A Mode of Communication

Like players on a team, the individual cells of an animal's body must communicate with one another, to ensure the proper functioning of the whole. Hundreds of decisions must be made and communicated throughout the body every minute. Methods of communication between cells fall into four broad categories:

• direct
  
• synaptic
  
• paracrine
  
• endocrine
  

Function

The endocrine system consists of the endocrine hormones and the glands that produce them.

Pineal Gland

---

References

Audesirk, T., Audesirk, G. and Byers, B. (2011). Biology. 9th ed. Boston, Mass.: Benjamin Cummings.