Two main regulatory system

1. Regulatory systems do communicate within the cells and between groups of cells or tissues.

2. In human, there are two main regulatory systems: central nervous system and endocrine system.

3. The hormonal elements are a number of agents involved in these regulatory systems.

4. They control and regulate cellular activity.

5. The nervous system exerts point-to-point control through nerves, similar to sending messages by conventional telephone. Nervous control is electrical in nature and fast.

6. The Endocrine System broadcasts its hormonal messages to essentially all cells by secretion into blood and extra cellular fluid. Like a radio broadcast, it requires a receiver to get the message - in the case of endocrine messages, cells must bear a receptor for the hormone being broadcast in order to respond.

7. As will be repeatedly demonstrated, the nervous and endocrine systems often act together to regulate physiology. Indeed, some neurons function as endocrine cells.