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Chapter 5

Chapter 5. RESPIRATION. Introduction  Containing: inspiration & expiration  Functions: O btain O 2 from external environment R emove CO 2 form the body  Respiratory processes: P ulmonary ventilation G as exchange in the lung G as transport in the blood

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Chapter 5

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  1. Chapter 5 RESPIRATION Introduction  Containing:inspiration & expiration Functions: Obtain O2 from external environment Remove CO2 form the body Respiratory processes: Pulmonary ventilation Gas exchange in the lung Gas transport in the blood Gas exchange in the tissue

  2. Respiratory processes

  3. § 1. Pulmonary ventilation Definition Principles of pulmonary ventilation *Driving force Direct~:pressure changes in alveoli Source ~: contraction of respiratory muscles Inspiratory muscles: Diaphragm, External intercostal muscle Expiratory muscles: Diaphragm, Ext- & Internal intercostals Accessoryrespiratory muscles

  4. Respiratory movement

  5. Typesof respiration Eupnea&Forcedbreathing (Deepbreathing) Abdominal&Thoracicbreathing Principlesof pulmonary ventilation Contraction (Relaxation)of inspiratory musclesExpansion(Reduction) of thoracic cavity(?)Distension(Recoil)of alveoli Intrapulmonary pressure()<(>) atmo- sphericpressureAir flows into(out of) the alveoli

  6. Intrapulmonary pressure Inspiratoryphase: <1 atm Expiratory phase:>1 atm At the end of inspiration or expiration:=1 atm Intrapleural pressure Concept&Changes during respiratory cycle More negative as inspiratory processing Less negative as expiratory processing Measurement&Expression Direct & Indirect measurement 775 mmHg or 5 mmHg Always < 1 atm under static condition

  7. Changes of intrapulmonary & intrapleural pressure during respiratory cycle

  8. Formation IAP & PRF has opposite directions, so IPP=IAPPRF At the end of insp- & expiration, so IPP=ASPPRF If ASP=0, IPP=0PRF= PRF IPP: intrapleural pressure IAP: intra alveolar pressure PRF: pulmonary recoil force ASP: atmospheric pressure

  9. Formation of intrapleural negative pressure

  10. Significance Physiological ~ Distend the lung & Make inspiration easier Promote venous & lymph return in the chest Pathological ~ (Pneumothorax) Collapse the lung & Make inspiration difficult Affect venous & lymph return Fatal in pulmonary & circulatory failure cases Importance Keep the interpleural cavity hermetically sealed

  11. *Resistance to breathing Elastic ~ of the lung Elastic ~ & Compliance CL=1/RL=VL/PL(L/cmH2O) Static compliance (Cst) of the lung Sshaped curve, divided into 3 portions Flattened upper portion Steep middle portion Flattened lower portion Special compliance (Csp) Csp = CL/TLC

  12. Static compliance (Cst) of the lung

  13. S shaped compliance curve of the lung

  14. Source of elastic ~ of the lung Elastic tissue(1/3) &Alveolar surface tension(2/3) Pulmonary surfactant Nature:Alipoprotein,Main lip component is DPL Characteristics:Bothhydro-philia & -phobicity Source:Type II alveolar epithelial cells Distribution:Innersurface of the alveoli Action:Reducethe alveolar surface tension Significance:Decrease the inspiratory resistance, Stabilizethe volume & pressure in the alveoli, Preventpulmonary edema

  15. Pulmonary compliance curve when filled with air or saline

  16. Pulmonary recoil force in the big & small alveoli communicated each other

  17. Elastic ~ of the thorax Characteristics of elastic resistance of the thorax

  18. Non-elastic resistance Airway resistance (main) Definition & Calculation Factors affecting the airway resistance: Velocity of air flow: RAW VAF Type of air flow:Laminar flow & Turbulence Diameter of airway:Transmural pressure; Radiate traction by pulmonary parenchyma; Autonomic nervous system; Chemical factors

  19. Differences between the large & small airway

  20. Pulmonary volume & capacity *Tidal volume (TV) *Inspiratory reserve volume (IRV) *TExpiratory reserve volume (ERV) *Residual volume (RV) *Inspiratory capacity (IC) *Functional residual capacity (FRC) *Vital capacity (VC) *Forced vital capacity (FVC) & Forced expiratory capacity (FEC) *Total lung capacity (TLC)

  21. Pulmonary volume & capacity

  22. Forced expiratory volume

  23. Pulmonary ventilation volume *Minute ventilation volume *Maximal (voluntary) ventilation & Percentage of ventilation reserve volume *Anatomical, Alveolar & Physiological dead space, Alveolar ventilation MVV=TV ×RF; AV=(TVDSV)×RF MVV=TV/2×2RF;AV=(TV/2DSV)×2RF MVV=2TV×RF/2;AV=(2TVDSV)×RF/2

  24. § 2. Respiratory gas exchange Mechanisms of gas exchange *Driving force: Partial pressure of O2 or CO2 *Mode: Diffusion of gas *Condition: Permeability of membrane Processes of gas exchange Po2 & Pco2in alveoli, blood & tissue(mmHg)

  25. Processes of gas exchange

  26. Factors affecting gas exchange * Diffusion rate of gas *Ventilation/perfusion ratio (V/Q) Definition & its normal value (0.84) IfV/Q  > 0.84: Alveolar dead space  V/Q  < 0.84: Functional A-V shunt Anoxia occurs more easily than CO2 retention Affecting by gravity when a person stands

  27. Respiratory membrane

  28. Ventilation/perfusion ratio (V/Q)

  29. DN: § 3. Gas transport in the blood Oxygen transport *Forms of transport Physically diffusion & Combination with Hb *Characteristics of Hb combined with O2 Fast, reversible, need not enzyme, oxygenate with Fe2+, O2 combined with Hb is 4:1, S shaped oxygendissociation curve *Oxygen capacity, content & saturation *Cyanosis & carbon monoxide poisoning

  30. *Oxygen dissociation curve Definition & why it is in S shaped Physiological advantages of S shaped curve The flattened upper portion (60~100 mmHg) The steep middle portion (40~60 mmHg) The steep lower portion (15~40 mmHg) Factors affecting oxygen dissociation curve Concept of P50, affinity to O2, right or left shift Factors:pH & Pco2(Bohr effect), temperature, 2, 3-DPG, others (Fe2+Fe3+, CO)

  31. Oxygendissociation curve

  32. Factors affecting oxygen dissociation curve

  33. Carbon dioxide transport *Forms of transport Physically diffusion Combination with Hb HCO3 & HHbNHCOOH *Carbon dioxide dissociation curve *Influence of combination of Hb with O2 on CO2 transport (Haldane effect)

  34. Carbon dioxide transport in the blood

  35. Carbon dioxide dissociation curve

  36. § 4. Regulation of respiratory activity Respiratory centers *In the spinal cord *In the lower brain stem Research techniques: Brain stem transection, Microelectrode, etc. Medullary oblongata: DRG:VL-NTS VRG:cVRG, i(or r)VRG, Böt C, pre-Böt C Pons:Pneumotaxiccenter, PBKF (NPBM+KF) *In the higher brain: Cerebral cortex, Limbic system, Hypothalamus

  37. Research on respiratory centers: Brain stem transection

  38. Formation of respiratory rhythm *A key region of its generation: Pre-Böt C *Central inspiratory activity generator (CIAG) & Inspiratory off switchmechanism (IOS) Respiratory reflexes *Pulmonary stretch reflex (Hering-Breuer ~) Inflation & deflation reflex *Chemoreflex Peripheral & central chemoreceptors Respiratory regulation of CO2, H+& O2 Interaction of CO2, H+ & O2 on the regulation *Proprioceptive reflex of respiratory muscles

  39. PBKF + + + CIAG, Insp. Neurons IOS − + + Insp. Muscular Neurons + + Insp. movement PSR

  40. Off switch mechanism + − − Insp. center (medulla) Insp. Neurons (spinal cord) Ⅹ Ⅹ Contraction (or relaxation) of insp. muscles Inflation (or Deflation) Inflation receptor or deflation receptor

  41. Paco2 [H+]a Pao2 Resp. A  & F  Carotid & aortic bodies Resp. Center (Medulla) (−) O2 O2 HCO3 H+ CO2 CO2+H2O Central chemoreceptor H+ H+ Blood CSF A: amplitude; F: frequency BBB: blood-brain barrier CSF: cerebrospinal fluid BBB

  42. Respiratory regulation of CO2, H+ & O2

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