Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
1
XVII. Pneumography
XX. Pneumotachography
Physiology I – practice
Autumn, weeks 10-12

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
2
Pneumography
̶= a method for registration of respiratory movements
̶Respiratory muscles
̶Main inspiratory muscles: diaphragm and external intercostal muscles
̶Accessory inspiratory muscles: sternocleidomastoid musculus and a group of scalene muscles
̶Expiratory muscles: internal intercostal muscles and anterior abdominal wall muscles
̶Inspiration – active process (contraction of respiratory muscles)
̶Expiration – a passive process at rest (elasticity of the lungs pulls the chest wall back to the
expiratory position), and forced exhalation is an active process (use of expiratory muscles)
̶

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
3
Pneumography
inspiration
expiration

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
4
Chemical regulation of ventilation
̶Ventilation = tidal volume * respiratory rate
̶The volume of air ventilated over time (l/min)
̶Respiratory rate in pneumography – determined by the duration of the whole respiratory cycle
(breathing interval, BI), duration of inspiration (Ti) and expiration (Te)
̶Depth of breathing in pneumography – amplitude of breathing movements (Amp)
̶Chemical control of ventilation leads to a change in depth and frequency of breathing based on
chemoreceptor information
̶
̶Chemoreceptors
̶Central – cells in the medulla oblongata near the respiratory centre
̶Peripheral – carotid and aortic
Amp
Ti
Te
BI

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
5
Central chemoreceptors
̶Located near the respiratory centre in the medulla oblongata
̶CO2 passes the blood-brain barrier into the cerebrospinal and intercellular fluids of the brain
CO2 + H2O → CHO3- + H+
̶Increased concentration of H+ in cerebrospinal fluid stimulates chemoreceptors → increased
ventilation
̶

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
6
Peripheral chemoreceptors
̶They contain two types of cells
̶Type I: located beside nerve fibres
̶Type II: glia (each one surrounds 4-6 type I cells)
̶Registration of pO2 levels dissolved in the blood plasma over time
̶Stimulation by a decrease in pO2 or by a decrease in blood flow
̶Peripheral receptors also register pCO2 and pH
Type II cell
Type I cell (glomus)
Afferent fibres of n. IX

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
7
Dead space
̶Air volume in the conductive airway area where no gas exchange with blood occurs
̶Anatomical DS: volume of the respiratory system outside the alveoli (150-200 mL)
̶Functional (physiological) DS: the volume of air that does not participate in gas exchange with
the blood – includes non-perfused alveoli
̶In healthy individuals, both dead spaces are the same
̶

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
8
Partial pressures of gases (mmHg)
̶in different parts of the respiratory and circulatory systems

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Pressures in lungs
nádech výdech
Visceral pleura
Parietal pleura
Pleural cavity –  between parietal and visceral pleura
Pleural
fluid
Intraalveolar (pulmonary) pressure
Atmospheric pressure
(now 0)
Intrapleural pressure (always negative)
The volume of inhaled air
http://worldartsme.com/images/happy-lungs-clipart-1.jpg

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
10
Lung compliance C
3
2
1
0
-1
80 120 160
Forced inspiration curve
Relaxation pressure curve
Forced expiration curve
Position at rest
(relaxation volume)
-80 -40 0 40
Pulmonary pressure (mmHg)
 (0 = atmospheric pressure)

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
11
Statistical evaluation – in general
̶Mann-Whitney test
̶Nonparametric sequential test, it compares samples A and B
̶Null hypothesis H0: sample A do not differ from sample B
̶Alternative hypothesis HA: sample A is bigger or smaller than sample B
̶Statistical significance of α (usually α = 0.05 or 0.01)
̶The probability of error, in other words, that we reject H0 based on the selection, but in reality
H0 is true
̶Test results:
̶The test is not significant = confirmation of H0: we did not confirm the difference between A and
B
̶The test is significant with significance α = rejection of H0: we confirmed that there is a
difference between A and B

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
12
Statistical evaluation – an example
̶Sample A: Amp at rest, sample B: Amp after exercise
̶Null hypothesis H0: Amp at rest will be the same as Amp after the exercise
̶Alternative hypothesis HA: Amp at rest is bigger or lower than Amp after exercise
̶We compare T1 ́-T1 with the table values for α while the number of elements n = 6. Possible
results:
̶T1 ́-T1 < 13 → we do not reject H0 at the significance level of α = 0.01, i.e. we have not shown
that Amp at rest differed from Amp after exercise
̶T1 ́-T1 > 13 → we reject H0 at the significance level of α = 0.05, i.e. we have shown that Amp at
rest differs from Amp after exercise (logically it should be higher after exercise)
̶T1 ́-T1 > 16 → we reject H0 at the significance level of α = 0.01, i.e. we have shown that Amp at
rest differs from Amp after exercise (logically it should be higher after exercise)
̶
Amp
Ti
Te
BI

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
13
Pneumotachography

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
14
Pneumotachography
̶Pneumotachography is a method enabling the estimation of airway resistance. It measures the
pressure difference between two ends of a tube through which the examined person breathes.
̶
̶An increased value of airway resistance indicates obstruction of the airways.

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
15
Poiseuille-Hagen law

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Airway resistance

Adobe Systems
Department of Physiology, Faculty of Medicine, Masaryk University
17
Principle of pneumotachography
pneumotachograph tube
valve
lung
trachea

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0
U [V]
Pp
Palv
t [s]
U [V]
M
marker
inspirium
expirium
Valve closing at the start of inspirium/expirium
Pp
Palv