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Topic 3c: Respiration

Topic 3c: Respiration. Learning Objectives. Posses a knowledge of respiratory anatomy sufficient to understand basic respiratory physiology and its relation to speech sound generation. Describe how physical laws help explain how air is moved in and out of the body

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Topic 3c: Respiration

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  1. Topic 3c: Respiration

  2. Learning Objectives • Posses a knowledge of respiratory anatomy sufficient to understand basic respiratory physiology and its relation to speech sound generation. • Describe how physical laws help explain how air is moved in and out of the body • Outline the functional subdivisions of the lung volume space • Compare and contrast characteristics of speech breathing and metabolic/vegetative breathing • Use the pressure-relaxation curve to explain the active and passive forces involved in controlling the respiratory system • Describe how various respiratory impairments can lead to diminished speech production abilities

  3. Learning Objectives • Posses a knowledge of respiratory anatomy sufficient to understand basic respiratory physiology and its relation to speech sound generation.

  4. Speech Breathing • Why do we breathe? • How does breathing help us speak?

  5. Life and Speech Breathing ARE DISTINCT PROCESSES in terms of • Primary functional goal • Surface features • Mechanisms underlying action

  6. Role of breathing in speech • Respiratory System is a Variable Power Source • Aerodynamic power needed to generate sound sources • Phonation, frication, bursts, aspiration • Must be able to vary power to allow for • Intensity variation (phonation & obstruent production) • Fundamental frequency variation • Must also meet metabolic needs of speaker

  7. Structure and Mechanics of Respiratory System • Pulmonary system • Lungs and airways • Upper respiratory system • Lower respiratory system • Chest wall system • “Houses” pulmonary system • Structures on which muscle activity is generated • Pulmonary system & chest wall are linked (pleural linkage)

  8. Pulmonary system: lower respiratory tract

  9. Pulmonary system: lower respiratory tract

  10. Chest wall system • Rib cage • Abdomen • Diaphragm

  11. Chest wall-Lung relation • Lungs not physically attached to the thoracic walls • Lungs: visceral pleura • Thoracic wall: parietal pleura • Filled with Pleural fluid • Ppleural < Patm - “pleural linkage” allows the lungs to move with the thoracic wall • Breaking pleural linkage Ppleural = Patm - pneumothorax

  12. Thorax

  13. Abdomen

  14. Diaphragm

  15. Learning Objectives • Describe how physical laws help explain how air is moved in and out of the body

  16. Key Quantities Pressure (P) Volume (V) Flow (U) Boyle’s Law V=k/P or V P=k As V↑ P↓ As V↓P↑ Physics of Breathing

  17. B A Flow (U)

  18.  Vthoracic = Palv Palv < Patm (- Palv) P differential = density differential  air molecules flowing into lungs = inspiration  Vthoracic = Palv Palv > Patmos(+ Palv) P differential = density differential  air molecules flow out of lungs = expiration Moving air within respiratory system Patm: atmospheric pressure Palv: alveolar pressure* Vthoracic : thoracic volume P = k/V: Boyle’s Law *pressure in lungs typically described as alveolar pressure

  19. Requires Muscular forces Elastic forces Strategies ∆ Length ∆ Circumference Changing thoracic volume (Vthoracic): two degree of freedom model

  20. Changing length of thoracic cavity Diaphragm Abdominal wall muscles

  21. Changing circumference of thoracic cavity Rib cage elevation (e.g. external intercostals m.) Rib cage lowering (e.g. internal intercostals m.)

  22. Summary: Changing lung volume ( Vlung) • pleural linkage:Vthoracic = Vlung •  Vthoracic is • raising/lowering the ribs (circumference) • Raising:  Vthoracic = inspiration • Lowering:  Vthoracic =expiration • Raising/lowering the diaphragm (vertical dimension) • Raising: Vthoracic =expiration • Lowering: Vthoracic =inspiration

  23. Learning Objectives • Outline the functional subdivisions of the lung volume space

  24. Measuring Lung Volume: Spirometry Lung Volume

  25. Measuring Lung Volume: Spirometry Lung Volume Time

  26. Selected volumes, capacities and levels Tidal Volume (TV) • Volume of air inspired/expired during rest breathing. Expiratory Reserve Volume (ERV) • Volume of air that can be forcefully exhaled, “below” tidal volume. Inspiratory Reserve Volume (IRV) • Volume of air that can be inhaled, “above” tidal volume. Vital Capacity (VC) • Volume of air that can be inhaled/exhaled (i.e. VC=IRV +TV+ERV) Residual Volume (RV) • Volume of air left after maximal expiration. Measurable, but not easily so. Total Lung Capacity (TLC) • Volume of air enclosed in the respiratory system (i.e. TLC=RV+ERV+TV+IRV) Resting End Expiratory Level (REL) • Location in lung volume space where tidal breathing typically ends (35-40 % VC in upright position)

  27. NOTE • Some authors use the term FRC (functional residual capacity) instead of REL (resting end-expiratory level) • Behrman uses resting lung volume (RLV) • Refers to equivalent “place” in the lung volume space

  28. Typical Volumes & Capacities Vital Capacity (VC) 4-5 liters Total Lung Capacity (TLC) ~ one liter more than VC Resting Tidal Volume (TV) ~ 10 % VC Resting expiratory end level (REL) ~ 35-40% VC when upright Typical Rest Breathing Values Respiratory rate 12-15 breaths/minute Alveolar Pressure Palv +/- 2 cm H20 Airflow ~ 200 ml/sec Some typical adult values

  29. Learning Objectives • Compare and contrast characteristics of speech breathing and metabolic/vegetative breathing

  30. Rest Breathing Volume 10 % VC at rest Alveolar Pressure Palv +/- 2 cm H20 Average Airflow 100-200 ml/sec Ratio of inhalation to exhalation ~40/60 to 50/50 Speech Breathing Volume 20-25 % VC @ normal loudness (note this varies by utterance length) 40 % loud speech Alveolar Pressure Palv + 8-10 cm H20 on expiration Average Airflow 100-200 ml/sec Ratio of inhalation to exhalation ~ 10/90 Speech vs. Life Breathing

  31. Respiratory System Mechanics • It is spring-like (elastic) • Elastic systems have an equilibrium point (rest position) • What happens when you displace it from equilibrium?

  32. Learning Objectives • Use the pressure-relaxation curve to explain the active and passive forces involved in controlling the respiratory system

  33. Displacement away from equilibrium Restoring force back to equilibrium Longer than equilibrium equilibrium

  34. Displacement away from equilibrium Restoring force back to equilibrium Shorter than equilibrium equilibrium

  35. Displacement away from equilibrium Restoring force back to equilibrium Shorter than equilibrium Longer than equilibrium equilibrium

  36. Displacement away from REL Restoring force back to REL Lung Volume Below REL Lung Volume Above REL REL

  37. Is the respiratory system heavily or lightly damped?

  38. Respiratory Mechanics: Bellow’s Analogy • Bellows volume = lung volume • Handles = respiratory muscles • Spring = elasticity of the respiratory system

  39. No pushing or pulling on the handles ~ no exp. or insp. muscle activity Volume in bellows at rest ~ REL Patmos = Palv, therefore no airflow REL: Respiratory System Equilibrium

  40. Shifting Lung Volume away from REL muscle force elastic force • pull handles outward from rest • V increases ~ Palv decreases • Inward air flow • INSPIRATION muscle force

  41. Shifting Lung Volume away from REL muscle force elastic force • push handles inward from rest • V decreases ~ Palv increases • outward air flow • EXPIRATION muscle force

  42. Respiratory Mechanics: Bellow’s Analogy Forces acting on the bellows/lungs are due to • Elastic properties of the system • Passive • Always present • Muscle activity • Active • Under nervous system control (automatic or voluntary) • Moving to a volume other than REL requires an external force • Muscle activity (inspiratory or expiratory) • Mechanical assistance (mechanical ventilator)

  43. Characteristics of System Elasticity • Since elastic recoil forces will have the effect of exerting a pressure within the respiratory system, the effect is termed the relaxation pressure • Magnitude of relaxation pressure is roughly proportionate to the amount of displacement from REL • REL is expressed as a lung volume • This gives rise to a relaxation pressure curve • Plots relaxation pressure (units Palv) as a function of lung volume

  44. Relaxation Pressure Curve (as in Behrman)

  45. Relaxation Pressure Curve(Our version)

  46. 60 40 relaxation pressure 20 REL Alveolar Pressure (cm H20) 0 -20 -40 -60 80 60 40 20 0 100 % Vital Capacity

  47. Breathing for Life: Inspiration • pulling handles outward with net inspiratory muscle activity

  48. Breathing for Life: Expiration • No muscle activity • Recoil forces alone returns volume to REL

  49. 60 40 20 relaxation pressure Alveolar Pressure (cm H20) 0 -20 -40 -60 80 60 40 20 0 100 % Vital Capacity Breathing for Life ~ 2 cm 10 %

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