SlideShare une entreprise Scribd logo
1  sur  21
Télécharger pour lire hors ligne
3/18/2013




          Respiratory Physiology


                                                 Lecture 2


        Andreas W. Henkel, Ph.D.




     Diagnosis of lung malfunction


Respiration             Exhale
volume        Inhale    L/sec
              L/sec                        Inspiratory
                                           reserve vol.


                                           Tidal vol.
                                           Exspiratory
                                           reserve vol.
                                           Residual vol.
                       Respiration speed




                                                                    1
3/18/2013




Diagnosis of lung malfunction

Diagnose stenoses with spirometer:

 No change in any volume
 Slower inhalation speed
 Slower exhalation speed




Diagnosis of lung malfunction




                      Inspiratory
                      reserve


                      Tidal
                      Exspiratory
                      reserve
                      residual




                                            2
3/18/2013




Diagnosis of lung malfunction
Diagnose obstruction with spirometer:

 Residual volume is slightly increased
 Expiratory reserve volume is slightly
 increased
 Inspiratory reserve volume is slightly
 decreased
 Little slower inhalation speed
 Slower exhalation speed




 Diagnosis of lung malfunction




                        Inspiratory
                        reserve


                        Tidal
                        Exspiratory
                        reserve
                        residual




                                                 3
3/18/2013




  Diagnosis of lung malfunction
Diagnose Emphysema with spirometer:

 Residual volume is largely increased
 Expiratory reserve volume is slightly
 increased
 Inspiratory reserve volume is largely
 decreased
 Little slower inhalation speed
 Much slower exhalation speed




  Diagnosis of lung malfunction



                       Inspiratory
                       reserve


                       Tidal
                       Exspiratory
                       reserve
                       residual




                                                4
3/18/2013




     Diagnosis of lung malfunction

    Diagnose Restriction with spirometer:

       Expiratory reserve volume is decreased
       Inspiratory reserve volume is decreased
       Little slower inhalation speed
       Little slower exhalation speed




               Gas partial pressure
Atmospheric pressure at sea level :
760 mm Hg (Mercury) = 760 torr
= 1013 millibar

Dalton’s law:
Pressure is sum of partial pressures

Partial pressure O2 =760 * 0.21 = 159

100 % water saturation at 37 C
= 47 mm Hg

The colder the water, the more gas can be
dissolved

Solubility depends on gas type




                                                        5
3/18/2013




           Gas partial pressure
Nitrogen (N2)              78.1%
Oxygen (O2)                20.9%
Argon (Ar)                 0.9%
Carbon dioxide (CO2)       0.038%
Neon (Ne)                  0.002%

Helium (He) (0.000524%) Methane (CH4) 1.79 (0.000179%) , Krypton
(Kr) (0.000114%) , Hydrogen (H2) (0.000055%) ,Nitrous oxide (N2O)
(0.00003%), Xenon (Xe) (9 × 10−6%), Ozone (O3) (0% to 7 × 10−6%)
,Nitrogen dioxide (NO2) (2 × 10−6%), Iodine (I) (1 × 10−6%), Carbon
monoxide (CO) ,Ammonia (NH3) trace




        Pressure distribution in
        the atmosphere

                     human live zone




                                                                             6
3/18/2013




Respiratory zone anatomy




      Alveolar air




                                  7
3/18/2013




      Calculation of alveolar O2
 Sample values given for air at sea level at 37°C                .




 Quantity   Description                                   Sample value
 pAO2       The alveolar partial pressure of oxygen (pO2) 107 mmHg
            The fraction of inspired gas that is oxygen
 FIO2                                                     0.21
            (expressed as a decimal).
 PATM       The prevailing atmospheric pressure           760 mmHg

            The saturated vapour pressure of water at
 pH2O       body temperature and the prevailing           47 mmHg
            atmospheric pressure
            The arterial partial pressure of carbon
 paCO2                                                    36 mmHg
            dioxide (pCO2)
 RQ         The respiratory quotient (CO 2/O2)            0.8




      Calculation of alveolar O2


The respiratory quotient (RQ) is
calculated from the ratio:
  RQ = CO2 eliminated / O2 consumed

carbon dioxide (CO2) removed
"eliminated“ from the body.




                                                                                8
3/18/2013




Calculation of alveolar O2 in La Paz




Calculation of alveolar O2 in La Paz
   Air pressure at 3640 m = 484 torr
   Water vapor in alveoli = 100 % = 47 torr
   CO2 - pressure in air ~ 0 torr
   CO2 - pressure in alveoli = 42 torr
   Fraction of O2 in air = 0.21 = 21 %
   Respiratory quotient = 0.8


   PalveolarO2 = 0.21 *(484 – 47) – (42/0.8)
                  = 39.27 torr




                                                      9
3/18/2013




              Respiratory zone




  Blood                                   Alveolar air
              Respiratory membrane




                                     Gas exchange across
                                     this surface takes place
                                     driven entirely by
                                     DIFFUSION.




Diffusion and respiratory function

Gas exchange across
respiratory membranes

-Differences in partial
  pressure
-Small diffusion distance
-Lipid-soluble gases
-Large surface area of all
  alveoli
-Coordination of blood flow
  and airflow




                                                                      10
3/18/2013




            Blood gas transport
 O2 is carried in the blood as:
 1. Dissolved gas (in plasma)
 2. Bound to hemoglobin as oxyhemoglobin (Hb O2).



                         Blood

      Alveoli




                  Hemoglobin
  Hemoglobin is composed of protein (globin)
             and heme-groups

4 globins and 4 hemes = 1 hemoglobin molecule

                 O2        Heme-group contains Fe2+



                         Remember!
                         1 O2 binds to 1 Fe




                                                            11
3/18/2013




Oxygen binding to hemoglobin
    changes its structure




    Blood O2 transport by
        hemoglobin


                4th O2
           3rd O2
       2nd O2
                    Cooperative binding of O2
     1st   O2       to hemoglobin




                                                      12
3/18/2013




       O2 content in blood

Calculation:
Concentration of Hb in blood 110 -180 g
Normal Hb-saturation = 97%
1 g Hb can bind max. 1.34 ml O2

Total O2 in blood = Hb-bound + free O2
= Hb max * saturation [%] + free O2




     Gas transport control
pH
CO2
Temperature
DPG (2,3-Bisphosphoglyceric acid)
   makes it harder for oxygen to bind hemoglobin
   and more likely to be released to adjacent tissues




                                                              13
3/18/2013




  Control of O2 in the blood




              Cyanosis
How can you get blue blood ?
Inhibit hemoglobin binding capacity by carbon
monoxid (250 times better binding to Hb)


Central cyanosis
ventilatory problem
slowing down of circulation

Peripheral cyanosis
poor circulation in the small vessels




                                                      14
3/18/2013




             Oxygen Delivery
Oxygen Delivery (DO2)
- Cardiac output (Qt)
- Hb content of blood
- Ability of the lung to oxygenate the blood


Total O2 delivered = Qt * O2 in arterial blood.
Qt = 5 L / minute,    alveoloar O2 = 20 %;
Lungs deliver 1 L of O2 to our tissues each minute.




        CO2 transport in blood

 CO2 is transported in blood…
 as HCO3- ion = bicarbonate (90 %)
 as dissolved CO2 (5 %)
 as carbamino protein complexes (5 %)


 Predominant transport mechanism of
 CO2 is as HCO3- within the red blood cells




                                                            15
3/18/2013




   CO2 transport in blood

CO2 is transported as carbonate ion

CO2 + H2O      H2CO3     H+ + HCO3-

Enzyme is Carbonic Anhydrase in RBC
Chloride shift to compensate for
bicarbonate moving in and out of RBC




Enzymatic conversion of CO2




                                             16
3/18/2013




         Regulation of breathing
     Two major descending pathways from
     the Medulla oblongata:

     1. voluntary breathing
     2. involuntary breathing




          Controls of respiration
                                                Input 1



Input consists of 3              Input 2                       Input 3

  components:
1. The central & peripheral                Medulla oblongata
                                            in the brainstem
   chemo receptors (input 1)                   (integrator)

2. The pulmonary
   mechanoreceptors (input
   2)                                       Output
                                 (via phrenic nerve)

3. Input from reticular
   activation system, cerebral     Respiratory muscles
   cortex, thalamus (input 3)




                                                                               17
3/18/2013




Brain stem breathing centers
                     Rhythmic center in formatio
                reticularis of medulla oblongata

               I-neurons (inspiration) stimulate
                           spinal motoneurons

                  E-neurons (expiration) inhibit
                                     I-neurons

                   Apneustic centre stimulates
                                     I-neurons

                   Pneumotactic centre inhibits
                            apneustic centre




 Chemo receptors provide
     sensory input
           O2, CO2 and pH are monitored

                  Arterial CO2 is the most
                         important!

            1. Central chemo receptors
               in Medulla oblongata

            2. Peripheral chemo
               receptors (aortic und
               carotid bodies) provide
               indirect input to Medulla
               oblongata




                                                         18
3/18/2013




 Motoric innervations of muscles




                  Cortical input (voluntary)




Ventilation, regulated by pH & CO2




                                                     19
3/18/2013




  Blood gas abnormalities
Oxygen toxicity:
100 % oxygen at 760 – 1500 mm Hg OK!
higher pressure > 1800 mm Hg enzyme and
nerve damage

Nitrogen narcosis (rapture of the deep):
long term exposure to high pressure >2500
mm Hg for > 1 h
like alcohol intoxication




  Blood gas abnormalities
Decompression sickness
Only happens after prolonged stay at
high pressure.
Nitrogen forms bubbles, when a diver
ascents to fast.
Obey decompression tables




                                                  20
3/18/2013




      Blood gas abnormalities

   Stagnant hypoxia: intravascular stasis.
   Decreased venous outflow of blood from
   tissue.
   Anemic hypoxia: decreased concentration
   of functional hemoglobin or low RBC count
   Hypoxic hypoxia: defective mechanism of
   oxygenation in the lungs




      Blood gas abnormalities
Arterial hypoxemia : arterial PaO2 is to low.
An arterial PaO2 less than 80 mm Hg is abnormal
Hypoxia: insufficient oxygen to carry out normal
metabolic functions. Thus, hypoxia and hypoxemia
are frequently used interchangeably.
Hypercapnia : increase in arterial PaCO2 above 40 ±
2 mm Hg
Hypocapnia : abnormally low arterial PaCO2 (less
than 35 mm Hg).




                                                            21

Contenu connexe

Similaire à dr andreas lecture 12 re-upload

09 pre hospital capnography
09 pre hospital capnography09 pre hospital capnography
09 pre hospital capnographyDang Thanh Tuan
 
09 pre hospital capnography
09 pre hospital capnography09 pre hospital capnography
09 pre hospital capnographyDang Thanh Tuan
 
Hyperbaric oxygen therapy Anaesthesia
Hyperbaric oxygen therapy AnaesthesiaHyperbaric oxygen therapy Anaesthesia
Hyperbaric oxygen therapy AnaesthesiaGaurav Joshi
 
Respiratory System physiology by Ajay Sarangi
Respiratory System  physiology by Ajay SarangiRespiratory System  physiology by Ajay Sarangi
Respiratory System physiology by Ajay SarangiAJAYSARANGI2
 
Respiratory physiology by Dr RamKrishna
Respiratory physiology by Dr RamKrishnaRespiratory physiology by Dr RamKrishna
Respiratory physiology by Dr RamKrishnaram krishna
 
08 capnometry and pulse oximetry
08 capnometry and pulse oximetry08 capnometry and pulse oximetry
08 capnometry and pulse oximetryDang Thanh Tuan
 
08 capnometry and pulse oximetry
08 capnometry and pulse oximetry08 capnometry and pulse oximetry
08 capnometry and pulse oximetryDang Thanh Tuan
 
Capnography
CapnographyCapnography
Capnographylarryide
 
Nitrous oxide, 0xygen and hyperbaric oxygen
Nitrous oxide, 0xygen and hyperbaric oxygenNitrous oxide, 0xygen and hyperbaric oxygen
Nitrous oxide, 0xygen and hyperbaric oxygenashtondionel
 
Respiratory physiology
Respiratory physiologyRespiratory physiology
Respiratory physiologyIsaias Lanzona
 
7[1].3 the concept of gaseous exchange
7[1].3   the concept of gaseous exchange7[1].3   the concept of gaseous exchange
7[1].3 the concept of gaseous exchangecikgushaik
 
7[1].3 the concept of gaseous exchange
7[1].3   the concept of gaseous exchange7[1].3   the concept of gaseous exchange
7[1].3 the concept of gaseous exchangecikgushaik
 
Physiology of Respiratory System.pptx
Physiology of Respiratory System.pptxPhysiology of Respiratory System.pptx
Physiology of Respiratory System.pptxAmyLalringhluani
 
Airway management part 1
Airway management part 1Airway management part 1
Airway management part 1Dang Thanh Tuan
 

Similaire à dr andreas lecture 12 re-upload (20)

09 pre hospital capnography
09 pre hospital capnography09 pre hospital capnography
09 pre hospital capnography
 
09 pre hospital capnography
09 pre hospital capnography09 pre hospital capnography
09 pre hospital capnography
 
Oxygentherapy MADE SIMPLE
Oxygentherapy MADE SIMPLEOxygentherapy MADE SIMPLE
Oxygentherapy MADE SIMPLE
 
Hyperbaric oxygen therapy Anaesthesia
Hyperbaric oxygen therapy AnaesthesiaHyperbaric oxygen therapy Anaesthesia
Hyperbaric oxygen therapy Anaesthesia
 
Respiratory System physiology by Ajay Sarangi
Respiratory System  physiology by Ajay SarangiRespiratory System  physiology by Ajay Sarangi
Respiratory System physiology by Ajay Sarangi
 
Respiratory physiology by Dr RamKrishna
Respiratory physiology by Dr RamKrishnaRespiratory physiology by Dr RamKrishna
Respiratory physiology by Dr RamKrishna
 
Resp.pptx
Resp.pptxResp.pptx
Resp.pptx
 
08 capnometry and pulse oximetry
08 capnometry and pulse oximetry08 capnometry and pulse oximetry
08 capnometry and pulse oximetry
 
08 capnometry and pulse oximetry
08 capnometry and pulse oximetry08 capnometry and pulse oximetry
08 capnometry and pulse oximetry
 
Capnography
CapnographyCapnography
Capnography
 
Nitrous oxide, 0xygen and hyperbaric oxygen
Nitrous oxide, 0xygen and hyperbaric oxygenNitrous oxide, 0xygen and hyperbaric oxygen
Nitrous oxide, 0xygen and hyperbaric oxygen
 
Respiratory physiology
Respiratory physiologyRespiratory physiology
Respiratory physiology
 
Respiratory Physiology
Respiratory PhysiologyRespiratory Physiology
Respiratory Physiology
 
Respiratory Physiology
Respiratory PhysiologyRespiratory Physiology
Respiratory Physiology
 
Respiratory Physiology
Respiratory PhysiologyRespiratory Physiology
Respiratory Physiology
 
7[1].3 the concept of gaseous exchange
7[1].3   the concept of gaseous exchange7[1].3   the concept of gaseous exchange
7[1].3 the concept of gaseous exchange
 
7[1].3 the concept of gaseous exchange
7[1].3   the concept of gaseous exchange7[1].3   the concept of gaseous exchange
7[1].3 the concept of gaseous exchange
 
Physiology of Respiratory System.pptx
Physiology of Respiratory System.pptxPhysiology of Respiratory System.pptx
Physiology of Respiratory System.pptx
 
RESPIR-2.PPT
RESPIR-2.PPTRESPIR-2.PPT
RESPIR-2.PPT
 
Airway management part 1
Airway management part 1Airway management part 1
Airway management part 1
 

Plus de AHS_Physio

lecture 18 dr may
lecture 18 dr may lecture 18 dr may
lecture 18 dr may AHS_Physio
 
dr hameed lecture 17
dr hameed lecture 17dr hameed lecture 17
dr hameed lecture 17AHS_Physio
 
dr hameed lecture 16
dr hameed lecture 16dr hameed lecture 16
dr hameed lecture 16AHS_Physio
 
dr.may lecture 15
dr.may lecture 15dr.may lecture 15
dr.may lecture 15AHS_Physio
 
lecture 14 dr fawzy
lecture 14 dr fawzy lecture 14 dr fawzy
lecture 14 dr fawzy AHS_Physio
 
dr fawzy lecture 13
dr fawzy lecture 13dr fawzy lecture 13
dr fawzy lecture 13AHS_Physio
 
lecture 11 dr andreas
lecture 11 dr andreas lecture 11 dr andreas
lecture 11 dr andreas AHS_Physio
 
lecture 10 dr fawizy 6/3/2013
lecture 10 dr fawizy 6/3/2013lecture 10 dr fawizy 6/3/2013
lecture 10 dr fawizy 6/3/2013AHS_Physio
 
lecture 9 dr.fawizy 4/3/2013
lecture 9 dr.fawizy 4/3/2013lecture 9 dr.fawizy 4/3/2013
lecture 9 dr.fawizy 4/3/2013AHS_Physio
 
dr fawziy 8 lecture 20/2/2013
dr fawziy 8 lecture 20/2/2013dr fawziy 8 lecture 20/2/2013
dr fawziy 8 lecture 20/2/2013AHS_Physio
 
dr.fawziy 7 lecture 18/2/2013
dr.fawziy 7 lecture 18/2/2013dr.fawziy 7 lecture 18/2/2013
dr.fawziy 7 lecture 18/2/2013AHS_Physio
 
Lecture 6.dr hameed alsarraf
Lecture 6.dr hameed alsarrafLecture 6.dr hameed alsarraf
Lecture 6.dr hameed alsarrafAHS_Physio
 
5th class dr.hameed alsarraf
5th class dr.hameed alsarraf5th class dr.hameed alsarraf
5th class dr.hameed alsarrafAHS_Physio
 
3rd class dr.ali boresliy
3rd class dr.ali boresliy3rd class dr.ali boresliy
3rd class dr.ali boresliyAHS_Physio
 
Lecture 3.. Dr. Hameed
Lecture 3.. Dr. HameedLecture 3.. Dr. Hameed
Lecture 3.. Dr. HameedAHS_Physio
 
2nd lecture dr.hameed
2nd lecture dr.hameed2nd lecture dr.hameed
2nd lecture dr.hameedAHS_Physio
 
1st lecture dr.hameed
1st lecture dr.hameed1st lecture dr.hameed
1st lecture dr.hameedAHS_Physio
 

Plus de AHS_Physio (17)

lecture 18 dr may
lecture 18 dr may lecture 18 dr may
lecture 18 dr may
 
dr hameed lecture 17
dr hameed lecture 17dr hameed lecture 17
dr hameed lecture 17
 
dr hameed lecture 16
dr hameed lecture 16dr hameed lecture 16
dr hameed lecture 16
 
dr.may lecture 15
dr.may lecture 15dr.may lecture 15
dr.may lecture 15
 
lecture 14 dr fawzy
lecture 14 dr fawzy lecture 14 dr fawzy
lecture 14 dr fawzy
 
dr fawzy lecture 13
dr fawzy lecture 13dr fawzy lecture 13
dr fawzy lecture 13
 
lecture 11 dr andreas
lecture 11 dr andreas lecture 11 dr andreas
lecture 11 dr andreas
 
lecture 10 dr fawizy 6/3/2013
lecture 10 dr fawizy 6/3/2013lecture 10 dr fawizy 6/3/2013
lecture 10 dr fawizy 6/3/2013
 
lecture 9 dr.fawizy 4/3/2013
lecture 9 dr.fawizy 4/3/2013lecture 9 dr.fawizy 4/3/2013
lecture 9 dr.fawizy 4/3/2013
 
dr fawziy 8 lecture 20/2/2013
dr fawziy 8 lecture 20/2/2013dr fawziy 8 lecture 20/2/2013
dr fawziy 8 lecture 20/2/2013
 
dr.fawziy 7 lecture 18/2/2013
dr.fawziy 7 lecture 18/2/2013dr.fawziy 7 lecture 18/2/2013
dr.fawziy 7 lecture 18/2/2013
 
Lecture 6.dr hameed alsarraf
Lecture 6.dr hameed alsarrafLecture 6.dr hameed alsarraf
Lecture 6.dr hameed alsarraf
 
5th class dr.hameed alsarraf
5th class dr.hameed alsarraf5th class dr.hameed alsarraf
5th class dr.hameed alsarraf
 
3rd class dr.ali boresliy
3rd class dr.ali boresliy3rd class dr.ali boresliy
3rd class dr.ali boresliy
 
Lecture 3.. Dr. Hameed
Lecture 3.. Dr. HameedLecture 3.. Dr. Hameed
Lecture 3.. Dr. Hameed
 
2nd lecture dr.hameed
2nd lecture dr.hameed2nd lecture dr.hameed
2nd lecture dr.hameed
 
1st lecture dr.hameed
1st lecture dr.hameed1st lecture dr.hameed
1st lecture dr.hameed
 

dr andreas lecture 12 re-upload

  • 1. 3/18/2013 Respiratory Physiology Lecture 2 Andreas W. Henkel, Ph.D. Diagnosis of lung malfunction Respiration Exhale volume Inhale L/sec L/sec Inspiratory reserve vol. Tidal vol. Exspiratory reserve vol. Residual vol. Respiration speed 1
  • 2. 3/18/2013 Diagnosis of lung malfunction Diagnose stenoses with spirometer: No change in any volume Slower inhalation speed Slower exhalation speed Diagnosis of lung malfunction Inspiratory reserve Tidal Exspiratory reserve residual 2
  • 3. 3/18/2013 Diagnosis of lung malfunction Diagnose obstruction with spirometer: Residual volume is slightly increased Expiratory reserve volume is slightly increased Inspiratory reserve volume is slightly decreased Little slower inhalation speed Slower exhalation speed Diagnosis of lung malfunction Inspiratory reserve Tidal Exspiratory reserve residual 3
  • 4. 3/18/2013 Diagnosis of lung malfunction Diagnose Emphysema with spirometer: Residual volume is largely increased Expiratory reserve volume is slightly increased Inspiratory reserve volume is largely decreased Little slower inhalation speed Much slower exhalation speed Diagnosis of lung malfunction Inspiratory reserve Tidal Exspiratory reserve residual 4
  • 5. 3/18/2013 Diagnosis of lung malfunction Diagnose Restriction with spirometer: Expiratory reserve volume is decreased Inspiratory reserve volume is decreased Little slower inhalation speed Little slower exhalation speed Gas partial pressure Atmospheric pressure at sea level : 760 mm Hg (Mercury) = 760 torr = 1013 millibar Dalton’s law: Pressure is sum of partial pressures Partial pressure O2 =760 * 0.21 = 159 100 % water saturation at 37 C = 47 mm Hg The colder the water, the more gas can be dissolved Solubility depends on gas type 5
  • 6. 3/18/2013 Gas partial pressure Nitrogen (N2) 78.1% Oxygen (O2) 20.9% Argon (Ar) 0.9% Carbon dioxide (CO2) 0.038% Neon (Ne) 0.002% Helium (He) (0.000524%) Methane (CH4) 1.79 (0.000179%) , Krypton (Kr) (0.000114%) , Hydrogen (H2) (0.000055%) ,Nitrous oxide (N2O) (0.00003%), Xenon (Xe) (9 × 10−6%), Ozone (O3) (0% to 7 × 10−6%) ,Nitrogen dioxide (NO2) (2 × 10−6%), Iodine (I) (1 × 10−6%), Carbon monoxide (CO) ,Ammonia (NH3) trace Pressure distribution in the atmosphere human live zone 6
  • 8. 3/18/2013 Calculation of alveolar O2 Sample values given for air at sea level at 37°C . Quantity Description Sample value pAO2 The alveolar partial pressure of oxygen (pO2) 107 mmHg The fraction of inspired gas that is oxygen FIO2 0.21 (expressed as a decimal). PATM The prevailing atmospheric pressure 760 mmHg The saturated vapour pressure of water at pH2O body temperature and the prevailing 47 mmHg atmospheric pressure The arterial partial pressure of carbon paCO2 36 mmHg dioxide (pCO2) RQ The respiratory quotient (CO 2/O2) 0.8 Calculation of alveolar O2 The respiratory quotient (RQ) is calculated from the ratio: RQ = CO2 eliminated / O2 consumed carbon dioxide (CO2) removed "eliminated“ from the body. 8
  • 9. 3/18/2013 Calculation of alveolar O2 in La Paz Calculation of alveolar O2 in La Paz Air pressure at 3640 m = 484 torr Water vapor in alveoli = 100 % = 47 torr CO2 - pressure in air ~ 0 torr CO2 - pressure in alveoli = 42 torr Fraction of O2 in air = 0.21 = 21 % Respiratory quotient = 0.8 PalveolarO2 = 0.21 *(484 – 47) – (42/0.8) = 39.27 torr 9
  • 10. 3/18/2013 Respiratory zone Blood Alveolar air Respiratory membrane Gas exchange across this surface takes place driven entirely by DIFFUSION. Diffusion and respiratory function Gas exchange across respiratory membranes -Differences in partial pressure -Small diffusion distance -Lipid-soluble gases -Large surface area of all alveoli -Coordination of blood flow and airflow 10
  • 11. 3/18/2013 Blood gas transport O2 is carried in the blood as: 1. Dissolved gas (in plasma) 2. Bound to hemoglobin as oxyhemoglobin (Hb O2). Blood Alveoli Hemoglobin Hemoglobin is composed of protein (globin) and heme-groups 4 globins and 4 hemes = 1 hemoglobin molecule O2 Heme-group contains Fe2+ Remember! 1 O2 binds to 1 Fe 11
  • 12. 3/18/2013 Oxygen binding to hemoglobin changes its structure Blood O2 transport by hemoglobin 4th O2 3rd O2 2nd O2 Cooperative binding of O2 1st O2 to hemoglobin 12
  • 13. 3/18/2013 O2 content in blood Calculation: Concentration of Hb in blood 110 -180 g Normal Hb-saturation = 97% 1 g Hb can bind max. 1.34 ml O2 Total O2 in blood = Hb-bound + free O2 = Hb max * saturation [%] + free O2 Gas transport control pH CO2 Temperature DPG (2,3-Bisphosphoglyceric acid) makes it harder for oxygen to bind hemoglobin and more likely to be released to adjacent tissues 13
  • 14. 3/18/2013 Control of O2 in the blood Cyanosis How can you get blue blood ? Inhibit hemoglobin binding capacity by carbon monoxid (250 times better binding to Hb) Central cyanosis ventilatory problem slowing down of circulation Peripheral cyanosis poor circulation in the small vessels 14
  • 15. 3/18/2013 Oxygen Delivery Oxygen Delivery (DO2) - Cardiac output (Qt) - Hb content of blood - Ability of the lung to oxygenate the blood Total O2 delivered = Qt * O2 in arterial blood. Qt = 5 L / minute, alveoloar O2 = 20 %; Lungs deliver 1 L of O2 to our tissues each minute. CO2 transport in blood CO2 is transported in blood… as HCO3- ion = bicarbonate (90 %) as dissolved CO2 (5 %) as carbamino protein complexes (5 %) Predominant transport mechanism of CO2 is as HCO3- within the red blood cells 15
  • 16. 3/18/2013 CO2 transport in blood CO2 is transported as carbonate ion CO2 + H2O H2CO3 H+ + HCO3- Enzyme is Carbonic Anhydrase in RBC Chloride shift to compensate for bicarbonate moving in and out of RBC Enzymatic conversion of CO2 16
  • 17. 3/18/2013 Regulation of breathing Two major descending pathways from the Medulla oblongata: 1. voluntary breathing 2. involuntary breathing Controls of respiration Input 1 Input consists of 3 Input 2 Input 3 components: 1. The central & peripheral Medulla oblongata in the brainstem chemo receptors (input 1) (integrator) 2. The pulmonary mechanoreceptors (input 2) Output (via phrenic nerve) 3. Input from reticular activation system, cerebral Respiratory muscles cortex, thalamus (input 3) 17
  • 18. 3/18/2013 Brain stem breathing centers Rhythmic center in formatio reticularis of medulla oblongata I-neurons (inspiration) stimulate spinal motoneurons E-neurons (expiration) inhibit I-neurons Apneustic centre stimulates I-neurons Pneumotactic centre inhibits apneustic centre Chemo receptors provide sensory input O2, CO2 and pH are monitored Arterial CO2 is the most important! 1. Central chemo receptors in Medulla oblongata 2. Peripheral chemo receptors (aortic und carotid bodies) provide indirect input to Medulla oblongata 18
  • 19. 3/18/2013 Motoric innervations of muscles Cortical input (voluntary) Ventilation, regulated by pH & CO2 19
  • 20. 3/18/2013 Blood gas abnormalities Oxygen toxicity: 100 % oxygen at 760 – 1500 mm Hg OK! higher pressure > 1800 mm Hg enzyme and nerve damage Nitrogen narcosis (rapture of the deep): long term exposure to high pressure >2500 mm Hg for > 1 h like alcohol intoxication Blood gas abnormalities Decompression sickness Only happens after prolonged stay at high pressure. Nitrogen forms bubbles, when a diver ascents to fast. Obey decompression tables 20
  • 21. 3/18/2013 Blood gas abnormalities Stagnant hypoxia: intravascular stasis. Decreased venous outflow of blood from tissue. Anemic hypoxia: decreased concentration of functional hemoglobin or low RBC count Hypoxic hypoxia: defective mechanism of oxygenation in the lungs Blood gas abnormalities Arterial hypoxemia : arterial PaO2 is to low. An arterial PaO2 less than 80 mm Hg is abnormal Hypoxia: insufficient oxygen to carry out normal metabolic functions. Thus, hypoxia and hypoxemia are frequently used interchangeably. Hypercapnia : increase in arterial PaCO2 above 40 ± 2 mm Hg Hypocapnia : abnormally low arterial PaCO2 (less than 35 mm Hg). 21