Hyperventilation Respiration Muscles of respiration control of respiration central and peripheral chemoreceptors effect of exercise on respiration Effect of respiration on heart rate

1. To record the effect of voluntary
hyperventilation on breath holding
& the recovery of normal breathing
rhythm
Dr. Irtaza Rehman
Author of the book “The Extraordinary Life”

3. Learning Objectives
• To Understand the mechanics of breathing
• To understand the Central & Peripheral control
of breathing
• To know the effect of exercise & heart rate on
respiration
• To study the effects of hyperventilation

4. Q. What is hyperventilation?
• A. DEEP breathing
• B. FAST/Rapid breathing
• Ans. BOTH

5. • Lungs are not attached to the thoracic walls.
• Except at the hilum from mediastinum.

6. Lungs are suspended in
their own pleural cavity
Glued to the thoracic
walls
Well lubricated
Can slide freely as chest
expands/contracts

7. The suction process
Excess pleural fluid
suctions into
lymphatic channels
Pleural pressure  Suction pressure
 Negative pressure

8. Pleural Pressure
• At the start of inspiration = -5 cm of H20
• -5 cm of H20  To hold the lungs open to their
resting level
• During Inspiration = -7.5 cm of H20 (Inc V, Dec P)
• Result: Inhalation of 0.5 L of air

9. Alveolar pressure
• Pressure inside lungs alveoli
• Equal to atmospheric pressure = 0 cm of H20
• -1  0.5 L inhalation
• +1  0.5 L exhalation

10. MECHANICS OF BREATHING
• 1. Diaphragm is the most important muscle for
inspiration.
• When the diaphragm contracts, the abdominal contents
are pushed downward, and the ribs are lifted upward and
outward, increasing the volume of the thoracic cavity.
A. Muscles of inspiration

11. MECHANICS OF BREATHING
• 2. External intercostals and accessory muscles: not used for
inspiration during normal quiet breathing.
• are used during exercise and in respiratory distress.
• Most important Muscles to raise the rib cage: 3S
1. SCM 2. Serratus interior 3. Scaleni (first 2 ribs)
A. Muscles of inspiration

12. MECHANICS OF BREATHING
• A. Muscles of expiration
1. Rectus Abdominis
2. Internal intercostals

13. Central control of breathing
• 1. Medulla oblongata
• A. Dorsal respiratory group: Responsible for inspiration
and generates the basic rhythm for breathing.
• Input: IX and X
• X: From chemo and mechanoreceptors in lungs
• IX: From chemoreceptors
• Output: Phrenic Nerve to diaphragm
Respiratory center:

14. Central control of breathing
• b. Ventral respiratory group: Expiration
• is not active during normal, quiet breathing, when
expiration is passive.
• is activated, for example, during exercise, when
expiration becomes an active process

15. Central control of breathing
• 2. Pneumotaxic center: upper pons
• Inhibits inspiration
• regulates respiratory rate and depth of breathing

17. • Cerebral cortex: voluntary control; therefore, a person
can voluntarily hyperventilate or hypoventilate.
• Hypoventilation (breath-holding) is limited by the
resulting increase in PCO2 and decrease in PO2
Central control of breathing

18. Chemical control of Breathing
• Central chemoreceptor: Medulla
• Breathing rate increased by:
*Decreased pH *Increased PCO2

19. Q. What is the direct stimulus for
chemo sensitive area?
• A. CO2
• B. H+ ions
•Ans. H+

20. But H+
cannot
easily
pass
through
BBB

21. Q. What is the most potent
stimulus for chemo sensitive area?
• A. H+ ions
• B. CO2
• Ans. CO2

22. Effect of PC02 on ventilation

23. • Peripheral chemoreceptors:
Carotid and aortic bodies
• Breathing rate increased by:
* Decreased PO2 (<60 mm Hg) * Increased PCO2
*Decreased pH
Chemical control of Breathing

24. Q. Which receptors are more
powerful?
• Ans. Central Chemoreceptors
• Ans. Peripheral chemoreceptors
Q. Which receptors give
more rapid response?

25. Effect of P02
• Oxygen has no direct effect on central
respiratory center
• Only indirect effect through peripheral
chemoreceptors

26. Respiratory response during Exercise
• O2 Consumption: Increased
• CO2 Production: Increased
• Ventilation rate: Increased
• Arterial PO2 & PCO2: No change

27. • Arterial pH: moderate exercise : No change
• Arterial pH: Strenuous exercise : Decrease (due to L.A)
• Venous PCO2: Increased
• Pulmonary blood flow (cardiac output) : Increased
Respiratory response during Exercise

28. Effect of respiration on Heart rate
• Inspiration: Increased H.R (Due to increase
venous return)
• Expiration: Decreased H.R

29. Hyperventilation
• When you inhale much deeper and take much
faster breathing than normal.
• Increased intensity of rate and depth of
breathing.
• Causes CO2 wash out

30. Breathing patterns on spirometer

31. Breath holding after hyperventilation

32. Recovery after breath holding

33. Hyperventilation
“Like most kids growing up, my
friends and I would do breath-
holding contests in my
neighbor’s pool. The technique
we all used to extend our time
was to hyperventilate right
before we went underwater”
~James Nestor

34. “Most people think that the
reason hyperventilation
allows you to hold your
breath longer is that you’re
saturating your blood with
fresh oxygen. The more
oxygen in your blood, the
longer you can hold your
breath”
Hyperventilation

35. When you hyperventilate, you
reduce the amount of CO2 in your
blood, but you don’t boost its
oxygen. These lower levels of CO2
delay the activation of the body’s
“need to breathe” reflex far past the
point where it should have been
triggered. In short, the reason you
can hold your breath longer when
you hyperventilate isn’t because of
an increase in oxygen, but because
of a decrease in CO2.
Hyperventilation

37. Jazakumullahu Khair ♥
(May ALLAH swt reward you with goodness)