logging in or signing up Physiology of Respiration drdeepac2007 Download Post to : URL : Related Presentations : Let's Connect Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 1594 Category: Education License: Some Rights Reserved Like it (2) Dislike it (0) Added: August 04, 2011 This Presentation is Public Favorites: 7 Presentation Description A short and concise presentation on the physiology of respiration Comments Posting comment... By: damaziotembo (12 month(s) ago) its straight forward. Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 2: PHYSIOLOGY OF VENTILATION & OXYGENATION Dr Deepa C MDSlide 3: VENTILATION Mechanical process that moves air in and out of the lungs EXTERNAL RESPIRATION Gas exchange between air in lungs and blood Transport of O₂ and CO₂ in the blood INTERNAL RESPIRATION Gas exchange between the blood and tissues O₂ utilisation & CO ₂ production RESPIRATIONSlide 4: RESPIRATORY SYSTEM Ventilating pump - Respiratory control centres in the brain - Connecting tracts and nerves - Chest wall and respiratory muscles Gas-exchange system - LungsSlide 5: RESPIRATORY TRACT UPPER Nose, pharynx & assoc. structures LOWER Larynx, tracheobronchial treeSlide 6: CONDUCTING ZONE Trachea, bronchi , bronchioles & terminal bronchioles 16 generations RESPIRATORY ZONE Respiratory bronchioles, alveolar ducts and alveoli Rest 7 generations TRACHEOBRONCHIAL TREESlide 7: TOTAL CROSS-SECTIONAL AREA Trachea – 2.5 cm² Alveoli – 11,800 cm²Slide 8: 300 MILLION ALVEOLI Total area of alveolar walls in contact with capillaries in both lungs – 70 m²Slide 9: ALVEOLOCAPILLARY MEMBRANE Pulmonary epithelium Capillary endothelium Fused basement membranes PAMs, APUD cells, plasma cellsSlide 10: ALVEOLOCAPILLARY MEMBRANESlide 11: ALVEOLAR SURFACE TENSION & SURFACTANT Dipalmitoylphosphatidylcholine Type II pneumocytes Increases lung compliance Reduces lung’s tendency to recoil Makes work of breathing easier Prevents alveolar collapse Prevents pulmonary edemaSlide 12: MECHANICS OF VENTILATIONSlide 14: Pump handle motion increases the AP dimension of rib cage Bucket handle motion increases lateral dimension of rib cageSlide 15: Intrapleural -10 cm H₂O Intrapleural -2.5 cm H₂OSlide 17: END OF EXPIRATION DURING INSPIRATIONSlide 18: END OF INSPIRATION DURING EXPIRATIONSlide 19: LUNG VOLUMES & CAPACITIESSlide 20: TIDAL VOLUME (TV) – the volume of gas inspired or expired in an unforced respiratory cycle (approximately 500 ml) INSPIRATORY RESERVE VOLUME (IRV) – the max. vol. of air that can be inspired during forced breathing in addn. to TV (2100–3200 ml) EXPIRATORY RESERVE VOLUME (ERV) – the max. vol. of air that can be exspired during forced breathing in addn. to TV (1000–1200 ml) RESIDUAL VOLUME (RV) – the vol. of air remaining in the lungs after maximal forced expiration (1200 ml) LUNG VOLUMESSlide 21: LUNG CAPACITIES INSPIRATORY CAPACITY (IC) – the max. amount of air that can be inspired after a tidal expiration (IRV + TV) FUNCTIONAL RESIDUAL CAPACITY (FRC) – amount of air remaining in the lungs after a tidal expiration (RV + ERV) VITAL CAPACITY (VC) – the max. amount of air that can be expired after a max. inspiration(TV + IRV + ERV) TOTAL LUNG CAPACITY (TLC) – the total amount of air in the lungs after a max. inspirationSlide 22: CLOSING VOLUME The lung volume above residual volume at which airways in the lower, dependent parts begin to close off CLOSING CAPACITY = CV + RV Old age and infants – CC > FRCSlide 23: AIRWAY RESISTANCE : 0.6 – 2.4 cm H₂O/L/sec Inversely proportional to R⁴ TOTAL COMPLIANCE = ∆V/∆P 150ml/cm H₂O (STATIC) 100ml/cm H₂O (DYNAMIC) ↓compliance ↑ work of breathing WORK OF BREATHING - work performed by the respiratory muscles in stretching the elastic tissues of the chest wall and lungs (elastic work – 65%), moving inelastic tissues(7%) and moving air through the respiratory passages(28%) 0.3 -0.8 kg-m/minSlide 24: PRESSURE-VOLUME & DISTRIBUTION OF VENTILATION The pressure volume curve varies between apex and base of the lung. At the base the lungs are slightly compressed by the diaphragm so upon inspiration have greater scope to expand. The volume change is greater for a given change in pressure. Dependent alveoli are more compliant than the non-dependent ones. Hence alveolar ventilation declines with height from base to apex.Slide 26: High High High VENTILATION & PERFUSION Zone I P A > Ppa Zone II Ppa >P A > Ppv Zone III Ppa > Ppv >P ASlide 28: ZONESSlide 29: DEAD SPACE & SHUNT DEAD SPACE – wasted ventilation ( no gas exchange due to absent perfusion) eg.; pulmonary embolism SHUNT – wasted perfusion (eg.; atelectatic segment, one-lung ventilation) Alveolar Ventilation = (V T - V D ) x RR V D /V T = (PaCO₂ – P E CO₂) / PaCO₂ Q S /Q T = (CćO₂ – CaO₂) / (CćO₂ – CvO₂)Slide 30: Ventilation in the alveoli is matched to perfusion through pulmonary capillaries. If ventilation decreases in a group of alveoli, P CO 2 increases and P O 2 decreases. Blood flowing past these alveoli does not get oxygenated. Decreased tissue P O 2 around under-ventilated alveoli constricts their arteries (mediated by O₂-sensitive K⁺ channels) and diverts blood to better ventilated alveoli LOCAL CONTROL OF VENTILATION & PERFUSIONSlide 31: ADJUSTMENTS IN VENTILATION AND PERFUSIONSlide 32: GAS EXCHANGE LUNGS TISSUESSlide 33: GAS LAWS CHARLES’ LAW - The volume occupied by a gas is directly related to the absolute temperature ( V α T ) HENRY’S LAW - The amount of gas dissolved in a liquid is determined by the pressure of the gas and it’s solubility in the liquid. DALTON’S LAW - The total pressure of a gas mixture is the sum of the pressures of the individual gases. BOYLE’S LAW - The pressure exerted by a gas is inversely proportional to its volume ( P α 1/V )Slide 34: ALVEOLAR GAS EQUATION P A O₂ = [F I O₂ (P B - P H₂O )] - [PaCO₂/R]Slide 35: DIFFUSION ACROSS THE ALVEOLOCAPILLARY MEMBRANE The diffusing capacity of the lung for a given gas is directly proportional to the surface area of the alveolocapillary membrane inversely proportional to its thickness The diffusing capacity for CO (DLCO) is measured as an index of diffusing capacity At rest -- 25ml/min/mmHg DLO₂ - 25ml/min/mmHgSlide 37: OXYGEN TRANSPORT Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%) Oxygen content = [ 1.34 x Hb x SpO₂] + [0.003 x PO₂] Arterial blood – 19.8 ml O₂/dL Venous blood – 15.2 ml O₂/dLSlide 38: OXYGEN-Hb DISSOCIATION CURVE AT pH 7.40 & TEMPERATURE 38⁰CSlide 39: FACTORS AFFECTING Hb AFFINITY FOR OXYGEN pH [Bohr effect] Temperature pCO₂ 2,3-DPGSlide 40: P₅₀ is the PO₂ at which Hb is 50% saturated with O₂ Normal P₅₀ is 25 mm Hg The higher the P₅₀ , the lower the affinity of Hb for O₂ SHIFT OF O₂- Hb DISSOCIATION CURVE TO RIGHT ↓ affinity for O ₂…..↑ O ₂ release ↓pH ↑Temperature ↑ PCO ₂ ↑ 2,3 - DPGSlide 41: HbF – SHIFT OF CURVE TO LEFTSlide 43: TRANSPORT OF CARBONDIOXIDE Carbon dioxide is transported as bicarbonate ions (70%) in combination with blood proteins (23%) and in solution with plasma (7%) [solubility 20 times more] CO₂ content Arterial blood – 49 ml/dL Venous blood – 53 ml/dLSlide 44: CHLORIDE SHIFT Mediated by Band 3 proteinSlide 45: Insert fig. 16.39 REVERSE CHLORIDE SHIFT IN LUNGS HALDANE EFFECT – binding of O₂ to Hb reduces the affinity of Hb for CO₂Slide 46: TRANSPORT OF O₂ AND CO₂Slide 48: O₂ consumption = Cardiac output x C(a-v) O₂ = 250 ml/min CO₂ production = 200 ml/min RESPIRATORY QUOTIENT = V CO₂ /V O₂ = 0.8 . .Slide 49: Neural Chemical Non-chemical REGULATION OF RESPIRATION NEURAL CONTROL VOLUNTARY CONTROL -- Cerebral cortex CS tracts Resp. motor neurons AUTOMATIC CONTROL -- Medullary pacemaker cells in the pre-Botzinger complexSlide 50: INSPIRATORY AREA (DORSAL RESP. GROUP) determines basic rhythm of breathing causes contraction of diaphragm and external intercostals EXPIRATORY AREA (VENTRAL RESP. GROUP) Inactive during normal quiet breathing Activated by inspiratory area during forceful breathing Causes contraction of internal intercostals and abdominal musclesSlide 51: Switching between inhalation and exhalation controlled by: PNEUMOTAXIC CENTER located in pons inhibits inspiratory area of medulla to stop inhalation APNEUSTIC AREA located in pons stimulates inspiratory area of medulla to prolong inhalationSlide 54: CENTRAL CHEMORECEPTOR When Pa CO 2 increases carbon dioxide crosses the BBB, but not H + Central chemoreceptors monitor the P CO 2 indirectly in the CSF. The bicarbonate and H+ are formed and the receptors respond to the H + Feedback via the respiratory control centre increases ventilation in response to increased Pa CO 2 Decreased Pa CO 2 slows ventilation rate.Slide 55: PERIPHERAL CHEMORECEPTORS Carotid and aortic bodies Detect changes in arterial PO 2 and [H+] Cause reflex stimulation of ventilation following significant fall in arterial PO 2 or a rise in [H+] Respond to arterial PO 2 not oxygen content Increased [H+] usually accompanies a rise in arterial PCO 2 CO 2 + H 2 O H 2 CO 3 H 2 CO 3 - + H + Transduction mechanismSlide 57: NON-CHEMICAL CONTROL Afferents from proprioceptors Afferents from pons, hypothalamus and limbic system Afferents from baroreceptors: arterial, atrial, ventricular, pulmonary Vagal afferents from the receptors in the airways and lungsSlide 58: Rhythm of ventilation is also modified by: TEMPERATURE temp = ventilation (and vice versa) sudden cold stimulus may cause apnea PAIN Sudden severe pain can cause apnea Prolonged somatic pain increases respiratory rate Visceral pain may slow respiratory rate IRRITATION OF AIRWAYSSlide 59: RECEPTORS IN LUNG AND AIRWAY VAGAL - myelinated and unmyelinated (C ) fibers MYELINATED Slowly adapting & rapidly adapting SLOWLY ADAPTING RECEPTORS (among airway sm. m) Stimulus – Lung inflation Response – Hering-Breuer inflation and deflation reflexes, bronchodilation, tachycardia RAPIDLY ADAPTING RECEPTORS (among airway ep. cells) Stimulus – Lung hyperinflation, exogenous & endogenous substances Response – Hyperpnea, cough, bronchoconstriction, mucus secretionSlide 60: UNMYELINATED C FIBERS -- J RECEPTORS Located close to pulmonary blood vessels Stimulus – Lung hyperinflation, exogenous & endogenous substances Response – Apnea folld. by rapid breathing, bronchoconstriction, bradycardia, hypotension, mucus secretion (PULMONARY CHEMOREFLEX) Occurs in pathological states such as pulmonary congestion or embolizationSlide 63: THANK YOU You do not have the permission to view this presentation. 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