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8 Cards in this Set
- Front
- Back
First part of respiratory development
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Respiratory diverticulum is small bud coming from foregut (so endoderm). It is a ventral outpocketing.
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Bifurcation of respiratory diverticulum
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Lung buds form from diverticulum.
Top part of diverticulum forms trachea. Lung buds have an inner layer of endoderm, and an outer visceral layer of mesoderm. Lung buds develop into pleuropericardial cavity white top part pinches off to form the trachea, while the rest becomes the esophagus. (from the tracheo-oesophogeal fold). |
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Tracheoesophageal fistula (TE)
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Incomplete separation of esophagus and trachea.
Often accompanied by esophageal atresia (blind pouch, doesn't connect to rest of esophagus). |
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Branching morphogenesis
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Dividing of lung into lobes, smaller units. Also occurs in other organs, like kidneys, mammary glands, salivary glands.
For branching to happen, endoderm and mesoderm interact. Fgf10 (same thing that extended limb buds) works alongside Shh (sonic hedhehog) to extend branching. |
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Structure of branching
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Tertiary bronchi: 10 in the right lung, 8 or 9 in the left lung.
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Last part of lung development
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Cuboidal epithelium of the terminal sacs (primordial alveoli) thins, making lungs more vascular.
From 24 weeks to birth, contact between epithelial cells of the lung and endothelium of the capillaries provides enough gas exchange in case of premature birth. Number of alveoli continues to increase during childhood. Only 1/6th present in babies (of total adult amount). |
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Respiratory Distress Syndrome
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By 6 months in utero, alveoli mature enough for gas exchange, but surfactant production insufficient. This is major cuase of RDS (aka hyaline membrane disease).
All babies born before 28 weeks get it. Surfactant replacement therapy heals (through tube). |
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Surfactant
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Reduces surface tension and prevents alveolar collapse.
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