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

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