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40 Cards in this Set
- Front
- Back
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What are the 4 components of the respiratory passages?
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1. Respiratory bronchioles
2. Alveolar Ducts 3. Alveolar Sacs 4. Alveoli |
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What do Respiratory bronchioles branch from?
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Terminal bronchioles
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What lines the respiratory bronchioles?
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Simple cuboidal epithelium that becomes nonciliated
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Are there Clara cells in the epithelium of the respiratory bronchioles?
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Yes - they become more predominant in the more distal portions of the respiratory bronchioles.
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What are the bronchiole walls interrupted by occasionally?
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Alveoli
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What is a Pulmonary Lobule?
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A terminal bronchiole and the lung tissue it supplies
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What is a Pulmonary Acinus?
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A portion of the lung that is supplied by a respiratory bronchiole
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How are Pulmonary Lobules and Acini related?
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One lobule contains several acini.
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What do the terminal branches of respiratory bronchioles open into?
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Alveolar ducts
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What lines Alveolar ducts?
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Alveoli
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What is present between adjacent alveoli?
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A small septum containing
-smooth muscle -Reticular fibers -Elastic tissue |
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What do alveolar ducts terminate as?
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Alveolar sacs
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Do alveolar sacs contain smooth muscle?
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No
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What type of fibers do alveolar sacs contain?
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Type III collagen and Elastin
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How many alveoli are in each lung?
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150-300 million
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What is the wall of an alveolus called?
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The alveolar septum
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What is the alveolar septum lined with?
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Alveolar epithelium
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What type of cells make up the alveolar epithelium?
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Simple Squamous Type I and Type II Alveolar cells
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What is another name for the simple squamous alveolar cells?
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Pneumocytes
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Which is the predominant type of pneumocyte lining the alveolar surfaces?
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type I - 95% of the surface area is made up of them.
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What joins adjacent Type I pneumocytes?
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Occluding junctions
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What is the function of Type II pneumocytes?
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Production reabsorption and recycling of Pulmonary Surfactant
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What is in the cytoplasm of Type II pneumocytes?
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Lamellar bodies - apical secretory granules.
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Are there fewer Type II pneumocytes in number?
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No they just line less of the alveolar surface area - <5%
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What is a very important function of Type II pneumocytes other than making surfactant?
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They serve as the stem cells for both Type I and Type II pneumocytes.
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What are Alveolar pores?
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Occasional holes in the alveolar septum (walls)
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What important system is found in the alveolar septum?
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Capillaries
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What cells are important for eating dust?
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Macrophages
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What are the 4 components of the blood-gas exchange barrier?
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1. Pulmonary surfactant
2. Type I pneumocyte 3. Fused basement membranes 4. Capillary endothelial cells |
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What is pulmonary surfactant composed of?
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-Phospholipids
-Proteins ABC and D |
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How do the phospholipids and proteins interact as surfactant?
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The lipids float on a layer of proteins.
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What happens to the alveolar cells following heart failure and pulmonary congestion?
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RBCs extravasate into alveoli, get eaten by macrophages, and stain positively for iron.
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What are the macrophages that eat RBCs after heart failure called?
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Heart failure cells
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What are 3 clinical conditions that affect the respiratory passages?
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1. Emphesyma
2. Interstitial Fibrosis 3. Infections |
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What is Emphesyma characterised by?
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Destruction of the alveolar septa leading to enlarged airways but decreased SA for gas exchange.
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What causes the reduced elastic tissue in emphesyma?
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Inhibition of alpha-antitrypsin which normally protects the elastic fibers from degradation.
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Is emphesyma only caused by smoking?
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No it can be caused by liver disease or genetic deficiency of a-antitrypsin.
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What is Interstitial Fibrosis?
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The progressive increase in collagen and elastin production by fibroblasts in the interalveolar septa.
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What results from interstitial fibrosis?
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Gas Exchange is impeded and hypoxia
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What's the common lung infection that reduces the amount of gas exchange due to fluid accumulation within alveoli?
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Pneumonia
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