Respiratory Physiology L1 & 2 2024 BAU Student PDF

RESPIRATORY PHYSIOLOGY Respiratory physiology Respiration Oxygen supply to tissue & CO2 removal. ? ++ GUYTON & HALL LATEST EDITION  COMPONENTS PULMONARY VENTILATION (P497-506) PULMONARY CIRCULATION (P509-p516) DIFFUSION OF GASES/GAS EXCHANGE(P517-526) GASES TRANSPO...

RESPIRATORY PHYSIOLOGY Respiratory physiology Respiration Oxygen supply to tissue & CO2 removal. ? ++ GUYTON & HALL LATEST EDITION  COMPONENTS PULMONARY VENTILATION (P497-506) PULMONARY CIRCULATION (P509-p516) DIFFUSION OF GASES/GAS EXCHANGE(P517-526) GASES TRANSPORT (P527-536) REGULATION (P539-546).. PHYSIOLOGY LEARNING (SPECIFIC AIMS) OBJECTIVES 1.Illustrate microscopic and macroscopic structure of the pulmonary system 2.List functions of respiratory system 3.Define external respiration & list it's steps 4.Explain pressure gradient from atmospheric air down to alveoli during inspiration 5.List muscles involved in creating a sub-atmospheric pressure within the lung during inspiration 6.List the non-respiratory functions of the lung. 7.Explain intra-pleural pressure creation. 8.Define alveolar and trans-pulmonary pressures. 9.Illustrate changes in intra-pleural, alveolar, trans-pulmonary, pressures 10.Illustrate changes in lung volumes 11.Explain tissue elements and the alveolar surface tension. PHYSIOLOGY LEARNING (SPECIFIC AIMS) OBJECTIVES 12.Define lung compliance 13.Explain physical principles of airway resistance. 14.Define spirometry lung volumes. capacities. 15.Assess normal lung function test 16.Illustrate the significance of the major lung volumes and capacities. 17.Describe the techniques used to determine the residual volume. 18.Define forced expiratory volumes and the differentiation between obstructive & restrictive respiratory dysfunction 19.Describe pulmonary and alveolar ventilation 20.Explain anatomical and physiological dead space 21.Illustrate the value of physiological dead space.. 22.Explain the effect of breathing patterns on alveolar ventilation PHYSIOLOGY LEARNING (SPECIFIC AIMS) OBJECTIVES 23.Explain regional differences in pulmonary ventilation. 24.Explain the mechanism of regional differences in ventilation. 25.Compare the pulmonary to systemic circulations 26.Illustrate pressures gradient in the pulmonary vascular system 27.Explain the uneven distribution of blood flow through the lungs 28.Describe the fluid balance mechanism that causes pulmonary edema 29.Define the concept of gas partial pressure. 30.Describe PO2 & PCO2 in inspired air, anatomical dead space, alveolar air, and expired air. 31.Describe arterial and venous PO2 and PCO2. 32.Explain diffusion of O2 and CO2 through the respiratory membrane. 33.Illustrate mechanisms of hypoxemia:hypoventilation, diffusion limitation, and shunt PHYSIOLOGY LEARNING (SPECIFIC AIMS) OBJECTIVES 34.Illustrate the concept of ventilation-perfusion inequality 35.Explain the effect of ventilation-perfusion inequality on decreasing overall gas exchange 36.Describe forms of O2 transport in the blood. 37.Explain O2 – hemoglobin dissociation curve. 38.Describe factors affecting O2 – hemoglobin dissociation curve. 39.Explain Bohr effect 40.Describe forms of CO2 transport in the blood. 41.Explain Haldane effect 42.Explain the central control of ventilation 43.Describe sensors; various chemoreceptors that provide the respiratory center with information 44.Describe the integrated responses to CO2, hypoxia, and pH PHYSIOLOGY LEARNING (SPECIFIC AIMS) OBJECTIVES PRACTICAL 1.Illustrate the role of spirometer in measurements of lung volumes. 2.Explain the purpose of performing PFT 3.Explain the normal lung volumes & capacities. 4.Compare the effect of age, gender, body height, and race 5.Illustrate the recording of lung volumes & VC, FVC, FEV1, FEV%, PEFR, FEF25% - 75% 6.Justify how they are used to differentiate obstructive from restrictive respiratory dysfunction Respiration O2 supply to tissue & CO2 removal HOMEOSTASIS (BODY GASES) 1.GASES AIR/FLUID 2.CIRCULATION 3.TRANSPORT Pulmonary Anatomy generation Diameter Length Number Area cm2 0 1.8 12 1 2.54 trachea bronchi 1.2 4.8 1 2 Conducting zones 2.33 2 0.83 1.9 4 2.13 3 0.56 0.8 8 2.0 bronchioles 4 0.45 1.3 16 2.48 5 0.35 1.07 32 3.11 terminal bronchioles      16 0.06 0.17 6*104 180 17 respiratory 18 bronchioles respiratory zones Transitional and 19.05 0.10 5*104 103 20 alveolar ducts 21 22 alveolar sacs 23 0.04 0.05 8*106 104  Airway Resistance Main resistance in normal healthy conditions is found in larger bronchioles and bronchi near trachea (relatively few of them) Lumen diameter is the detrimental factor of resistance -In disease smaller bronchioles contract, - Edema and mucus in the lumen Control of Bronchiolar Diameter Nervous – Sympathetics 2 receptors dilate – Parasympathetics Acetylcholine constrict Humoral – Histamine, acetylcholine » Constrict – Adrenergic ( agonists) » Relax  Respiration Oxygen supply to tissue & Carbon dioxide removal Respiration involves (1) Pulmonary ventilation, (2) Diffusion of oxygen (O2) and carbon dioxide (CO2) between the alveoli and the blood (3) Blood transport of oxygen and carbon dioxide (4) Regulation of ventilation and other facets of respiration.  Pulmonary Ventilation Inflow and outflow of air between the atmosphere and the lung alveoli Review Properties of Gases Pressure= force/area Absolute pressure: in relation to complete vacuum Gage pressure: in relation to atmospheric pressure Review Gas Laws Dalton's Law In a gas mixture the pressure exerted by each individual gas in a space is independent of the pressure exerted by other gases. Patm=PH2O+PO2+PN2 Pgas=% total gases * Ptotal Boyle's Law P1V1=P2V2 Review Gas Laws Ficks Law defines diffusion of gas GAS Diffusion= Area*ΔPressure *Diffusion Coefficient /Distance Diffusion Coefficient = Solubility/(Molecular weight)½ Due to continuous suction of fluid to lymphatic system (PRIMARY) AIR INFLOW AIR OUTFLOW Diaphragm : is the muscle of quiet breathing Contraction → Inspiration Relaxation + elastic recoil of the lung and chest cage and abdominal structures compresses → Expiration Muscles of respiration Inspiratory muscles: Expiratory muscles Elevate chest cage Pull chest cage down 1.External intercostals 1.Abdominal recti (most important) (dual effect) 2.Sternocleidomastoid 2.Internal intercostals 3.Anterior serrati 4.Scaleni Mechanics of Respiration/Inhalation P atm P alveolar P alveolar Inhalation due to expansion of Rest chest cavity (Boyles law)  Mechanics of Respiration Muscles of Respiration Inspiration (1) Resting condition – Diaphragm Diaphragm Active – Diaphragm Mechanics of Respiration Muscles of Respiration INSPIRATION (2) External Intercostals Active condition Spine – Diaphragm – External intercostals ribs Mechanics of Respiration Expiration (1) Resting condition Passive process elastic properties of lung Mechanics of Respiration Expiration(2) Active Abdominals decrease chest volumes Active exhalation abdominal compression Active inspiration abdominal relaxation Mechanics of Respiration Expiration (3) Spine Internal Intercostals Active Internal intercostals ribs Movement of Air In and Out of Lungs Pleural Pressures – Resting -5 cm H20 – Inspiration -8 cm H20 Alveolar Pressure – Resting 0 cm H20 – Inspiration -1 cm H20 – Expiration 1 cm H20 Compliance – ΔV/ΔP 200 ml/cm H20 (1 cm H20 ~ 0.7 mmHg)  Pressure and Volume Changes During Breathing.50 Volume Change.25 (liter) 0 +2 Alveolar pressure 0 -2 Transpulmonary Pressure (cm/H2O) Pressure -4 -6 Pleural pressure -8 Inspiration Expiration Transpulmonary pressure: ΔP between alveoli & pleural space  Compliance of Lungs Determined by elastic forces Elastic forces Exhalation – lung tissue Lung Volume – surface tension Inhalation -4 -8 Change in Pleural Pressure Compliance of Lungs Elastic forces of the lung I. Elastic forces of the lung tissue II. Elastic forces by the surface tension Compliance of Lungs I. Elastic forces of the lung tissue Elastin and collagen fiber Is effective in one third of the whole lung compliance Compliance of Lungs Compliance of Lungs II. Elastic forces by the surface tension – Attraction of water molecules at air-water interface – Will result in collapse of alveoli – Prevented by surfactant – 1/12 to ½ is the surface tension in the alveoli in presence of surfactant as compared to pure water Surfactant -A complex mixture of several phospholipids, proteins, and ions -Secreted by type II alveolar epithelial cells -Active agent in water, part of the molecule dissolves while the remainder spreads over the surface of the water in the alveoli -It greatly reduces the surface tension of water -Prevents collapse of the thin film of water covering the alveoli → KEEPS THE ALVEOLI OPEN Microscopic Anatomy of Lobule of Lungs → ← → ← ↑↑↑ Surfactant Prevents collapse of the lung Pressure in sphere=2XSurface tension/radius →Small alveoli have more pressure So air will move to large alveoli Lung collapse (in surfactant absence) Surfactant has variable effect on surface tension according to sphere(alveoli) size Compliance of thoracic cage Compliance of both lung and thoracic cage is 50% of the lung compliance alone Lung & thorax compliance per cm H2O=110 ml Lung compliance alone per cm H2O= 200 ml Pulmonary Volumes Pulmonary Volumes/Capacities Pulmonary Volumes Tidal Volume (TV) Inspiratory Reserve Volume (IRV) Expiratory Reserve Volume (ERV) Residual Volume (RV) Pulmonary Capacities Inspiratory capacity (TV+IRV) Functional residual capacity (ER+RV) Vital Capacity (ERV+TV+IRV) Total lung capacity (RV+VC) Timed Volumes Minute Respiratory Volume – Tidal volume * respiratory rate Alveolar Ventilation – (Tidal volume-dead space) * resp rate  FRC MEASUREMENT HELIUM DILUTION METHOD: Indirect measurement technique A spirometer of known volume is filled with air mixed with helium at a known concentration Start breathing from the spirometer at the end of normal expiration Apply conservation of mass and dilution concept to calculate FRC From FRC, – RV can be calculated after measuring the expiratory reserve volume – All capacities can be calculated/ measured -Known volume -Known amount of helium added -Start inspiration at the end of quiet expiration Dead Space ANATOMICAL – 150 ml PHYSIOLOGICAL – Depends on ventilation-perfusion ratio Definitions of Dead Space Anatomic Dead Space Physiologic Dead Space Low Blood Flow  Measurements of Dead Space Dead space air is expired first