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The Respiratory Tract - Coggle Diagram
The Respiratory Tract
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Structures
Trachea
C-shaped regions of cartilage and trachealis muscle makes up the rigid structure of the trachea.
The epithelium contains goblet cells which secrete mucus.
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Bronchi
Lined by a mucous membrane, has a connective tissue layer which contains spiral bands of bronchial smooth muscle. Also has irregular plates of bronchial cartilage.
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LP= Lamina Propria - The lamina propria is a layer of loose connective tissue directly localized underneath the epithelium and populated with a variety of specialized immune cells including T lymphocytes, IgA-secreting B lymphocytes, and antigen-presenting cells.
SM= Submucosa - The submucosa is a thick layer of loose connective tissue that surrounds the mucosa. This layer also contains blood vessels, lymphatic vessels, and nerves. Glands may be embedded in this layer.
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Bronchus
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Bronchi are histologically similar to the trachea. They are lined by ciliated, pseudostratified columnar epithelium (respiratory epithelium) and interspersed with goblet cells. The walls of bronchi are also supported by cartilage and smooth muscle.
The primary function of goblet cells is to secrete mucin and create a protective mucus layer. Goblet cells are also thought to be involved with immunoregulation.
Cilia move microbes and debris up and out of the airways. Scattered throughout the cilia are goblet cells that secrete mucus which helps protect the lining of the bronchus and trap microorganisms.
Basal cells provide an attachment site for ciliated and goblet cells to the basal lamina. They also respond to injury and act in oxidant defense of the airway epithelium and transepithelial water movement.
In the airway, the epithelial basement membrane provides both the substrate for the epithelium and the boundary that strictly separates the epithelial and mesenchymal compartments
While in the capillaries, blood gives off carbon dioxide through the capillary wall into the alveoli and takes up oxygen from air in the alveoli.
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Bronchioles
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Differences to bronchi
While the bronchi constitute C-shaped cartilages, the bronchioles lack cartilaginous support.
bronchi have a larger diameter compared to bronchioles as they're located before the respiratory passageway.
The bronchi carry air into your lungs. At the end of the bronchi, the bronchioles carry air to small sacs in your lungs called alveoli.
Bronchi have psuedostratisfied ciliated columnar epitheliums, bronchioles only have cuboidal epithelium
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Differences-folded, no cartilage, more smooth muscle, reduced cross sectional area.
Similarities-squamous ciliated epithelium, goblet cells
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Alveoli
Structure
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Dimensions- diameter changes with inflation & deflation of the lung, varies with size of animal
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Fibre ‘skeleton'- connective tissue cells & fibres form alveolar interstitium. This includes a ‘skeleton’ of collagen fibrils and elastic fibres.
Alveolar wall:
Traveling from the alveoli to capillary blood, gases must pass through alveolar surfactant, alveolar epithelium, basement membrane, and capillary endothelium.
Pulmonary surfactant is produced by alveolar type II cells and is required for lung function after birth
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