Respiratory Physiology introduction Daniel Hodyc Department of Physiology

Respiratory Physiology - introduction Daniel Hodyc Department of Physiology UK 2. LF

Respiratory Physiology 1. Pulmonary Ventilation 2. Mechanics of Breathing 3. Ventilation/perfusion ratio, regulation 4. Regulation of Breathing

Gas transport in lungs 1. Pulmonary ventilation - transport of gases to alveoli 2. Pulmonary diffusion factors determining gas transport across the membrane 3. Perfusion 4. Ventilation/perfusion ratio

Pulmonary ventilation 1. Partial pressure 2. Lung volumes and capacities 3. Alveolar ventilation 4. Anatomical and functional death space, effective ventilation

Partial pressure of the gas - in determined by its concentration in the mixture and by the overall pressure of the gas mixture Patm. O 2 = Patm * FO 2 Patm. O 2 = 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 expiratory reserve volume residual volume inspiratory reserve volume

Lung volumes and capacities Spirometer - measurement of lung volumes - measurement of the oxygen consumption

Measurement of residual volume and FRC - helium equilibration method C 1 * V 1 Uneven ventilation C 2 * (V 1 + V 2) Inaccurate measurement

Measurement of functional residual capacity - pletysmograph Boyl´s law: P * V = const P 1 * V 1 P 1* V 1 = P 1´* (V 1 - d. V) P 2* V 2 = P 2´* (V 2 + d. V) V 2 = FRC

Air composition in respiratory system

Alveolar ventilation of anatomic dead space 02 C 02 inspiration expiration

Alveolar ventilation

Relationship between tidal volume, frequency and effective ventilation Minute ventilation ml/min Tidal volume ml Frekvency c/s Alveolar Ventilation Anat. dead ml/min space ml/min 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 Effective ventilation %

Physiologic dead space ventilated but not perfused alveoli Bohr equation VD VT = Pa. CO 2 - PECO 2 Pa. CO 2 VT ventilation of anatomic dead space VA ventilation of physiologic dead space VAeff PECO 2 PACO 2 Pa. CO 2

Uneven ventilation The worst ventilation - apical parts

Summary - 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,

Thank you for your attention Pictures and schemes – J. B. West - Respiratory Physiology, LWW - Guyton, Hall - Textbook of Medical Physiology, 11 th