneumothorax, dog’s
chest made inspiration.
When they inflated the lungs, dog’s chest made
exspiration.
After cutting the vagus nerve, the reflex disappeared,
breathing became slow and deep.
Reflex self-regulation of respiration

22. The increase in lung volume is caused
three reflex effect:
◼ 1. The inspiratory-inhibitory reflex.
◼ 2. The expiratory-facilitating reflex.
◼ 3. The paradoxical effect of Hed.
(Hering-Breuer reflexes)

23. bilateral transection of the vagus nerve leads
breathing to become rare

24. 24
Irritant receptors respond to corrosive gases, tobacco smoke, dust, and
cold air.
They are located between the epithelial cells of the airways. The reflex
response is bronchoconstriction and hyperpnea.
These receptors are "rapidly adapting", since they are characterized by
rapid adaptation and, apparently, they not only respond to agents harmful
to the walls of the respiratory tract, but also play a certain role in
mechanoreception.
It is possible that the excitation of irritant receptors by histamine released
during attacks of bronchial asthma, to some extent, determines the
bronchospasm characteristic of this condition.
Irritant receptors

25. 25
J-receptors ("juxtacapillary" receptors) are so named because
they are loated in the alveolar walls near the capillaries.
This arrangement is supported by their very quick reaction to the
injection of chemicals into the pulmonary vessels.
Impulses from these receptors go along the slow unmyelinated
fibers of the vagus nerves, leading to the establishment of
frequent shallow breathing, although with severe irritation, it may
stop completely.
There is evidence that J-receptors can respond to the overflow of
blood in the pulmonary capillaries and an increase in the volume
of interstitial fluid in the walls of the alveoli.
Perhaps they play a role in the onset of dyspnea (i.e., a feeling
shortness of breath), that occurs with left ventricular failure and
interstitial pulmonary edema.
J-receptors

26. LEVELS OF ORGANIZATION
OF THE RESPIRATORY CENTER
КОРКОВЫЙ ОТДЕЛ
ДЫХАТЕЛЬНОГО
ЦЕНТРА
ЛИМБИЧЕСКИЙ ОТДЕЛ
ДЫХАТЕЛЬНОГО ЦЕНТРА
ГИПОТАЛАМИЧЕСКИЙ
ОТДЕЛ ДЫХАТЕЛЬНОГО
ЦЕНТРА
ПНЕВМОТАКСИЧЕСКИЙ
ЦЕНТР ВАРОЛИЕВА МОСТА
ДЫХАТЕЛЬНЫЙ ЦЕНТР
ПРОДОЛГОВАТОГО МОЗГА
СПИНАЛЬНЫЕ МОТОНЕЙРОНЫ
МЕЖРЕБЕРНЫХ МЫШЦ
Apneustic Center
Cortical
respiratory center
Limbic section of
respiratory center
Hypothalamic section of
respiratory center
Pons
pneumotaxic center
Medullar
respiratory center
Spinal neurons
of intercostal muscles

27. Regulation of respiration provides:
1. Maintaining arterial blood gases and brain
extracellular fluid.
2. Adaptation of respiration to changed
conditions of the environment and life
activity of the organism.