Anatomy Practice Exam

What triggers a cell response for protein hormones?

1. Direct DNA manipulation

2. Surface receptor binding

3. Intracellular signal transmission

4. Hormonal feedback loops

The correct answer is: Surface receptor binding

Protein hormones are hydrophilic and typically unable to pass through the lipid bilayer of the cell membrane. Instead, they exert their effects by binding to specific receptors located on the surface of target cells. This binding activates those receptors, triggering a cascade of intracellular events that lead to a cellular response, such as alterations in enzyme activity or gene expression. This mechanism of action highlights the importance of surface receptor binding in initiating the response to protein hormones. It is through this interaction that the hormone can convey its signal to the inside of the cell, leading to the desired physiological effect. The other options do not directly address how protein hormones trigger cellular responses, as they involve either direct manipulation of DNA, processes within the cell post-binding, or wider regulatory mechanisms rather than the initial activation step.