Adobe Systems Physiology department 1 Respiratory system. Compendium. 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 + RV ̶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 Obstruction lung disease (FVC=N; FEV1=↓) ―tracheal stenosis ―astma bronchiale ―CHOPN ―tumor Restrictive lung disease (FVC=↓; FEV1=N) Pulmonary etiology ―pulmonary fibrosis ―lung resection ―pulmonary edema ―pneumonia Extrapulmonary etiology ―ascites ―kyphoscoliosis ―burns ―high diaphragm condition FUNCTIONAL INVESTIGATION OF THE LUNGS TIMED VITAL CAPACITY (FEV1 - forced expiratory volume per 1 s) PULMONARY MINUTE VENTILATION RMV (respiratory minute volume) at rest (0.5 l x 12 breathes/min = 6 l/min) PEAK EXPIRATORY FLOW RATE (PEFR) (~10 l/s) MAXIMAL VOLUNTARY VENTILATION (MVV) (125-170 l/min) 10 V [l] Čas [s] 1 s FEV1 0 1 2 3 4 5 1 s V [l] Čas [s] 0 1 2 3 4 5 1 s V [l] Čas [s] Healthy people Obstruction disease FVC physiology values FVC physiology values FEV1=80% FEV1 lower than 70% Restriction disease FVC lower than physiology values FEV1 – as physiology value Adobe Systems Physiology department 11 A25: Lung ventilation, volumes, measurement V1 c1 V2=RV+V1 c2 Helium dilution method – residual volume Adobe Systems Physiology department 12 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). 6 IN HEALTHY INDIVIDUALS both spaces are practically identical DEAD SPACE TOTAL GAS VOLUME NOT EQUILIBRATED WITH BLOOD (without exchange of gasses) ANATOMICAL dead space - volume of air passages FUNCTIONAL (total) dead space ANATOMICAL dead space + total VOLUME of ALVEOLI without functional capillary bed f = 12/min VT = VA + VD VD part of tidal volume remaining in the dead space ~ 150 ml 5 4.2 l/min 6 l/min ALVEOLAR VENTILATION VA · = VA x f 1.8 l/min DEAD SPACE VENTILATION VD · = VD x f PULMONARY MINUTE VENTILATION V ∙ = VT x f VT tidal volume ~ 500 ml VA part of tidal volume entering alveoli ~ 350 ml DEAD SPACE – nitrogen test (force inspiration of pure O2, follow slowly expiration with monitoring of concentration of nitrogen) Adobe Systems Physiology department 16 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 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 = 16 P pressure r radius T surface tension LAW OF LAPLACE spherical structures EXPANSION OF ALVEOLI P1 > P2 P1 P2 COLLAPSE OF ALVEOLI - ATELECTASIS P r T r T P 2 = ? PATHOLOGY 17a SURFACTANT SURFACE TENSION LOWERING AGENT obr 5 přech ALVEOLAR EPITHELIAL CELLS macrofage fatty acids, choline, glycerol, amino acids, etc.) surfactant surfactant cycle exocytosis of lamellar bodies PHOSPHOLIPID dipalmitoyl fosfatidyl cholin TYPE II specialized granular epithelial cells PRODUCTION OF SURFACTANT TYPE I thin epithelial cells DIFFUSION OF GASSES EFFECT MAINLY IN THE EXPIRED POSITION Adobe Systems Physiology department 20 A46: Compliance of lungs. Respiratory work. Pneumothorax parietal pleura visceral pleura pleural fluid pleural pressure alveolar pressure Graf změny intrapleur tlaku Graf změny objemu Graf změny plícního tlaku Obrzměny intrapleur tlaku Silbernagl pulmonalis parietalis PLEURA +0.1 kPa -0.1 kPa -0.3/-0.5 kPa -0.6/-0.8 kPa Adobe Systems Physiology department 22 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 23 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 FORCES PARTICIPATING IN RESPIRATION 12 QUIET RESPIRATION EXPIRATION - only passive (elastic) forces are in action INSPIRATION - active forces of inspiratory muscles prevail PASSIVE FORCES represented by: ACTIVE FORCES performed by respiratory muscles lungs elasticity chest elasticity Forces acting on the lung 1.elasticity of lung (elastic recoil) (collapsing force) 2.Lung surface tension (collapsing force) 3.Chest wall recoil (opening force) 4.Intrapleural pressure-IPP (opening force) mage result for forces acting on the lung Lung recoil and chest wall recoil mage result for forces acting on the lung Intrapleural pressure elated image Major forces acting on the lung Important points ØIntrapleural pressure > Lung recoil à Lung Expands ØIntapleural pressure < lung recoil à lung collapse ØIntrapleural pressure = Lung recoil à lung size constant Transmural pressure elated image Adobe Systems Physiology department 30 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 31 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 32 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 33 A47: Composition of atmospheric and alveolar air. Gas exchange in lungs and tissues. Adobe Systems Physiology department 34 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 35 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 36 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 37 A49: Regulation of ventilation Adobe Systems Physiology department 38 A49: Regulation of ventilation •They can be divided into three main groups: • –dorsal respiratory group – placed bilaterally on the dorsal side of the medulla oblongata, only inspiratory neurons, sending axons to motoneurons of inspiratory muscles (diaphragm, external intercostal muscles; their activation=inspiration, their relaxation=expiration; participates on inspiration at rest and forced inspiration – –ventral respiratory group - located on the ventrolateral part of the medulla oblongata, the upper part: neurons whose axons of motor neurons activate the main and auxiliary inspiratory muscles; the lower part: expiratory neurons which innervate expiratory muscles (internal intercostal muscles). Neurons in this group operate only during forced inspiration and forced expiration. – –Pontine respiratory group - pneumotaxic center - dorsally placed on top of the pont, contributes to the frequency and depth of breathing; affects the activity of respiratory neurons in the medulla oblongata. Chemical factors affecting the respiratory center: •Central chemoreceptors -on the front side of the medulla -sensitive only to increase of arterial pCO2 (by increasing H+ •(intracerebral fluid) - - - -Notice: -central chemoreceptor are stimulated by other types of acidosis (lactate acidosis, ketoacidosis) •Peripheral chemoreceptors •– located in the aortic and carotid bodies •-primarily sensitive to decrease in arterial pO2, particularly to decrease of O2 under 10-13 kPa in the arterial blood. •They convey their sensory information to the medulla via the vagus nerve and glossopharyngeal nerve. • •Mechanism of action: Decreased ATP production in mitochondria leads to depolarization of receptors membrane and to excitation of chemoreceptor http://www.medicine.mcgill.ca/physio/resp-web/sect8.htm, Adobe Systems Physiology department 42 A49: Regulation of ventilation Adobe Systems Physiology department 43 A49: Regulation of ventilation Adobe Systems 44 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 45 A50: Respiratory responses to irritants Adobe Systems Physiology department 46 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 • Upraveno dle: Poopesko Peter a kol. (1990) •Hering – Breuer ´s reflex in animal experimentH • 47 • • • TRACHEA N. VAGUS A. CAROTIS ENDOTRACHEAL CANNULA • • 48 HERING-BREUER REFLEX HB před vagotomií001 • REFLEX STOP BREATHING • ARTEFAKTS • ARTEFAKTS • • 49 Changes of breathing after VAGOTOMY klidové dých po vagotomii004 • • • • One-side VAGOTOMY Both-side VAGOTOMY inspirium exspirium