說(shuō)明呼吸生理3regulation of the respiration

1、 CO2 Transportation & Respiratory RegulationPUMC & CAMS Xue GaoCarbon Dioxide (CO2) TransportationCarbon Dioxide Dissolved in Plasma 5% Chemically Bound to Hemoglobin in RBC 7% As Bicarbonate Ion in RBC 88%CO2 diffuse from Tissue into BloodJust a little stay in plasma (5%)Most of them diffuse into r

2、ed blood cell (RBC) (95%)In Plasma (5%) NaHCO3 is main form to transportH2 CO3CO2 + H2ONa+NaHCO3CO2 + H2O H+ + HCO-3Na+NaHCO3In Red Blood Cell (RBC,95%) Chemically Bound to Hemoglobin 7% As Bicarbonate Ion form 88%Reaction of Carbonic Dioxide with Water in RBCThe Carbonic Anhydrase stimulates water

3、to combine quickly with carbon dioxideCO2 + H2OH2 CO3 H+ + HCO-3Diffuse into Plasma Cl-diffuse into RBCCarbonic AnhydraseCarbon Dioxide molecule reversibly attaches to an amine radicals of Hemoglobin to form Carbaminohemoglobin (CO2Hgb)Hgb + CO2HgbCO2Reaction of Carbonic Dioxide with Hemoglobin in R

4、BCtissuelung The ability of Hb to combine with CO2 is great than HbO2 In tissue where Hb concentration is more than HbO2 & CO2 concentration is high, so Hb is mainly in charge of CO2 transportation In lung, the process is just reverseCO2 Transport & Cl- ShiftCarbon Dioxide Dissociation Curve No Satu

5、ration Point pH and PCO2: Bohr EffectIncreased in blood CO2 & H+ has a significantly effect by enhancing the release of oxygen from Hb Binding of oxygen with Hemoglobin tends to displace carbon dioxide from Hb Increase in PO2 will diminish the affinity of hemoglobin with CO2Haldane EffectPO2=100mmHg

6、PO2=40mmHgHaldane Effect4652ml48mlCombination of oxygen with hemoglobin in the lungs cause the hemoglobin to es a stronger acidThe more highly acidic hemoglobin has, less tendency to combine with CO2 to form CO2HgbMechanism of Haldane Effect Regulation of RespirationRespiratory CenterVRGRespiratory

7、Centers Inspiratory Center (Dorsal Respiratory Group, DRG) More frequently they fire, more deeply you inhale Longer duration they fire, breath is prolonged Expiratory Center (Ventral Respiratory Group, VRG) Involved in forced expirationRespiratory Centers -MedullaRespiratory Centers -Pons Pneumotaxi

8、c Center (Upper Pons) (Pontine Respiratory Group, PRG) Limit inhale, convert inhale to exhale Sends continual inhibitory impulses to inspiratory center of the medulla oblongata Impulse frequency rises, breathe faster & shallower Apneustic Center (Lower Pons) Stimulation causes apneusisPathological B

9、reathing -Biot Breathing Chemoreceptor Reflex Pulmonary Stretch Reflex Proprioceptive Reflex Defensive ReflexReflex Regulation of RespiratoryChemoreceptor ReflexChemoreceptorsTwo forms: Peripheral Chemoreceptors Central ChemoreceptorsPeripheral ChemoreceptorCentral ChemoreceptorRostralMedullaCaudalM

10、edullaMedulla Ventral SurfaceEffective Stimulation to Chemoreceptor PCO2 H+ PO2Alveoli VentilationPCO2 CO2 will both inhibit respiration when the pressure is too low (75mmHg)Mechanism of PCO2 VACO2+H2O H2CO3H+HCO3CSFPathological Breathing -Cheyne-Stokes BreathingH+Mechanism of H+H+VACSFPO280Mechanis

11、m of PO2PO2+ Receptor: Located in the smooth muscle of bronchial airways throughout the lungs Pulmonary Inflation Reflex: When the lungs e overly inflated, the stretch receptors activate an appropriate feedback response that “switch off” the inspiratory ramp & then stop further inspiration Pulmonary

12、 Deflation Reflex Pulmonary Stretch Reflex (Hering-Breuer Reflex)Proprioceptive ReflexClinical Correlate Sleep Apnea: A disorder whereby normal breathing is periodically interrupted during sleep Obstructive Sleep Apnea: Blockage of Upper Airway Central Sleep ApneaObstructive Sleep ApneaCentral Sleep

13、 Apnea Damage to the respiratory center Abnormality of respiratory neuromuscular apparatus Less responsive to stimulatory effects of CO2 & H+Sleep ApneaHigh AltitudeAdaptation to High Altitude -Acclimatization to low PO2 Increased Pulmonary Ventilation -Role of Peripheral Chemoreceptors Increased in red blood cell & Hb concentration Increased in gas diffusing sur