NURS 6501: MIDTERM EXAM: Please contact Your Favorite Professor for help with   NURS 6501: Midterm Exam or any other assignment. Email: professorrobertphd@gmail.com   Which type of cell adaptation occurs when normal columnar ciliated epithelial cells of the bronchial lining have been replaced by stratified squamous epithelial cells? Group of answer choices

• Anaplasia
• Hyperplasia
• Metaplasia
• Dysplasia

  The correct answer is Metaplasia. Explanation: Metaplasia is the process in which one type of differentiated cell is replaced by another type of cell that is not normally present in that tissue. In the case described, the normal columnar ciliated epithelial cells of the bronchial lining are replaced by stratified squamous epithelial cells. This change is typically a response to chronic irritation or injury, such as from smoking or chronic respiratory infections. It allows the tissue to better withstand the irritation, but it can also impair the normal function of the respiratory epithelium, such as mucus clearance. Why the other options are incorrect:

• Anaplasia: This refers to a loss of cellular differentiation and structure, usually seen in cancerous cells. Anaplasia is associated with malignant transformation and is not simply a response to irritation or stress.
• Hyperplasia: This is an increase in the number of cells in a tissue, often in response to a stimulus (such as growth factors or hormonal changes). However, in hyperplasia, the cells remain of the same type, which is different from metaplasia where the type of cell changes.
• Dysplasia: This refers to abnormal development or growth of cells, often characterized by changes in size, shape, and organization. While dysplasia can be a precancerous condition, it is different from metaplasia in that the cells show abnormal features rather than just a change in cell type.

Thus, the replacement of columnar ciliated epithelial cells with stratified squamous epithelial cells is a classic example of metaplasia, which is an adaptive response to chronic irritation.