RESPIRATORY FUNCTIONS MECHANICS OF RESPIRATORY SYSTEM GAS TRANSPORT RESPIRATORY SYSTEM 16 P pressure r radius T surface tension LAW OF LAPLACE 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 obr 13 přech cut nucleus RED BLOOD CELL O2 O2 O2 Hb HbO2 CO2 CO2 CO2 ~1 µm 23 ALVEOLAR-CAPILLARY (RESPIRATORY) MEMBRANE ALVEOLAR-CAPILLARY (RESPIRATORY) MEMBRANE interstitial space ALVEOLAR AIR PO2 = 100 PCO2 = 39 (mm Hg) alveolar epithelial cell time interval of erythrocyte contact with respiratory membrane at rest PULMONARY CAPILLARY diameter about 5 µm nucleus capillary endothelial cell DIFFUSION OF GASES obr 16 přech cut PO2 PCO2 PO2 100 PCO2 40 mm Hg venous blood PO2 40 PCO2 46 mm Hg 40 100 60 80 mm Hg 24 time 0.75 s time interval of contact of erythrocyte with respiratory membrane at rest Δ PO2 @ 60 mm Hg Δ PCO2 @ 6 mm Hg equalization with alveolar pressures PO2 100 PCO2 40 mm Hg TIME COURSE OF CAPILLARY PO2 AND PCO2 DURING GRADUAL EQUILIBRATION WITH ALVEOLAR AIR Control of ventilation https://sleep.sharepoint.com/siteimages/Chapter%203.png •Breathing is an automatic process that takes place unconsciously. Automaticity of breathing comes from regular (rhythmic) activity of groups of neurons anatomically localized in the medulla and its vicinity. •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+ ) - - - -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, Modulation of respiratory output Major parameters for feedback control – classical gases:pO2, pCO2, pH In additin to these, the respiratory system receives input from two other major sources: 1. variety of stretch and chemical/irritant receptors that monitor the size of airways and the presence of noxious agentsreceptors in respiratory system 2. Higher CNS centers that modulate respiratory activity for the sake of nonrespiratory activities Irritants receptors on mucose of respiratory system – rapidly adapting Stimulus: agens - chemical substances (histamin, serotonin, prostaglandins, ammonia, cigarette smoke). Respons: increase mucus secretion, constriction of larynx and brochus C-fibre receptors (juxtacapillary=J receptors)– free nerve ending of n.vagus (unmyelinated axon) in intersticium of bronchus and alveolus; Stimulus: Mechanical irritans (pulmonary hypertension, pulmonary oedema)+chemical Response: hypopnoe, rapid shallow breathing, bronchoconstriction, cough Stretch receptors slowly adapting (mechanoreceptors in tracheobronchial tree that detect the changes in lung volume by sensing the stretch receptors of the airway wall), inform to brain about the lung volume to optimize respiratory; its irritants triggered decrese activity of respiratory centre – Hering-Breuer´s reflexes. (protecting the lungs from overinflation/deflation) Baroreceptors – suppresses activity of respiratory centre Irritants of proprioreceptors of muscles, tendons during active and pasive movements of limbs Influenced activity of respiratory neurons (increase minute ventilation during work load) Limbic system, hypothalamus – strong pain, emotion Tractus corticospinalis =cortex – activated RC during work load temperature • F:\FRVŠ\FILM FOTO FINAL\001.jpg • • 19 • Upraveno dle: Poopesko Peter a kol. (1990) • • 20 • • • TRACHEA N. VAGUS A. CAROTIS ENDOTRACHEAL CANNULA • • 21 HERING-BREUER REFLEX HB před vagotomií001 • REFLEX STOP BREATHING • ARTEFAKTS • ARTEFAKTS • • 22 VAGOTOMY klidové dých po vagotomii004 • • • • One-side VAGOTOMY Both-side VAGOTOMY inspirium exspirium Periodic breathing •It is not regular, rhythmic, but respiration occurs in periods ("a moment to breathe, take a moment to not breathe„) • •CHEYNE-STOKES •BIOT‘S •„gasping“ •KUSSMAUL THANK YOU FOR YOUR ATTENTION C:\Documents and Settings\ja2\Dokumenty\Obrázky\bílé vánoce.jpg Merry Christmas and Happy New Year