Final answer:
The extrinsic pathway of apoptosis is triggered by external signaling, whereas the intrinsic pathway is triggered by internal damage to the cell.
Step-by-step explanation:
The extrinsic pathway of apoptosis occurs following binding of death receptors on the outside of the plasma membrane of a cell, whereas the intrinsic pathway is triggered by signaling molecules produced within the cell.
The extrinsic pathway is initiated by external signaling, such as trauma or contact with the extracellular matrix, which activates death receptors on the cell surface. These death receptors then initiate a signaling cascade within the cell, leading to apoptosis.
On the other hand, the intrinsic pathway is triggered by internal damage to the cell, such as DNA damage or cellular stress. This triggers the release of signaling molecules from the mitochondria, which in turn activates intracellular signaling pathways leading to apoptosis.