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Radiographic Physiology Respiratory System Educational Objectives 1. Name the organs of the respiratory system, and discuss their functions. 2. Trace the pathway of air through the respiratory system. 3. Discuss the mechanism of breathing. 4. Differentiate between external and internal respiration 5. Explain how the gases transport into the blood. 6. Identify the different lung volumes during respiration 7. State the common pathologies affecting respiratory system 8. Identify alternative radiological methods for imaging the respiratory system. References 1. Text book of radiographic positioning and related anatomy; by Kenneth L.Bontrager,6th edition. 2. Introduction to Human Anatomy and Physiology: by Eldra Pearl Solomon:W.B.Saunders Company 3. Handbook of Anatomy and physiology for Students of Medical Radiation Technology: Mallett.M:Jaspar Websites http://www6.district125.k12.il.us/science/anatomy/ http://www.innerbody.com/htm/body.html http://www.e-radiography.net/ http://www.getbodysmart.com/index.htm 4 Respiratory System Function: obtain O2 & eliminate CO2 Air Pathway: 1. Nasal cavities (or oral cavity) 2. Pharynx 3. Trachea 4. Bronchi 5. Bronchioles 6. Alveoli (functional units( Mechanism: ventilation (inhalation, exhalation) Mechanism of Breathing Intercostals muscles + Contraction Contraction 1. Diaphragm moves downward 1. Elevation of ribs & sternum 2. 3. Antero-posterior dimension of thoracic cavity air pressure in lungs Diaphragm 2. 3. Vertical dimension of thoracic cavity Air pressure in lungs 4. Air moves into lungs 4. Air moves into lungs Inspiration (Active process) Mechanism of Breathing Exchange of Gases External respiration: o Air in alveoli and blood in pulmonary capillaries o Inhaled air: 21% oxygen, 0.04% carbon dioxide o Exhaled air: 16% oxygen, 4.5% carbon dioxide Internal respiration o Blood in systemic capillaries and body cells In the alveolar capillaries: • O2 diffuses from the alveoli into the blood & • CO2 from the blood into the alveoli. In the tissues capillaries: the mechanism is reverse Transport of Gases in the blood Oxygen: 1. Bound to hemoglobin (98.5%), released to cells as needed. 2. Dissolved in the plasma (1.5%) Carbon dioxide: From the body cells back to the lungs as: 1. Bicarbonate (60%), blood pH. 2. Carbamino-hemoglobin (30%) 3. Dissolved in the plasma (10%) Lung Volumes ◙ Respiratory rate: about 15 cycles per minute ◙ Tidal volume (TV) : amount of air which passes into and out the lungs during each cycle of quiet breathing (about 500 ml) ◙ Anatomical dead space: amount of air which does not take part in gas exchange (about 150 ml) ◙ Inspiratory reverse volume (IRV): the extra volume of air that can be inhaled into the lungs during maximal inspiration ◙ Expiratory reserve volume (ERV): the largest volume of air which can be expelled from the lungs during maximal expiration ◙ Vital capacity: the maximum volume of air which can be moved into and out of the lungs (VC) VC = TV + IRV + ERV Control of respiration ◙ Respiratory centre : • Control rate and depth • In the brain stem (medulla oblongata and pones) • Motor impulses to phrenic and intercostals nerves ◙ Chemo-receptors: • Stimulated more by CO2 levels than by O2 levels • Central: in medulla oblongata • Peripheral: in aortic arch and carotid arteries ◙ Other • • • • factors: Speech, singing Emotional (crying, laughing, fear) Drugs (sedative) Sleep Respiratory Disorders Pulmonary function affected by conditions that: Cause resistance to air flow Limit proper expansion of chest Conditions directly affecting respiratory system: Infection Injury Allergy Cancer Imaging Methods Plain Chest Radiograph Computed Tomography Magnetic Resonance Imaging Ultrasound Radionuclide Lung Scanning Positron emission tomography Pulmonary Angiography Imaging Methods Plain Radiographs - PA & Lateral ( Routine) - Supine valuable in infants and ill patients - Erect detects gas and fluid level under the diaphragm Imaging Methods CT scans Essential modality in evaluation of respiratory diseases Excellent details of mediastinal masses Identify the presence of secondary deposits CT showing secondary deposits in the lungs. Imaging Methods CT scans * High resolution CT(HRCT) with thin slices 1-2mm useful in the detection of pulmonary diseases such as fibrosis and bronchiectasis HRCT showing extensive lung fibrosis Imaging Methods CT scans CT angiography to visualize the pulmonary arterial and venous circulation to demonstrate: (e.g. Pulmonary embolism) CT scan of the pulmonary arteries (CTPA showing emboli in the right main pulmonary artery Imaging Methods • • Lung scans (NM) Perfusion scanning with technetium 99m Ventilation scanning with inhaled radioactive gas. ( NM ) lung scan Imaging Methods Ultrasound *Ultrasound of the chest determines the presence of pleural effusion * small amount of fluids can be located for aspiration through biopsy under ultrasound guidance. Ultrasound showing effusion Imaging Methods MRI scans * Not valuable for visualization of the lungs ( CT is superior) * Useful in evaluation of : - lung masses - Aortic dissection - Staging bronchial carcinoma if vascular invasion is suspected THANK YOU
