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Radiographic Physiology
Respiratory System
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.
Educational Objectives
4
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
Websiteshttp://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
References
Air Pathway: Air Pathway:
1.1. Nasal cavities (or oral Nasal cavities (or oral
cavity) cavity)
2.2. Pharynx Pharynx
3.3. Trachea Trachea
4.4. BronchiBronchi
5.5. Bronchioles Bronchioles
6.6. Alveoli (functional unitsAlveoli (functional units((
Respiratory System
FunctionFunction: : obtain Oobtain O22 & eliminate CO & eliminate CO22
Mechanism:Mechanism: ventilation (inhalation, exhalation)ventilation (inhalation, exhalation)
ContractionContraction
Mechanism of Breathing
InspirationInspiration(Active process)(Active process)
Intercostals musclesIntercostals muscles
1.1. Elevation of ribs & sternumElevation of ribs & sternum
2222 Antero-posterior Antero-posterior dimension dimension of thoracic cavityof thoracic cavity
2222 air pressure in lungsair pressure in lungs
4.4. Air moves into lungsAir moves into lungs
DiaphragmDiaphragm
ContractionContraction1.1. Diaphragm moves downwardDiaphragm moves downward
2222 Vertical dimension of Vertical dimension of thoracic cavitythoracic cavity
2222 Air pressure in lungsAir pressure in lungs
4.4. Air moves into lungsAir moves into lungs
++
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
cells22In the alveolar capillariesIn the alveolar capillaries : :
• OO2 2 diffuses from the alveoli into the blood & diffuses from the alveoli into the blood &• COCO22 from the blood into the alveoli. from the blood into the alveoli.
22In the tissues capillariesIn the tissues capillaries:: the mechanism is reversethe mechanism is reverse
Transport of Gases in the bloodOxygenOxygen::
1.1. Bound to hemoglobin (98.5%), released to cells Bound to hemoglobin (98.5%), released to cells as needed.as needed.
2.2. Dissolved in the plasma (1.5%)Dissolved in the plasma (1.5%)Carbon dioxideCarbon dioxide::
From the body cells back to the lungs as: From the body cells back to the lungs as:
1.1. Bicarbonate (60%), blood pH. Bicarbonate (60%), blood pH.
2.2. Carbamino-hemoglobin (30%)Carbamino-hemoglobin (30%)
3.3. Dissolved in the plasma (10%)Dissolved in the plasma (10%)
Lung Volumes
◙◙ Respiratory rate:Respiratory rate: about 15 cycles per minuteabout 15 cycles per minute
◙◙ Tidal volume (TV) Tidal volume (TV) : : amount of air which passes into and out the amount of air which passes into and out the
lungs during each cycle of quiet breathing (about 500 ml)lungs during each cycle of quiet breathing (about 500 ml)
◙◙ Anatomical dead space:Anatomical dead space: amount of air which does not take part in amount of air which does not take part in gas exchange (about 150 ml)gas exchange (about 150 ml)
◙◙ Vital capacityVital capacity:: the maximum volume of air which can be the maximum volume of air which can be moved into and out of the lungs (VC)moved into and out of the lungs (VC)
VC = TV + IRV + ERVVC = TV + IRV + ERV
◙◙ Inspiratory reverse volume (IRV):Inspiratory reverse volume (IRV): the the extra volume of air that extra volume of air that can be inhaled into the lungs during maximal inspirationcan be inhaled into the lungs during maximal inspiration
◙◙ Expiratory reserve volume (ERV):Expiratory reserve volume (ERV): the largest volume of air the largest volume of air which can be expelled from the lungs during maximal expirationwhich can be expelled from the lungs during maximal expiration
Control of respiration
◙◙ Respiratory centreRespiratory centre ::• Control rate and depthControl rate and depth• In the brain stem (medulla oblongata and pones)In the brain stem (medulla oblongata and pones)• Motor impulses to phrenic and intercostals nervesMotor impulses to phrenic and intercostals nerves
◙◙ Chemo-receptorsChemo-receptors::• Stimulated more by Stimulated more by COCO22 levels than by levels than by O O22 levels levels • Central: in medulla oblongataCentral: in medulla oblongata• Peripheral: in aortic arch and carotid arteriesPeripheral: in aortic arch and carotid arteries
◙◙ Other factorsOther factors::• Speech, singing Speech, singing • Emotional (crying, laughing, fear)Emotional (crying, laughing, fear)• Drugs (sedative)Drugs (sedative)• SleepSleep
Respiratory DisordersRespiratory 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
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 lungsCT 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 fibrosisHRCT 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 showingCT scan of the pulmonary arteries (CTPA showing
emboli in the right main pulmonary arteryemboli in the right main pulmonary artery
Imaging Methods
Lung scans (NM)• Perfusion scanning with technetium 99m• Ventilation scanning with inhaled radioactive gas.
) ) NMNM ( ( lung scanlung 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 effusionUltrasound 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
Imaging Methods
THANK YOU
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