RESPIRATORY FUNCTIONS MECHANICS OF RESPIRATORY SYSTEM GAS TRANSPORT RESPIRATORY SYSTEM STOMATOLOGY Author of presentation: doc. MUDr. Milena Šimurdová, CSc. STEPS IN THE DELIVERY OF O2 TO THE CELLS airways alveoli alveolar-capillary m. capillary UTILIZATION OF O2 BY MITOCHONDRIA TRANSPORT OF O2 IN THE BLOOD DIFFUSION OF O2 ACROSS ALVEOLAR-CAPILLARY MEMBRANE DIFFUSION OF O2 FROM CAPILLARY TO THE CELLS 1 VENTILATION OF THE LUNGS INTERNAL RESPIRATION CO2 OUTPUT ~250 ml / min O2 UPTAKE ~300 ml / min AT REST AIR PASSAGES ANATOMICAL DEAD SPACE –CONDUCTING ZONE NASAL PASSAGES PHARYNX LARYNX TRACHEA BRONCHI BRONCHIOLES TERMINAL BRONCHIOLES 2 RESPIRATORY ZONE (GAS EXCHANGE) Total alveolar area ~100 m2 Other physiological functions: air is warmed, cleaned and takes up water vapour respiratory reflex responses to the irritants speech and singing (function of larynx) Folie7 před cut CAST OF HUMAN AIR PASSAGES TRACHEA BRONCHI BRONCHIOLES TERMINAL BRONCHIOLES 3 AERODYNAMIC RESISTENCE Folie8 předb cut aa ciliated cylindrical epithelium lamina propria visceral pleura smooth muscle cells cartilage blood vessels gland goblet cell mucus 4 AUTONOMIC INNERVATION of smooth muscle cells Muscarinic receptors: Acetylcholine activates bronchoconstriction b-adrenergic receptors: Noradrenaline activates bronchodilatation BRONCHUS Æ < 1 mm TERMINAL BRONCHIOLE f = 12/min VT = VA + VD VD part of tidal volume remaining in the dead space ~ 150 ml 5 4.2 l/min 6 l/min ALVEOLAR VENTILATION VA · = VA x f 1.8 l/min DEAD SPACE VENTILATION VD · = VD x f PULMONARY MINUTE VENTILATION V ∙ = VT x f VT tidal volume ~ 500 ml VA part of tidal volume entering alveoli ~ 350 ml 6 IN HEALTHY INDIVIDUALS both spaces are practically identical DEAD SPACE TOTAL GAS VOLUME NOT EQUILIBRATED WITH BLOOD (without exchange of gasses) ANATOMICAL dead space - volume of air passages FUNCTIONAL (total) dead space ANATOMICAL dead space + total VOLUME of ALVEOLI without functional capillary bed I AIR PASSAGES II MEASURABLE PARAMETERS LUNG VOLUMES FUNCTIONAL INVESTIGATION CHARACTERISTIC PRESSURES · · · · DEAD SPACE IV COMPOSITION OF ALVEOLAR AIR V ALVEOLAR-CAPILLARY MEMBRANE RESPIRATORY MUSCLES LUNGS ELASTICITY COMPLIANCE WORK OF BREATHING III ACTIVE AND PASSIVE FORCES · · · · VI TRANSPORT OF GASSES (O2 and CO2) Folie10 před cut SPIROMETRY water seal subject inspiration expiration inverted bell 7 (measurements of lung volumes, capacities, functional investigations, …) Folie11 před cut bb LUNG VOLUMES TIDAL VOLUME VT EXPIRATORY RESERVE VOLUME ERV ~1.7 8 maximal inspiratory level RESIDUAL VOLUME RV ~1.3 maximal expiratory level end of quiet expiration DILUTION METHOD He INSPIRATORY RESERVE VOLUME IRV ~2.5 [l ] end of quiet inspiration He reservoir (Vr) RV ci 3 Calculation of residual volume RV from the initial and final He concentrations in reservoir (ci , cf). He reservoir (V) RV cf Þ Equilibration of the air in the residual volume and reservoir Principle of method: 1 Maximal expiration, 2 Repeated inspiration from and expiration into a reservoir (known volume Vr) with inert gas He (known concentration ci) Folie11 před cut bb maximal expiratory level maximal inspiratory level VC - the largest amount of air that can be expired after maximal inspiration VC VITAL CAPACITY = VT + IRV + ERV ~ 4.7 l VC 9 TLC TOTAL LUNG CAPACITY = VC + RV ~ 6.0 l TLC ~1.2 l RV FUNCTIONAL RESIDUAL CAPACITY <3.0 l end of quiet expiration INSPIRATORY CAPACITY >3.0 l I AIR PASSAGES II MEASURABLE PARAMETERS LUNG VOLUMES FUNCTIONAL INVESTIGATION CHARACTERISTIC PRESSURES · · · · DEAD SPACE IV COMPOSITION OF ALVEOLAR AIR V ALVEOLAR-CAPILLARY MEMBRANE RESPIRATORY MUSCLES LUNGS ELASTICITY COMPLIANCE WORK OF BREATHING III ACTIVE AND PASSIVE FORCES · · · · VI TRANSPORT OF GASSES (O2 and CO2) FUNCTIONAL INVESTIGATION OF THE LUNGS TIMED VITAL CAPACITY (FEV1 - forced expiratory volume per 1 s) PULMONARY MINUTE VENTILATION RMV (respiratory minute volume) at rest (0.5 l x 12 breathes/min = 6 l/min) PEAK EXPIRATORY FLOW RATE (PEFR) (~10 l/s) MAXIMAL VOLUNTARY VENTILATION (MVV) (125-170 l/min) 10 0 1 3 2 4 5 6 7 8 9 time (s) 1 2 3 4 5 6 FEV1 VC ≥ FEV1 VC 80 % I AIR PASSAGES II MEASURABLE PARAMETERS LUNG VOLUMES FUNCTIONAL INVESTIGATION CHARACTERISTIC PRESSURES · · · · DEAD SPACE IV COMPOSITION OF ALVEOLAR AIR V ALVEOLAR-CAPILLARY MEMBRANE RESPIRATORY MUSCLES LUNGS ELASTICITY COMPLIANCE WORK OF BREATHING III ACTIVE AND PASSIVE FORCES · · · · VI TRANSPORT OF GASSES (O2 and CO2) Graf změny intrapleur tlaku Graf změny objemu Graf změny plícního tlaku Obrzměny intrapleur tlaku Silbernagl pulmonalis parietalis PLEURA FORCES PARTICIPATING IN RESPIRATION 12 QUIET RESPIRATION EXPIRATION - only passive (elastic) forces are in action INSPIRATION - active forces of inspiratory muscles prevail PASSIVE FORCES represented by: ACTIVE FORCES performed by respiratory muscles lungs elasticity chest elasticity obr 2a cut RESPIRATORY MUSCLES accessory muscles external intercostals diaphragm internal intercostals abdominal muscles EXPIRATORY INSPIRATORY 13 INSPIRATORY muscles QUIET breathing diaphragm (> 80 % ) external intercostals (< 20 % ) EXPIRATORY muscles 14 internal intercostals muscles of the anterior abdominal wall (abdominal recti, …) Only at FORCED breathing accessory inspiratory muscles (mm. scalene) FORCED breathing in addition dýchábí žebra Silbernagl dychani Hrudní košSilbernagl Bucket-handle and water-pump handle effects 16 P pressure r radius T surface tension LAW OF LAPLACE spherical structures EXPANSION OF ALVEOLI P1 > P2 P1 P2 COLLAPSE OF ALVEOLI - ATELECTASIS P r T r T P 2 = ? PATHOLOGY 17a SURFACTANT SURFACE TENSION LOWERING AGENT obr 5 přech ALVEOLAR EPITHELIAL CELLS macrofage fatty acids, choline, glycerol, amino acids, etc.) surfactant surfactant cycle exocytosis of lamellar bodies PHOSPHOLIPID dipalmitoyl fosfatidyl cholin TYPE II specialized granular epithelial cells PRODUCTION OF SURFACTANT TYPE I thin epithelial cells DIFFUSION OF GASSES EFFECT MAINLY IN THE EXPIRED POSITION O2 20.98 % FO2 @ 0.21 N2 78.06 % FN2 @ 0.78 CO2 0.04 % FCO2 = 0.0004 Other constituents BAROMETRIC (ATMOSPHERIC) PRESSURE AT SEA LEVEL 1 atmosphere = 760 mm Hg PARTIAL PRESSURES OF GASSES IN DRY AIR AT SEA LEVEL PO2 = 760 x 0.21 = ~160 mm Hg PN2 = 760 x 0.78 = ~593 mm Hg PCO2 = 760 x 0.0004 = ~0.3 mm Hg 20 1 kPa = 7.5 mm Hg (torr) COMPOSITION OF DRY ATMOSPHERIC AIR obr 12 přech cut COMPOSITION OF ALVEOLAR AIR 760 mm Hg INSPIRED AIR EXPIRED AIR dead space O2 100.0 CO2 39.0 H2O 47.0 right heart left heart veins arteries periphery capillaries 21 760 mm Hg partial pressures in mm Hg 760 mm Hg N2 O2 158.8 CO2 0.3 N2 601.0 … O2 115.0 CO2 33.0 H2O 47.0 N2 564.0 … O2 95.0 CO2 41.0 H2O 47.0 N2 … … O2 40.0 CO2 45.0 H2O 47.0 N2 … … O2 40.0 CO2 45.0 H2O 47.0 N2 … … physiological shunts O2 100.0 CO2 39.0 ? ? I AIR PASSAGES II MEASURABLE PARAMETERS LUNG VOLUMES FUNCTIONAL INVESTIGATION CHARACTERISTIC PRESSURES · · · · DEAD SPACE IV COMPOSITION OF ALVEOLAR AIR V ALVEOLAR-CAPILLARY MEMBRANE RESPIRATORY MUSCLES LUNGS ELASTICITY COMPLIANCE WORK OF BREATHING III ACTIVE AND PASSIVE FORCES · · · · VI TRANSPORT OF GASSES (O2 and CO2) obr 13 přech cut nucleus RED BLOOD CELL O2 O2 O2 Hb HbO2 CO2 CO2 CO2 ~1 µm 23 ALVEOLAR-CAPILLARY (RESPIRATORY) MEMBRANE ALVEOLAR-CAPILLARY (RESPIRATORY) MEMBRANE interstitial space ALVEOLAR AIR PO2 = 100 PCO2 = 39 (mm Hg) alveolar epithelial cell time interval of erythrocyte contact with respiratory membrane at rest 0.75 s PULMONARY CAPILLARY diameter about 5 µm nucleus capillary endothelial cell DIFFUSION OF GASES obr 16 přech cut PO2 PCO2 PO2 100 PCO2 40 mm Hg venous blood PO2 40 PCO2 46 mm Hg 40 100 60 80 mm Hg 24 time 0.75 s time interval of contact of erythrocyte with respiratory membrane at rest Δ PO2 @ 60 mm Hg Δ PCO2 @ 6 mm Hg equalization with alveolar pressures PO2 100 PCO2 40 mm Hg TIME COURSE OF CAPILLARY PO2 AND PCO2 DURING GRADUAL EQUILIBRATION WITH ALVEOLAR AIR I AIR PASSAGES II MEASURABLE PARAMETERS LUNG VOLUMES FUNCTIONAL INVESTIGATION CHARACTERISTIC PRESSURES · · · · DEAD SPACE IV COMPOSITION OF ALVEOLAR AIR V ALVEOLAR-CAPILLARY MEMBRANE RESPIRATORY MUSCLES LUNGS ELASTICITY COMPLIANCE WORK OF BREATHING III ACTIVE AND PASSIVE FORCES · · · · VI TRANSPORT OF GASSES (O2 and CO2) obr 17 přech b cut obr 17 přech a cut HAEMOGLOBIN α α β β 1 nm Fe Fe N N N N N N N N DEOXY OXY N N N polypeptide chain polypeptide chain O2 Fe3+ (methaemoglobin) oxidation 25 fetal Hb γ γ Fe2+ tetramer porfyrin Hb4 + 4 O2 ↔ Hb4O8 oxygenation O2–HAEMOGLOBIN DISSOCIATION CURVE 100 50 PO2 (mm Hg) CO Hb 26 myoglobin fetal Hb 50 0 50 100 0 plateau area steep portion ↓ pH, ↑ CO2 ↑ BPG (2,3-bisphosphoglycerate) ↑ temperature methaemoglobin BOHR´S EFFECT (¯ pH, CO2) physiological range v a P50 physically dissolved O2 (1.4%) PCO (mm Hg) obr 19 přech cut TRANSPORT OF CO2 Cl- HAMBURGER CHLORIDE SHIFT H2 CO3 CO2 + H2O CA CA – carbonic anhydrase H2O 27 HCO3- H+ + H+ + deoxyHb- H-deoxyHb HCO3- Cl- CO2 obr 20 přech b cut obr 20 přech a cut HbO2 CO2 O2 28 CO2 CO2 CO2 physically dissolved (~5.3%) CO2 O2 Cl- HCO3- CO2+ H2O HCO3- + H+ CO2 + H 2O HCO3- + H+ (~89%) Hb.CO2 CO2 + Hb-NH2 Hb.NH-COO- (carbamino-Hb) (~5.3 %) 60% in plasma, 29% in red blood cell obr 21 přech copy HALDANE EFFECT CO2 DISSOCIATION CURVE deoxygenated blood 5 10 15 20 25 30 10 20 30 40 50 60 70 PCO2 (mm Hg) physically dissolved CO2 a v oxygenated blood 29 deoxygenated blood in peripheral tissues oxygenated blood in the lungs CO2 + H2O H2CO3 H+ + HCO3- Hb- + H+ HHb TISSUES: DEOXY-Hb binds H+ more readily (weaker acid) Þ ↑ amount of chemically bound CO2 ? physiological values in arterial and venous blood Hb.NH.COO- 1 Hb- + H+ HHb 2 LUNGS: H+ is released from OXY-Hb Þ ↓ amount of chemically bound CO2 DEOXY-Hb END Folie17 přech a cut 3 Folie17 přech a cut 1 Folie17 přech a cut 2 VT [l] time -3 -6 [mm Hg] [mm Hg] +1 -1 11 P.V = const PA ALVEOLAR (INTRAPULMONARY, LUNG) PA PPL INTRAPLEURAL (INTRATHORACIC) PPL TIME COURSE OF PRESSURES AT QUIET RESPIRATION INSPIRATION EXPIRATION PA < PATM PA > PATM measured curve theoretical curve ? ? 1 kPa = 7.5 mm Hg LUNGS ELASTICITY INHERENT TISSUE ELASTICITY (elastin and collagen fibres) SURFACE TENSION FORCES air-liquid interface in alveoli 15 obr 3 přech 200 150 100 50 0 0.4 ALVEOLAR PRESSURE (kPa) 0.8 1.2 1.6 2.0 HYSTERESIS LOOP INFLATION DEFLATION opening pressure AIR LUNGS ELASTICITY SALINE 200 150 100 50 0 0.4 ALVEOLAR PRESSURE (kPa) 0.8 1.2 1.6 2.0 HYSTERESIS LOOP INFLATION DEFLATION opening pressure AIR SALINE Factors involved in HYSTERESIS LOOP 17b LAPLACE LAW (responsible for high opening pressure of alveoli) Dynamic changes in the DENSITY of surfactant molecules during INSPIRATION and EXPIRATION obr 6 přech b cut COMPLIANCE (VOLUME STRETCHABILITY) alveolar pressure DPA (mm Hg) 0 100 50 150 200 -50 -100 0 +1 -1 +2 +3 -2 VC RV FRC relaxation volume 18 relaxation pressure curve STATIC MEASUREMENT IN CLOSED SYSTEM V P DP DV compliance is increased ¯ stiffness of the tissue compliance is decreased stiffness of the tissue P V C D D = end of quiet expiration Valsalva maneuver Müller´s maneuver TOTAL RESPIRATORY SYSTEM (lungs and chest) ELASTIC (STATIC) WORK to overcome the elastic forces of the chest and lungs DYNAMIC WORK to overcome the resistance of air passages during the air movement – AERODYNAMIC RESISTANCE (~ 28%) to overcome the friction during mutual movement of inelastic tissues – VISCOUS RESISTANCE (~ 7%) 19 TOTAL WORK OF RESPIRATORY MUSCLES AT QUIET BREATHING (65%) (35%)