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Respiratory System
Respiratory System• Consists of the respiratory and conducting parts• Respiratory part
– Site of gas exchange – Consists of bronchioles, alveolar ducts, and alveoli
• Conducting part – Provides rigid conduits for air to reach the sites of gas
exchange– Includes all other respiratory structures (e.g., nose,
nasal cavity, pharynx, trachea)
• Respiratory muscles: diaphragm and other muscles that promote ventilation
Major Functions of the Respiratory System
• To supply tissues with oxygen and dispose of carbon dioxide
• Respiration: four distinct processes must happen
– Pulmonary ventilation: moving air into and out of the lungs
– External respiration: gas exchange between the lungs and the blood
– Internal respiration: gas exchange between blood and tissues
– Transport: transport of oxygen and carbon dioxide between the lungs and tissues
General Anatomy
• Upper respiratory tract:
• The nose, Mouth, pharynx, and Larynx.
• Lower respiratory tract:
• The trachea, Bronchi, Alveoli, and Lungs.
– The thoracic cavity consists of:
• Right and left pleural cavities (the parietal pleura lines the
thoracic cavity, and the visceral pleura adheres directly to the
lung tissue.
• Mediastinum.
Respiratory Zone
• Begins as terminal bronchioles, feed into respiratory
bronchioles.
• Respiratory bronchioles lead to alveolar ducts, then to
terminal clusters of alveolar sacs composed of alveoli
• Approximately 300 million alveoli:
– Account for most of the lungs’ volume
– Provide great surface area for gas exchange
Respiratory Zone
Gross Anatomy of the Lungs
• Lungs occupy all of the thoracic cavity except the
mediastinum
– Root or Hilum: site of vascular and bronchial
attachments
– Costal surface: anterior, lateral, and posterior
surfaces in contact with the ribs
– Apex: narrow superior tip
– Base: inferior surface that rests on the diaphragm
Hilum of the lungs
Blood Supply to Lungs• Lungs are perfused by pulmonary and bronchial arteries.
1- Pulmonary arteries: – Supply systemic venous blood to be oxygenated– Ultimately feed into the pulmonary capillary network
surrounding the alveoli– Pulmonary veins: carry oxygenated blood back to the
heart
2- Bronchial arteries:
– Provide systemic blood to the lung tissue
– Arise from aorta and enter the lungs at the hilus
– Supply all lung tissue except the alveoli
Pleurae
• Thin, double-layered serosa
• Parietal pleura
– Covers the thoracic wall and superior face of the diaphragm
– Continues around heart and between lungs
• Visceral pleura
– Covers the external lung surface
– Divides the thoracic cavity into three chambers
• The central mediastinum
• Two lateral compartments, each containing a lung
Mediastinum• Divided into: anterior, middle, and posterior
portions.
– Anterior mediastinum contains: the thyroid and thymus glands.
– Middle mediastinum contains: heart and great vessels, esophagus, and trachea.
– Posterior mediastinum contains: descending aorta and spine.
Chest X-Ray ReviewImaging techniques used to investigate chest
pathology include:
Plain X-Ray film
Computed Tomography (CT Scan)
Magnetic Resonance Imaging (MRI)
Ultrasound (US)
Angiography
Radiographic signs
• Silhouette sign: opacity near the heart so you can not detect the heart boarder easily.
• Notes from the radiographs: opacity frontal and heart frontal so lesion is frontal.
Negative Silhouette
• Lesion Posterior.
• Q. Lesion anterior or posterior?
Air Bronchogram• Opacity in the lung contains a tree filled with air (bronchi
contains air but alveoli opaque).
• Lesion arises from the lung not chest wall or pleura or mediastinum.
• Air bronchogram=alveolar pathology=consolidation (lung filled with liquid).
• Pulmonary nodule: well defined lesion less than 3cm.
• Mass: well defined lesion more than 3cm.
To interpret chest x-raydifferentiate between
• Focal lesion
• Diffuse lesion
Focal lesions
• Nodules
• Masses
• Cavities: sphere filled with air.
• Patches: opacity contains air bronchogram.
Nodules maybe due tomost common
• Tuberculoma
• Hamartoma
• Bronchogenic carcinoma
• Metastases
(multiple nodules or solitary)
• AVM
• Hydatid cyst
• Benign nodule (Hamartoma and Tuberculoma): If we have pulmonary nodule and the edge is smooth and contains calcification.
Bronchogenic carcinoma
• Speculated margin nodule= malignancy.
• Upper lobe distribution 70%.
Bronchogenic carcinoma
• Lateral view showing the speculated margin.
Hydatid cyst• Single or multiple lesions
filled with water.
• Thin non enhancing margin.
• Abscess: thick enhancing margin, usually contains air.
X- ray lung abscess
CT is needed to show if the lesions are cystic or solid
Patch • An ill defined lesion with air
bronchogram.
• Air bronchogram: air filled bronchi passing through opaque lung.
• Pulmonary lesion.
• Alveolar pathology.
• Consolodation.
• Patch may be due to:
• Pneumonia or infarction.
Pneumonia
• is an inflammatory condition of the lung affecting primarily alveoli.
• It is usually caused by infection with viruses or bacteria.
• Typical symptoms include a cough, chest pain, fever, and difficulty breathing
Pneumonia is accompanied by Consolidation
Diffuse lung disease
• We have 4 radiographic pattern:
1. Reticular pattern
e.g. Pneumonia, Bronchitis: Confluent small ill-defined densities produce a reticular pattern.
2. Ground glass pattern: increase in density in areas of ground glass and air trapping in lower lobes in patients with hypersensitivity pneumonitis (inflammation of lung tissue).
Pneumonia is pneumonitis combined with consolidation (is a region of (normally compressible) lung tissue that has filled with liquid) due to infection.
3. Cystic lesions: air filled cysts.
4. Nodular pattern