As you know the nine centers represent psychological elements (such as emotions, for example) but you probably aren't as aware that they are deeply rooted in the physical body. This distinction between psychology and physical body is of course irrelevant since the two are inseparable. But scientifically, especially in western science, we are very ignorant as to how the physical and psychological meet, let alone the spiritual. Human Design clearly shows the connection.

Here is a chart of the endocrine system in females and males. Can you connect the Centers with the corresponding endocrine gland?

Biologically the majority of centers belong to the endocrine and nervous system or are closely connected to them. The nervous and endocrine systems act together to regulate physiology. The endocrine system is a collection of glands scattered throughout the body that secrete chemical messages in the form of hormones. These signals are passed through the blood to arrive at a target organ, which has cells possessing the appropriate receptor.

In addition to the classical endocrine organs, many other cells in the body secrete hormones. Myocytes in the atria of the heart and scattered epithelial cells in the stomach and small intestine are examples of what is sometimes called the "diffuse" endocrine system. If the term hormone is defined broadly to include all secreted chemical messengers, then virtually all cells can be considered part of the endocrine system, which means that the physical parts of the body associated with the centers are deeply influencing every part of our body through the constant relay of messages.

Key Points:

• All bodily events are influenced by the endocrine milieu:
  There are no cell types, organs or processes that are not influenced - often profoundly - by hormone signaling.
• All "large" physiologic effects are mediated by multiple hormones acting in concert:
  Normal growth from birth to adulthood, for example, is surely dependent on growth hormone, but thyroid hormones, insulin-like growth factor-1, glucocorticoids and several other hormones are also critically involved in this process.
• There are many hormones known and little doubt that others remain to be discovered.

Biology - Keep it to yourself

Just because the head center has a relationship with the Pineal Gland does not mean you need to tell people that. It is probably a good idea you don't go into the biology when you are showing somebody their chart, regardless of the temptation to impress them with how much cool (and basically useless) info you have crammed in your brain.

Knowing the biological relationship has very little impact on whether a person will live their strategy and honor their authority, which is the only important thing. In fact, if you go into great detail about the biology of the centers, it will probably distract and confuse them. Don't do it. KISS - keep it simple.

The goal in this course of showing you the biology is just to give you an idea of the background behind centers so that you understand how they concretely connect to the body. The biology gives useful insights into the psychological characteristics of the centers, which can be very useful when looking at a chart.