HUMAN ANATOMY...Both cystic fibrosis and chronic bronchitis cause cells of the r

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HUMAN ANATOMY...Both cystic fibrosis and chronic bronchitis cause cells of the respiratory system to hypersecrete mucus. The excessive mucus makes gas exchange more difficult and allows bacteria to thrive, often causing secondary infections. What type(s) of cells in the lungs are responsible for extra mucus production? Select all that apply.....

Both cystic fibrosis and chronic bronchitis cause cells of the respiratory system to hypersecrete mucus. The excessive mucus makes gas exchange more difficult and allows bacteria to thrive, often causing secondary infections. What type(s) of cells in the lungs are responsible for extra mucus production? Select all that apply O Mucous cells O Ciliated squamous cells O Ciliated columnar cells O Serous cells Submit My Answers Give Up

Explanation / Answer

Ciliated squamous and columnar cells.The induction of a chronic mucus-producing airway epithelium requires 2 signals. Signal 1 activates the EGFR on ciliated cells and induces EGFR phosphorylation and activation of PI3K/Akt. This pathway leads to inhibition of ciliated cell apoptosis. Ciliated cells that survive can respond to signal 2: IL-13 binding to its receptor. Upon IL-13 receptor (IL-13R) activation and STAT6 signaling, ciliated cells begin to produce mucins (including those encoded by MUC5AC), which are contained within mucous secretions, and lose their ciliated cell surface, taking on features of mucus-producing goblet cells. It also appears that other epithelial cells, such as Clara cells, can differentiate into goblet cells. Thus, the airway epithelium is driven to become a mucus-producing organ, presumably to enhance host defense. In some diseases, such as asthma, this response may be misdirected.

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