Respiratory SystemAnatomyRespiratory System AnatomyNasal PassagesGross Anatomy of LungsLungsLungsLungs in the Chest CavityLobulesVentilationVentilationMuscles of RespirationInspirationPressure Changes in Pulmonary VentilationexpirationInspiration & ExpirationPneumothoraxhemothoraxRespiratory VolumesLung VolumesPathologies Associated with VentilationFactors That Influence Air FlowTerminologyGas ExchangeAlveolar Capillary MembraneGas ExchangeGas LawsExternal RespirationPartial Pressure ChangesInternal RespirationGas TransportOxygen Hemoglobin SaturationO2 –CO2 Dissociation CurveBohr EffectpH and Pco2 EffectsTemperature EffectsCarbon Dioxide TransportGas Exchange – External RespirationGas Exchange – Internal RespirationControl of RespirationRespiratory Center in the BrainNormal and Forceful BreathingFactor That Influence RespirationRespiratoryNerves & VesselsRegulation of breathingPrinciples of Biomedical Systems & DevicesPBS&D – Fall 2004 – Polikar http://engineering.rowan.edu/~polikar/CLASSES/ECE404Principles of Biomedical Systems & DevicesLecture 16The Respiratory SystemDr. Maria TahamontRespiratory System The function of the Respiratory System is gas exchange 3 basic processes:ª Ventilationª External respirationª Internal respirationAnatomy  Generally consists of upper and lower respiratory structures Upper respiratory includes nasal passages, pharynx and associated structures Lower respiratory includes larynx, trachea, bronchi, bronchioles, alveoliRespiratory System Anatomy Can also classify the anatomy functionally Conduits for air flow- nasal passages all the way down to terminal bronchioles Gas exchange areas- respiratory bronchioles and alveoliNasal PassagesGross Anatomy of LungsLungs Two lungs located in thoracic cavity Right lung has three lobes, left lung has 2 lobes Major blood vessels, nerves, lymph vessels and bronchi enter on medial surface of each lung at the hilus Each lung is covered by a serous membrane called the pleura, the visceral pleura covers the surface of the lung and the parietal pleura lines the inside of the chest wall Pleural fluid lubricates the two pleural surfacesLungsLungs in the Chest CavityLobulesVentilation Ventilation is the mechanical process of moving air (breathing) Air flow follows pressure gradients The pressures to consider are outside the body and inside the thoracic cavity Since the pressure outside the body doesn’t change, the pressure inside mustVentilation Two processes: inspiration and expiration (inhalation and exhalation) Inspiration is an active process Normal expiration is a passive process Can have forced expirationMuscles of RespirationInspiration During inspiration the pressure in the thoracic cavity becomes negative relative to the pressure outside the body This is accomplished by the contraction of the respiratory muscles, primarily the diaphragm and the intercostal muscles Contraction of these muscles increases the volume of the thoracic cavity and decreases the pressurePressure Changes in Pulmonary Ventilationexpiration Normal expiration is caused by the elastic recoil of the lung Lung is full of elastic connective tissue When it is inflated the elastic tissue stretches  Once the force that is causing the inflation is removed the elastic tissue goes back to its resting shape Doesn’t completely collapse because of the pleura and the dynamic connection between the lung and the chest wallInspiration & ExpirationPneumothoraxhemothoraxRespiratory Volumes Measured with a spirometer Tidal volume – amount of air moved in and out of lungs during normal breathing Inspiratory reserve volume – amount of air inspired over normal tidal inspiration at maximal effort Expiratory reserve volume – amount of air expired over normal tidal expiration at maximal effort Vital capacity – total amount of air moved in and out of lungs at maximal effort Residual volume – air left in lung after maximal expiration Total lung capacity – vital capacity plus residual volumeLung VolumesPathologies Associated with Ventilation Two basic types of diseases interfere with ventilation Restrictive diseases – these are related to an inability to inflate the lungs  Obstructive diseases – these are related to difficulty in getting air out of the lungsFactors That Influence Air Flow Surface tension – the tendency of the alveoli to collapse –countered by surfactant Compliance – the relative ease of inflation- dependent on elastic tissue  Air way resistance – air movement against the walls of the tubes-related to diameter of airwaysTerminology Eupenea – normal breathing Dyspnea – abnormal breathing Apnea – cessation of breathingGas Exchange Gas exchange depends on pressure gradients – in this case the pressure differences across the alveolar capillary membrane for oxygen and carbon dioxide All gas exchange in any capillary bed depends on diffusionAlveolar Capillary Membrane Alveoli are the small air sacs that make up the greater portion of the lung Consist of simple squamous epithelium (one layer of flat cells and a basement membrane) and a few specialized cells (Type II epithelial cells and alveolar macrophages) Completely surrounded by extensive capillaries which are made up of endothelial cells (one layer of flat cells and a basement membrane)Gas ExchangeGas Laws Dalton’s Law of Partial Pressure- each gas in a mixture of gases exerts a pressure independent of the other gases in the mixturePT=PO2+PCO2+PN2+PH2O Henry’s Law- the quantity of a gas that can dissolve in a liquid is proportional to the partial pressure and the solubility coefficientPressure=______PGAS______Solubility Coefficient CO2is more soluble than O2so the concentration gradient for CO2will be considerably smaller than the gradient for O2 O2is less soluble so the concentration gradient for O2will be considerably greater than for CO2External Respiration Gas exchange between the air in the lung and the blood in alveolar capillaries O2is high in the air and low in the blood so O2diffuses from air into blood CO2is low in the air and high in the blood so CO2diffuses from blood to the airPartial Pressure ChangesInternal Respiration Gas exchange between blood in systemic capillaries and working tissue O2is high in the blood and low in the tissue so O2diffuses from blood into tissue CO2is low in the blood and high in the tissue so