Respiratory Physiology
- introduction
Daniel HodycDepartment of Physiology
UK 2.LF
1. Pulmonary Ventilation
2. Mechanics of Breathing
3. Ventilation/perfusion ratio, regulation
4. Regulation of Breathing
Respiratory Physiology
1. Pulmonary ventilation- transport of gases to alveoli
2. Pulmonary diffusionfactors determining gas transport
across the membrane
3. Perfusion
4. Ventilation/perfusion ratio
Gas transport in lungs
1. Partial pressure
2. Lung volumes and capacities
3. Alveolar ventilation
4. Anatomical and functional death space, effective ventilation
Pulmonary ventilation
Partial pressure of the gas
- in determined by its concentration in the mixture and by the overall pressure of the gas mixture
PatmO2 = Patm * FO2
PatmO2 = 740 torr * 0,21
- in the liquid - partial pressure of the gas component, which is balanced with the liquid
Lung volumes and capacities
tidal volume
inspiratory reserve volume
expiratory reserve volume
residual volume
Lung volumes and capacities
Spirometer - measurement of lung volumes - measurement of the oxygen consumption
Measurement of residual volume and FRC
- helium equilibration method
Uneven ventilation Inaccurate measurement
C1 * V1 C2 * (V1 + V2)
Measurement of functional residual capacity
- pletysmograph
Boyl´s law: P * V = const
P1* V1 = P1´* (V1 - dV)
P2* V2 = P2´* (V2 + dV)
V2 = FRC
P1* V1
P2* V2
Air composition in respiratory system
Alveolar ventilation
02
C02
ventilation of anatomic dead space
inspiration expiration
Alveolar ventilation
Relationship between tidal volume, frequency and
effective ventilationMinute
ventilation
ml/min
Tidalvolume
ml
Frekvency
c/s
AlveolarVentilatio
n ml/min
Ventilation
Anat. deadspaceml/min
Effectiveventilatio
n%
8000 250 32 3200 4800 40
8000 500 16 5600 2400 70
8000 1000 8 6800 1200 85
Why not to breathe with minimal frequency?
Work of breathing
Measurement of anatomic dead space
Fowler´smethod
- insp - 100% 02
- exp - nitrogen concentrationmeasurement
VD
Physiologic dead spaceventilated but not perfused alveoli
PECO2 PACO2 PaCO2
VT
VA
VAeff
ventilation of anatomic dead space
ventilation of physiologic dead space
VD
VT
=PaCO2 PECO2
PaCO2
- Bohr equation
Uneven ventilation
The worst ventilation - apical parts
- lung volumes measurable by spirometer (VT,IRV,ERV)
- RV, FRC - measurable by He, plethysmograph
- anatomic dead space
- effective ventilation and respiratory frequency,
work of breathing
- physiologic dead space,
Summary
Thank you
for your
attention
Pictures and schemes – J.B.West - Respiratory Physiology, LWW - Guyton, Hall - Textbook of Medical Physiology,
11th