Adobe Systems Physiology department 1 Physiology of the respiratory system. Adobe Systems Physiology department 2 Questions for the oral exam ̶A22: Hypoxia and ischemia ̶A25: Lung ventilation, volumes, measurement ̶A26: Dead space, measurement ̶A27: Resistance of airways, measurement ̶A28: Maximal respiratory flow - volume curve (spirogram) ̶A45: Alveolar surface tension. Surfactant ̶A46: Compliance of lungs. Respiratory work. Pneumothorax ̶A47: Composition of atmospheric and alveolar air. Gas exchange in lungs and tissues ̶A48: Transport of O2. Oxygen - haemoglobin dissociation curve. Transport of CO2 ̶A49: Regulation of ventilation ̶A50: Respiratory responses to irritants Adobe Systems Physiology department 3 A22: Hypoxia and ischemia ̶Hypoxia is a general name for a lack of oxygen in the body or individual tissues ̶Ischemia, meaning insufficient blood flow to a tissue, can also result in hypoxia ̶The most common types of hypoxia: ̶Hypoxic ̶Transport (anemic) ̶Ischemic (stagnation) ̶Histotoxic O2 O2 O2 O2 ERY ERY ERY: ♀ 3.4 – 4.4 * 1012/l ♂ 4.5 – 5.5 * 1012/l pO2: 21kPa Adobe Systems 4 A22: Hypoxia and ischemia ̶Hypoxic: ̶physiological: stay at higher altitudes ̶↓ pO2; N Ery ̶pathological: hypoventilation during lung or neuromuscular diseases ̶↓ ventilation; N pO2; N Ery ̶Transport (anemic): ̶reduced transport capacity of blood for oxygen (anemia, blood loss) ̶N pO2; ↓ Ery/Hb ̶Ischemic (stagnation): ̶restricted blood flow to tissue (heart failure, obstruction of an artery) ̶N pO2; N Ery ̶Histotoxic ̶cells are unable to utilize oxygen (cyanide poisoning) ̶N pO2; N Ery ̶ Adobe Systems Physiology department 5 A25: Lung ventilation, volumes, measurement ̶Ventilation, or breathing, is the movement of air through the conducting passages between the atmosphere and the lungs ̶Principle: determination the air flow velocity from the measured pressure differences between the inner and outer spirometer membranes, the volumes being calculated (PowerLab spirometry) ̶ Adobe Systems Physiology department 6 A25: Lung ventilation, volumes, measurement ̶Tidal volume (TV) – the volume of air that enters the lungs during each inspiration (or the volume that is exhaled during every expiration). ̶Inspiratory reserve volume (IRV) – the maximal amount of additional air that can be drawn into the lungs by determined effort after a normal inspiration at rest. ̶Expiratory reserve volume (ERV) – the additional amount of air that can be exhaled from the lungs by determined effort after a normal expiration. ̶Residual volume (RV) – the volume of air still remaining in the lungs after the most forcible expiration possible. ̶ V [l] Vt (0,5 l) IRV (2,5 l) ERV (1,5 l) RV (1,5 l) Adobe Systems Physiology department 7 A25: Lung ventilation, volumes, measurement Lung capacity: ̶VC = VT + IRV + ERV ̶TLC = VC + VC ̶FRC = ERV + RV ̶IC = IRV + VT ̶EC = ERV + VT ̶ Vt (0,5 l) IRV (2,5 l) ERV (1,5 l) RV (1,5 l) V [l] Dynamic lung volumes: ̶VE ̶MMV ̶ Adobe Systems Physiology department 8 A25: Lung ventilation, volumes, measurement Dynamic lung volumes ̶ V [l] Time [s] 1 s FEV1 ―FVC – the maximum volume of air that can be exhaled after maximum inhale ―FEV1 – the volume of air exhaled with the greatest effort in 1 second after maximum inhale ―FEV1/FVC (%) – Tiffeneau index – around 0,8 (80 %) Adobe Systems Physiology department 9 A25: Lung ventilation, volumes, measurement 1 s V [l] Time [s] 1 s V [l] Time [s] FEV1 FEV1 FVC > FVC Obstructive lung disease (FVC=N; FEV1=↓) ―tracheal stenosis ―astma bronchiale ―CHOPN ―tumor Restrictive lung disease (FVC=↓; FEV1=N) Pulmonarzy etiology ―pulmonary fibrosis ―lung resection ―pulmonary edema ―pneumonia Extrapulmonary etiology ―ascites ―kyphoscoliosis ―burns ―high diaphragm condition Adobe Systems Physiology department 10 A25: Lung ventilation, volumes, measurement V1 c1 V2=RV+V1 c2 Helium dilution method – residual volume Adobe Systems Physiology department 11 A28: Maximal respiratory flow - volume curve (spirogram) PEF MEF25% MEF50% MEF75% TLC IRV Vt ERV RV IRC VC FRC RV •PEF – peek expiratory flow; the highest speed of air flow at peak of exhale •MEF – maximum expiratory flow rates at different FVC levels, which is still to be exhaled (75 %, 50 % and 25 % of FVC) Principle: the measurement of the air flow velocity according to the speed of the turbine and the volumes are calculated (Cosmed). Adobe Systems Physiology department 12 A26: Dead space, measurement Adobe Systems Physiology department 13 A26: Dead space, measurement Adobe Systems Physiology department 14 A27: Resistance of airways, measurement Pneumotachograph: ―tubes of the same diameter, parallel arranged ―measures the differences in air pressure at the beginning and end of the pneumotachograph in proportion to the velocity of the inhaled or exhaled air > > > Adobe Systems Physiology department 15 A46: Compliance of lungs. Respiratory work. Pneumothorax parietal pleura visceral pleura pleural fluid pleural pressure alveolar pressure Adobe Systems Physiology department 16 A46: Compliance of lungs. Respiratory work. Pneumothorax ̶According to etiology: ̶traumatic pneumothorax (due to an injury) occurs if the chest wall is perforated or during an injury of the esophagus, bronchi, and during rib fractures. ̶spontaneous pneumothorax ̶primary idiopathic pneumothorax (without any known cause) may occur in tall healthy young men with an incidence of pneumothoraxes in the family, ̶secondary pneumothorax arises as a consequence of lung diseases (such as COPD or cystic fibrosis), ̶iatrogenic pneumothorax (due to medical procedures) occurs during invasive medical examinations such as transparietal aspiration biopsy, subclavian vein catheterization, or mechanical ventilation with positive pressure. ̶artificially induced (deliberate) pneumothorax is used during thoracoscopy, an endoscopic examination the thoracic cavity. ̶According to the communication of the pleural space with its surroundings ̶open pneumothorax (when the hole in the pleural space remains open, the air in the pleural cavity moves back and forth with each breath of the patient) ̶closed pneumothorax (when a small opening through which air enters the pleural cavity closes) ̶valvular pneumothorax (the tissue of the lungs or the chest wall covers the hole in such a way that a valve emerges, this valve allows air to flow inside during inspiration, but it prevents the air from leaving the pleural cavity during exhalation). ̶ Adobe Systems Physiology department 17 A45: Alveolar surface tension. Surfactant ―pneumocytes typ II ―reduces the surface tension depending on the size of the alveolus ―increases lung compliance, reduces breathing work The Laplace law (in constant tension): the alveolus with bigger radius has lower pressure ® the air would move from a smaller alveolus to a bigger one ® collapse of smaller alveoli ― r T P 2 = Adobe Systems Physiology department 18 A46: Compliance of lungs. Respiratory work. Pneumothorax Respiratory system resistance ̶Elastic resistance: ̶elastic fibers ̶alveolar surface tension ̶Nonelastic resistance: ̶viskose resistance ̶airway resistance Respiratory work: ̶Elastic ̶Viskose ̶Work of airway resistance Adobe Systems Physiology department 19 A46: Compliance of lungs. Respiratory work. Pneumothorax V (l) Pt (kPa) TLC RV Pt: Patm and Ppl Pt: Palv and Ppl Pt: Patm and Palv Adobe Systems Physiology department 20 A46: Compliance of lungs. Respiratory work. Pneumothorax V (l) Pt (kPa) TLC RV Pt (kPa) V (l) Respiratory work: 1 – elastic 2 – viscos 3 – airway resistance Adobe Systems Physiology department 21 Case report Herman Neiswander is a 65-year-old retired landscape architect. One cold January morning, he decided to warm his car in the garage. Forty minutes later, Mr. Neiswander’s wife found him slumped in the front seat of the car, confused and breathing rapidly. He was taken to a nearby emergency department, where he was diagnosed with acute carbon monoxide (CO) poisoning and given 100% O2 to breathe. An arterial blood sample had an unusual cherry-red color. The values obtained in the blood sample are given in table below. pO2 660 mm Hg (normal, 100 mm Hg) pCO2 36 mm Hg (normal, 40 mm Hg) % O2 50 (normal, 95–100) Pulse oximetry 100% Adobe Systems Physiology department 22 Case report 1. Why was Mr. Neiswander’s O2 saturation reduced to 50%? 2. If Mr. Neiswander’s % O2 saturation was 50%, why was his pulse oximetry value 100%? 3. What percentage of the heme groups on his hemoglobin were bound to CO? 4. O2–hemoglobin dissociation curve. What effect did CO poisoning have on the affinity of hemoglobin for O2? 5. How did CO poisoning alter O2 delivery to Mr. Neiswander’s tissues? 6. What was the rationale for giving Mr. Neiswander 100% O2 to breathe? Adobe Systems 23 A47: Composition of atmospheric and alveolar air. Gas exchange in lungs and tissues. BAROMETRIC PRESSURE IN SEA LEVEL 1 atmosphere = 760 mm Hg 1 kPa = 7,5 mm Hg (torr) O2 20.95 % FO2 @ 0,21 N2 78.09 % FN2 @ 0,78 CO2 0.03 % FCO2 @ 0,0004 COMPOSITION OF DRY ATMOSPHERIC AIR Adobe Systems Physiology department 24 A47: Composition of atmospheric and alveolar air. Gas exchange in lungs and tissues. Adobe Systems Physiology department 25 A48: Transport of O2. Oxygen - haemoglobin dissociation curve. Transport of CO2 O2 is transported in two forms : ―physically dissolved(1%) ―in chemical bond with Hb (99%) ―Fetal hemoglobin(2α, 2g) ―Methemoglobin (Fe3+) ―Carboxyhemoglobin (CO) ―Carbaminohemoglobin (CO2) ―Oxyhemoglobin (O2) ―Deoxyhemoglobin (without any gases) Adobe Systems Physiology department 26 A48: Transport of O2. Oxygen - haemoglobin dissociation curve. Transport of CO2 Dissociation curve of Hb is influenced by: ―pH of blood ―pCO2 of blood ―Temperature ―Concentration of 2,3 - BPG Adobe Systems Physiology department 27 A48: Transport of O2. Oxygen - haemoglobin dissociation curve. Transport of CO2 CO2 is transported in next forms : ―physically dissolved(5 %) ―in the form of bicarbonate anions (85%) ―in chemical bond with Hb (10%) CO2 + H2O H2CO3 KAH H+ + Hb HCO3- Cl- CO2 H+ + HCO3 - CO2 + H2O Hb H2CO3 KAH Cl- CO2 Adobe Systems Physiology department 28 A49: Regulation of ventilation Adobe Systems Physiology department 29 A49: Regulation of ventilation Adobe Systems Physiology department 30 A49: Regulation of ventilation Adobe Systems Physiology department 31 A49: Regulation of ventilation Adobe Systems 32 A50: Respiratory responses to irritants The lungs are protected from damage by: ̶presence of hair (vibrissae) in the nasal cavity (traps dust particles) ̶presence of ciliary epithelium covered with mucus (cilia moving mucus in one direction - into the pharynx) ̶pulmonary alveolar macrophages ̶presence of antibodies in bronchial secretion (IgA) Reflexes: ̶Herring-Breuer reflexes (inflation/deflation) ̶Sneeze reflex ̶Cough reflex ̶Hiccup ̶Yawn ̶ ̶ Adobe Systems 33 A50: Respiratory responses to irritants Adobe Systems Physiology department 34 Herring-Breuer reflexes (inflation/deflation) ̶a. keeps the lungs from over-inflating with inspired air ̶pulmonary stretch R – vagus nerve – medulla – inhibition of inspiration and initiation of expiration ̶b. serves to shorten exhalation when the lung is deflated ̶pulmonary stretch R – vagus nerve – the pontine center ̶ A50: Respiratory responses to irritants