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
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