CONTROL AND REGULATION OF RESPIRATORY CENTERS

1. CONTROL
OF
RESPIRATION
BY:
Mrs.Keerthi Samuel. K
Asst.Professor,
Vijay Marie CON

2. INTRODUCTION
• At rest about 200ml of oxygen
is used each minute by our
body.
• During strenuous breathing
oxygen use typically increases
15-20 fold in a normal healthy
adult.

3. RESPIRATORY CENTER
• The size of thorax is altered by action of respiratory muscles
which contract as a result of nerve impulses transmitted to
them from the centers in the brain and relax in the absence
of nerve impulses.
• RESPIRATORY CENTER: Nerve impulses are sent from
clusters of neurons located bilaterally in MEDULLA
OBLONGATA and PONS.
• THE THREE AREARS OF RESPIRATORY CENTER ARE:
 MEDULLARY RHYTHMICITY AREA
 PNEUMOTAXIC AREA
 APNEUSTIC AREA

4. 1.MEDULLARY RHYTHMICITY AREA
• FUNCTION: TO CONTROL THE RHYTHM OF RESPIRATION
• There are two areas: 1.INSPIRATORY 2. EXPIRATORY
• During quiet breathing – Inhalation lasts about 2 seconds
Exhalation lasts for 3 seconds
• Nerve impulses will be generated in inspiratory area to
establish the rhythm
• Activation of inspiratory area
• Generation of nerve impulse for 2 sec
• These impulses propagate to ext. Intercostals via
• INTERCOSTAL NERVES- EIM
• PHRENIC NERVES-DIAPHRAGM

5. The cycle repeats
Elastic recoil of lungs and thoracic wall
With no impulses ,the diaphragm and EIM reax for 3seconds
Inspiratory area becomes inactive inactive after 2sec and the nerve impulses cease
As the muscles contract INHALATION occurs.
1.MEDULLARY RHYTHMICITY AREA
Neurons of the Exp.area
remains inactive during quiet
breathing but during forceful
breathing impulses from
Insp.area activates the
Exp.area

6. 2. PNEUMOTAXIC AREA
Seen in upper pons which transmits
inhibitory impulses to inspiratory area
The major function of this area is to
turnoff the inspiratory area before lungs
become too full of air.
In other words the impulses shorten the
duration of inhalation.
When this area is active , breathing is
more rapid
FUNCTION:
CO-ORDICATES
THE
TRANSITION
BETWEEN
INHALATION
AND
EXHALATION

7. 2. APNEUSTIC AREA
Present in LOWER PONS
Stimulates and activates the
inspiratory area during
inhalation
Results in long deep
inhalation
FUNCTION:
CO-ORDICATES
THE
TRANSITION
BETWEEN
INHALATION
AND
EXHALATION

8. REGULATION
OF
RESPIRATORY
CENTER

9. CHEMORECEPTOR REGULATION OF RESPIRATORY CENTER
• The respiratory system functions to maintain proper levels
of co2 and o2 and is very responsive to the changes in
levels of these gases in the body fluids.
• The sensory neurons that responds to these chemicals are
called as CHEMORECEPTORS
• They maintain levels of co2, H+ and O2.
• This provides input to the respiratory center.
• There are two types of chemoreceptors:
• CENTRAL CHEMORECEPTORS
• PERIPHERAL CHEMORECEPTORS

10. CHEMORECPTORS CONTINUED….
CENTRAL CHEMORECEPTORS
• Located near Medulla Oblongata in CNS.
• Respond to changes in both H+,Pco2or
both in CSF
PERIPHERAL CHEMORECEPTORS
• Located in aortic bodies(clusters of
chemoreceptors in he wall of arch of
aorta) and carotid bodies(present in
carotid arteries)
• They respond to the changes in Po2,H+
and Pco2 in blood.

11. CHEMORECEPTOR REGULATION
• Normal Pco2 in blood is 40mmHg , when increased it is called HYPERCAPNIA.
• During hypercapnia
• In addition the ONLY peripheral CR respond to deficiency of O2.
Central CR are stimulated due to
increased H+
Peripheral CR are stimulated due to
increase in H+ and Pco2

12. REGULATION OF RESPIRATORY CENTER
POSITIVE FEEDBACK
When Pao2 falls from normal to 100 mmHg but
is still above 50mmhg----- PR gets stimulated
and inspiratory area in chemoreceptors gets
deactivated.
Decreased impulses to the respiratory ,muscles
of inhalation.
As breathing rate falls more and more PAo2 falls
more and more leading to fatal result.
NEGATIVE FEEDBACK
The CR participate in negative feedback regulate
levels of CO2,O2 and H+.
Due to increase in PCo2, decreased PH, decreased
Po2.
Central and peripheral chemoreceptors stimulates
inspiratory area to become active.
Rate and depth of breathing increases---
HYPERVENTILATION.
Allows inhalation of more O2 and exhalation of Co2.
Until Pao2 and H+ are lowered to normal.