1. Physiology of Respiration

2. Overview Boyle’s law Passive and active respiration
Torque, elasticity, and gravity
Volumes and capacities
Pressures
Posture and lung volume
Muscle activity during speech

3. Respiration and Boyle’s Law

4. Respiration
The exchange of gas between an organism and its environment.
Inspiration: Drawing air into the respiratory system.
Expiration: Process of evacuating air from the lungs during respiration.

5. Boyle’s Law
Boyle’s Law: Given a gas of constant temperature, as volume is increased, pressure will decrease.
Air pressure: Force exerted on walls of a chamber by molecules of air.
Natural law states that air will flow to equalize pressure.

6. When volume goes down air pressure goes up if air particle is constant
When volume goes down air pressure goes up if air particle is constant. More air means more air pressure if volume is the same. Rarefication when air particles are low.

7. Boyle’s Law Positive pressure: Produced by:
Adding air particles to a fixed volume
Or decreasing the volume of a container that has been sealed from contact with the outside
Negative pressure: Produced by:
Removing air particles from a fixed volume
Or increasing the volume of a container sealed from contact with the outside

8. Quiet vs. forced inspiration
Quiet inspiration:
Inhalation of air during periods of rest. Primarily diaphragmatic action.
Forced inspiration:
Inhalation of air during periods of physical activity (including singing & preparing to speak). Utilizes diaphragm and external intercostals, as well as accessory muscles.

9. Passive vs. Active expiration
Passive expiration:
Relaxing of muscles used for inspiration driven by torque, elasticity, and gravity
Active expiration:
Thoracic contraction forces air out of the lungs beyond that which is expired in passive expiration

10. Torque, elasticity, and gravity
Quiet vs. forced inspiration
Active vs. passive expiration

11. Torque, elasticity, and gravity
twisting of a shaft (or in this case a rib) while not permitting one end to move.
Elasticity:
The force associated with maintaining an object’s shape – a restoring force
Gravity:
Pulls abdominal viscera downward and pulls rib cage down to resting positioning.
3 forces always present acting on the diaphragm. Any time you add force that can be twisted will drive that object back to its original shape.

12. Volumes vs. Capacities Air volume: Capacity: Respiratory cycle
Quantity of air held in the lungs. Measured in liter (L), mililiters (ml), or cubic centimeters (cc).
Capacity:
Functional units. Refer to combinations of volumes that express physiological limits. Same units as volume
Respiratory cycle
One complete inspiration and expiration
Volume of space in the lungs

13. Volumes and Capacities
Normative data:
Males vs. females
Males greater volumes, and thus capacities.
Volumes peak between years and then steadily decline
VC a function of body, age, weight, and height.

14. Pressures of the Respiratory System

15. Pressure Atmospheric pressure: Intrapleural pressure:
Pressure outside the body.
Intrapleural pressure:
Pressure in the space between parietal and visceral pleurae of the thoracic cavity.
Alveolar pressure:
Pressure within alveoli.
Intraoral pressure:
Pressure within the mouth.
Subglottal pressure:
Pressure below the vocal folds.

16. Pressure-Quiet respiration
The interaction of these pressures and muscle contraction are responsible for respiration.
Contraction of diaphragm decreases intrapleural pressure
Lungs expand, dropping alveolar pressure.
Relax diaphragm, intrapleural pressure increases.
Alveolar pressure increases and air leaves lungs.

17. Pressures of the Respiratory Tissues
During inspiration muscle activity overcomes forces of torque, elasticity, and gravity.
Inspiration is an active process.
During exhalation, passive forces of torque, elasticity, and gravity are utilized.

18. Pressures of the Respiratory Tissues
The more an elastic matter is distorted, the greater the forces of restoration that drive that matter back to its resting position
The greater the amount of thoracic expansion, the more forcefully it will be driven back to resting (relaxation) volume and the more difficult it will be to hold in its expanded state

19. Relaxation Pressure Curve
Tidal Volume

20. Relaxation Pressure Curve
38% of vital capacity represents equilibrium or zero pressure.
Recoil pressures of tissues allow for expiration of ~ 55% VC.
After 55% VC, muscle of expiration are more active.

21. Pressures and Muscle Activity of Speech

22. Pressures of Speech Subglottal pressure Maintaining pressure
Minimal speech pressure 3-5 cm H2O
Conversational speech pressure: 7 cm H2O
Syllable stress
Maintaining pressure
Inhalation
Speech vs. Quiet inhalation
Exhalation
Speech vs. Quiet expiration

23. Speech pressure curve

24. Muscle Activity during Speech
Controlling speech pressure:
Checking action: Activation of the muscles of inspiration and abdominal positioning during expiration to control flow of air.
Inspiration
Diaphragm and external internal intercostals and preparatory abdominal activity
Expiration
Internal intercostals, External obliques, rectus abdominis, & latissimus dorsi

25. Review

26. Review Torque, elasticity, and gravity Volumes and capacities
volumes make up capacities
Pressures
Atmospheric
Alveolar
Intrapleural
Muscle activity during speech
Checking action

27. Respiration and the Thorax
The Rib-Lung “Battle”
The ribs are curved bones that are under substantial force to “straighten out”
Therefore, they are in a sense pulling the thorax apart, or expanding it laterally
The lungs are under significant pressure to shrink
In cadavers, the lungs often tear themselves away from the lining of the thorax, and shrink like a dried sponge
Therefore, they are, in a sense, pulling the thorax toward the midline
The lungs and ribs, then, establish a state of equilibrium, or a baseline size for the thoracic cavity from which an individual will make various manipulations

28. Respiration and the Thorax
Inspiration, or inhalation
Musculature
Diaphragm receives innervation to contract from the medulla, which is the lower brainstem
Pulls downward, which enlarges the thoracic space
Simultaneously, the intercostal muscles are stimulated
Two sets of intercostal muscles or “inter-rib” muscles
External intercostals – connect the osseous portions of the ribs across the outsider (lateral) surface
Internal intercostals – connect osseous portion of ribs to cartilaginous portion, near sternum - Two sets of internal intercostals
Interchondral portion – connects the cartilaginous portion of ribs
Interosseus portion – connects the bony portion of the ribs

29. Active/Passive Breathing

30. Respiration and the Thorax
Inspiration, or inhalation: Muscle action
Diaphragm lowers when it contracts, analogous to lowering the floor of the barrel
Intercostal muscles contract
The external intercostals raise the ribcage
The interchondral portion of the internal interchondrals twist the ribs up and out
Additional muscles, the scalenes, and sternocleidomastoid also elevate the ribcage
The cumulative action, then is one in which the ribs are elevated, and twisted outward, thereby enlarging the thoracic cavity

31. Respiration and the Thorax
Speech Breathing – Considerations regarding lung/thorax volume
A far larger inspiration is required for active breathing
The expiration phase consists of two portions
Initiallly, the passive contraction of the thorax is slowed by the muscles of inspiration
After the relaxation volume is reached, if the speaker wishes to continue, additional thoracic contraction must be carried out
The passive forces of expiration, then, provide a “background force” that diminishes as the thorax approaches, then reaches its relaxation volume
Active Expiration is continued through the contraction of muscles that raise the diaphragm, and further lower the ribcage

32. Respiration and the Thorax
Speech breathing – distinct from quiet respiration because the expiration phase takes on far greater importance, and requires far more time
Inspiration phase is often exaggerated by increased contraction of rib elevators
The release of air is regulated and slowed relative to the passive expiration of quiet breathing

33. Respiration and the Thorax
Speech Breathing: Regulating the expiration
Contraction of the muscles of inspiration slows the passive expiration
Slowing the passive expiration provides the talker the opportunity to shape the expiration into speech sounds
During quiet respiration, 40% of the respiratory cycle is inspiration, 60% expiration
During active, or speech breathing, the proportions change to favoring expiration

34. Respiration and the Thorax
Speech Breathing – Considerations regarding lung/thorax volume
Tidal Volume – the amount of air exchanged in a typical, quiet respiration cycle - About 0.5 liters
Vital Capacity – the maximum amount of air that can be exchanged in a person’s respiration cycle - About 5 liters
Total lung capacity includes about another 2 liters (the residual volume) that is typically not expelled
Therefore tidal volume is about 10% of the vital capacity
The amount of air in the lungs when the V. folds are open and the pressure is equal with the atmosphere is the relaxation volume

35. Respiration and the Thorax

36. Respiration and the Thorax
Speech Breathing – Considerations regarding lung/thorax volume
A far larger inspiration is required for active breathing
The expiration phase consists of two portions
Initiallly, the passive contraction of the thorax is slowed by the muscles of inspiration
After the relaxation volume is reached, if the speaker wishes to continue, additional thoracic contraction must be carried out
The passive forces of expiration, then, provide a “background force” that diminishes as the thorax approaches, then reaches its relaxation volume
Active Expiration is continued through the contraction of muscles that raise the diaphragm, and further lower the ribcage

37. Respiration and the Thorax
Speech Breathing – Expiration phase
Contraction of abdominal muscles
Pushes abdominal viscera toward the backbone
Squeezes the fluids/tissues upward (can’t go inferiorly (pelvis), or posteriorly (vertebral column)
Elevates the diaphragm (raises the floor of the thorax)
Contraction of the interosseous portion of the internal interchondrals
Pulls the ribs closer together and down
Overall action of speech expiration is to produce a gradual release of sub-glottal air pressure
The rate at which the pressure is expelled is held constant through the muscle control outlined above

38. Respiration and the Thorax
Speech Breathing – Expiration phase
Correlation between the power of speech and the rate of expiration
Intense speech requires a more powerful expelling of air
Therefore the air is used up more quickly, and loud speech cannot be sustained as long as normal speech
The pressure level is sustained, as in normal speech, but at a higher level

39. Respiration and the Thorax
Differences between loud and normal speech
About 25% of the vital capacity is used for normal speech
Loud speech requires far more subglottal pressure, therefore more air to sustain the speech – estimates place the amount at about 40% of the vital capacity
Additional strain is then placed on the valving mechanism (the vocal folds) when loud speech is generated

40. Respiration and the Thorax

41. Respiration and the Thorax
Voice disorders
May be due to problems with respiration in cases where insufficient subglottal air pressure is generated
May also result from difficulty coordinating the muscles of respiration
Such difficulty would reduce the effectiveness of the power source for speech
For example, talker may not raise the ribcage in synchrony with the lowering of the diaphragm