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Questions and Answers
What supplies each bronchopulmonary segment?
What supplies each bronchopulmonary segment?
Which feature is NOT characteristic of bronchioles?
Which feature is NOT characteristic of bronchioles?
What is the shape of each bronchopulmonary segment?
What is the shape of each bronchopulmonary segment?
Which type of epithelium lines the alveoli?
Which type of epithelium lines the alveoli?
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As bronchioles decrease in size, which of the following changes occurs?
As bronchioles decrease in size, which of the following changes occurs?
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What is the main function of Type I Pneumocytes?
What is the main function of Type I Pneumocytes?
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Which of the following statements about Type II Pneumocytes is true?
Which of the following statements about Type II Pneumocytes is true?
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What role does pulmonary surfactant play in the lungs?
What role does pulmonary surfactant play in the lungs?
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Which characteristic distinguishes Type I Pneumocytes from Type II Pneumocytes?
Which characteristic distinguishes Type I Pneumocytes from Type II Pneumocytes?
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What is a unique function of Type II Pneumocytes related to lung health?
What is a unique function of Type II Pneumocytes related to lung health?
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What effect does the parasympathetic nervous system have on bronchial activity?
What effect does the parasympathetic nervous system have on bronchial activity?
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Which structures does lymphatic drainage occur through?
Which structures does lymphatic drainage occur through?
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What is the composition of the tracheal wall?
What is the composition of the tracheal wall?
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Where does the trachea start and end in the body?
Where does the trachea start and end in the body?
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What is the primary function of the trachealis muscle?
What is the primary function of the trachealis muscle?
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What type of epithelium lines the trachea?
What type of epithelium lines the trachea?
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What are the two layers of pleurae surrounding the lungs called?
What are the two layers of pleurae surrounding the lungs called?
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Which cavity contains a small amount of pleural fluid?
Which cavity contains a small amount of pleural fluid?
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What is the main function of pulmonary surfactant?
What is the main function of pulmonary surfactant?
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At what gestational week is pulmonary surfactant typically produced?
At what gestational week is pulmonary surfactant typically produced?
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Which structure does NOT contribute to the blood-air barrier?
Which structure does NOT contribute to the blood-air barrier?
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What is located at the lung hila?
What is located at the lung hila?
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What is the role of corticosteroid administration in threatened premature deliveries?
What is the role of corticosteroid administration in threatened premature deliveries?
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Which vessel indicates a groove at the right hilum of the lung?
Which vessel indicates a groove at the right hilum of the lung?
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Which autonomic nervous system fibers contribute to the pulmonary plexus?
Which autonomic nervous system fibers contribute to the pulmonary plexus?
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What is the position of the lung hila in relation to the costal cartilages?
What is the position of the lung hila in relation to the costal cartilages?
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How many lobes does the right lung have?
How many lobes does the right lung have?
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What is the function of the hilum of the lung?
What is the function of the hilum of the lung?
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Which bronchus is more likely to have foreign bodies enter it?
Which bronchus is more likely to have foreign bodies enter it?
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Which structure connects the lung to the trachea and the heart?
Which structure connects the lung to the trachea and the heart?
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What is the position of the left main bronchus in relation to the aorta?
What is the position of the left main bronchus in relation to the aorta?
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What are bronchopulmonary segments classified as?
What are bronchopulmonary segments classified as?
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Which statement about the fissures of the right lung is correct?
Which statement about the fissures of the right lung is correct?
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What shape does the lung conform to within the thoracic cavity?
What shape does the lung conform to within the thoracic cavity?
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Study Notes
Anatomy of the Lungs
- Lungs are located in the lateral parts of the thoracic cavity.
- Each lung is surrounded by pleura.
- Right lung has 3 lobes; left lung has 2 lobes.
- Each lung receives a main bronchus, one pulmonary artery, and two pulmonary veins.
- These structures subdivide within the lung.
- Lungs also receive nerves and lymphatics.
- The root of the lung is where the lung connects to the trachea and heart.
- The hilum of the lung is where the bronchi and pulmonary vessels enter.
- The lung conforms to the thoracic cavity's shape; its costal surface is convex, and the diaphragmatic and mediastinal surfaces are concave.
- The apex of the lung extends about 2.5cm above the clavicle.
The Principal Bronchi
- The right main bronchus is shorter, wider, and more vertical than the left.
- Inhaled foreign objects are more likely to enter the right lung due to this structure.
- Before entering the right lung's hilum, the right main bronchus branches off into a superior lobar bronchus.
- Upon entering the hilum, it further divides into middle and inferior lobar bronchi.
- The left main bronchus is narrower, longer, and more horizontal.
- It is located below the arch of the aorta and divides into a superior and inferior lobar bronchus.
The Bronchial Tree
- The trachea branches into the right and left main bronchi.
- The main bronchi further divide into lobar bronchi, and then segmental bronchi.
Lobes and Fissures
- The right lung is slightly larger than the left lung.
- The right lung is divided into 3 lobes by oblique and horizontal fissures.
- The horizontal fissure runs horizontally across the fourth costal cartilage.
- The oblique fissure runs from the inferior border to the posterior border of the lung.
- The left lung is divided into 2 lobes by an oblique fissure.
The Bronchopulmonary Segments
- These are the anatomical, functional, and surgical units of the lung.
- Each lobe is supplied by a lobar bronchus.
- A lobar bronchus divides into segmental bronchi, supplying the bronchopulmonary segments.
- Each bronchopulmonary segment has connective tissue, a segmental bronchus branch, and pulmonary vein/artery tributaries.
- The segments are pyramidal in shape, with the apex towards the lung root.
The Bronchioles
- Segmental bronchi repeatedly divide, becoming smaller.
- They lose their cartilage and become bronchioles.
- Bronchioles are less than 1mm in diameter.
- They lack cartilage and are lined with a ciliated columnar epithelium.
- Bronchioles contain smooth muscle fibers.
- Bronchioles develop into terminal bronchioles and eventually respiratory bronchioles, where gas exchange begins.
The Bronchioles (continued)
- As bronchioles get smaller, the epithelium becomes simple ciliated columnar.
- Goblet cells decrease, and cartilage is absent.
- There’s a thickening of smooth muscle.
- Very small bronchioles have a simple cuboidal epithelium.
The Bronchopulmonary Segments (continued)
- Respiratory bronchioles branch into alveolar ducts leading to alveolar sacs.
- Alveoli are chambers lined by simple squamous epithelium, facilitating gas exchange between air and capillaries.
The Lung Hila
- Lung hila are at the level of the 3rd and 4th costal cartilages and at T5, T6, and T7.
- The hila contain the entrances for pulmonary vessels, bronchi, lymphatics, and nerves.
- Right hilum is grooved by azygos vein and superior vena cava.
- Left hilum is grooved by the aorta, aortic arch, and subclavian vessels.
Nerve supply to Lungs
- Autonomic nerve fibers (sympathetic and parasympathetic) form pulmonary plexuses at the hila.
- The plexuses divide into anterior and posterior plexuses.
- Parasympathetic nerves induce cough reflexes and cause bronchoconstriction and vasodilation.
- They also stimulate mucous glands.
- Sympathetic nerves cause bronchodilation and vasoconstriction.
Lymphatic Drainage
- Lymphatic drainage occurs via superficial and deep plexuses.
- Draining onto bronchopulmonary lymph nodes, then tracheobronchial nodes.
- Drainage continues via the bronchomediastinal lymph trunk.
The Trachea
- The trachea is approximately 10 cm long and 2.5cm in diameter (15cm during inspiration)
- It's a fibrous tube with U-shaped cartilage rings.
- The posterior free ends of the incomplete cartilage rings are joined by trachealis muscle.
- It begins at the level of the cricoid cartilage of the larynx.
- It terminates at the level of the sternal angle (T4/5), where it divides into the right and left main bronchi.
- Lined by pseudostratified ciliated columnar epithelium.
The Trachea (continued: Relations)
- Posterior: Esophagus
- Anterior: Sternum and Thymus, Left Brachiocephalic vein, Aortic arch and its branches
- Right Side: Azygos Vein, Right Vagus
- Left Side: Aortic arch, Left common carotid and left subclavian arteries, Left vagus and left phrenic nerves
The Pleurae
- Pleura comprises two layers – parietal and visceral – surrounding the lungs.
- Parietal pleura lines the thoracic cavity, diaphragm, mediastinal surfaces, and cervical pleura.
- Visceral pleura covers the outer surfaces of the lungs and extends into the interlobar fissures.
- The two layers meet at the hilum, forming the pulmonary ligament.
The Pleurae (continued)
- The pleural cavity is a potential space between the parietal and visceral pleura, containing pleural fluid.
- Types of parietal pleura: cervical, diaphragmatic, mediastinal.
- Recesses: costodiaphragmatic and costomediastinal.
The Alveoli
- Respiratory bronchioles branch into alveolar ducts and sacs.
- Alveoli contain simple squamous epithelium to facilitate gas exchange.
Alveolar Cells
- Type I pneumocytes form the majority (90%) of the alveolar surface, are thin, and form the blood-air barrier.
- Type II pneumocytes (septal cells) are cuboidal, secrete surfactant, and are important for maintaining alveoli stability.
- Macrophages/dust cells remove foreign particles from the alveoli.
Pulmonary Surfactant
- Surfactant is a phospholipid and protein fluid.
- It decreases surface tension in alveoli, helping them inflate during inspiration.
- It prevents collapse during expiration.
- Secreted constantly and removed by type I pneumocytes and macrophages. A key component dipalmitoylphosphatidylcholine (DPPC).
Bronchopulmonary Segments (continued: Specific Segment Names)
- Segments are listed by lung and lobe in a specified order by the notes.
Blood-Air Barrier
- Thin layer of surfactant.
- Cytoplasm of Type I pneumocytes.
- Basement membrane of pneumocytes.
- Connective tissue.
- Basement membrane of capillary endothelial cells.
- Cytoplasm of endothelial cells.
The Lung in Disease (Examples)
- Pleural effusions involve fluid accumulation in the pleural cavity.
- Lobar pneumonia exhibits lung inflammation.
- Pneumothorax involves air in the pleural space, collapsing the lung.
- Lung malignancy (cancer) involves cancerous growth in the lung.
- Chronic Obstructive Pulmonary Disease (COPD) is characterized by chronic lung inflammation and damage (often connected to smoking).
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Description
Test your knowledge on the anatomy and function of the respiratory system. This quiz covers important structures like bronchioles, alveoli, and the role of various cells in lung health. Understand the complexities of bronchopulmonary segments and the significance of pulmonary surfactant.
