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Chemical Signaling and Endocrine System Basics

Chemical Signaling Pathways & Introduction to the Endocrine System

Advanced Second Messenger Pathways

Phospholipase C Pathway

  • Enzyme: Phospholipase C.

  • Action: Cleaves membrane phospholipids into two distinct second messengers:

    • Inositol Triphosphate (IP_3): Triggers specific calcium (Ca^{2+}) channels to open within the cell. This leads to a rapid increase in cytoplasmic calcium levels by releasing calcium from intracellular stores.

    • Diacylglycerol (DAG): Increases cytoplasmic calcium by promoting calcium influx from outside the cell.

  • Result: Both IP_3 and DAG cooperate to cause a significant flood of calcium into the cytoplasm.

  • Calcium (Ca^{2+}): Functions as another crucial second messenger. This illustrates that multiple distinct molecules can act as second messengers, rather than a sequential