Embryology and the Nervous System

by Georgianna Donadio, MSc, DC, PhD

To begin understanding the "whole picture of health"* one must begin with the moment of conception and the first system that develops within the body.

As the goal of this blog is to facilitate a demystified understanding of how everything is connected to everything else in the human mind/body experience, understanding the central nervous system and its origins in embryological development, is paramount to appreciate the brilliance and biological organization of being human.

Conception occurs when particular hormonal, biochemical and physical conditions are present. Human sperm and egg, proper vaginal PH, oxytocin to facilitate implantation and a healthy host uterus are all essential components. Also at play is the magical presence of "phermones" - powerful chemical/hormonal secretions which set the stage for attraction and healthy conception. When these elements collude, a fertilized egg is embedded in the uterus where rapid growth and cellular differentiation takes place to form the smallest of humans - the fetus.

Variations of fetal growth is effected by many influences. The health and nutrition of the
mother, genetic coding, chemical imput from the environment, stress, exertion, emotions, infection, the health of the sperm - all express their presence during early development.
The selective process of how one of billions of sperm succeeds in fertilizing the egg, soon to be fetus, is the miracle of conception. Even with our sophisticated understanding of the science of birth and conception, the dependably of how it succeeds, that it succeed, and has succeeded billions of times over thousands of years is truly awesome.

Within the first few days of embryonic development, after the primary group of (blastula) cells flatten and fold, like a piece of paper forming a tubular roll, little buds which are rudimentary vertebre and spinal nerves begin to develop. From the moment the "body" forms, the nervous system appears to facilitate and innervate function and movement as well as control every cell in the body.

Just how powerful and critical the human nervous system is cannot be overstated. When synapse is gone from the body, it can no longer function. Neurological synapse = life.

The brain is the synapse generator and the CEO of the nervous system. A simplistic look at the human nervous system:

There are two main systems - central and peripheral.

Central Nervous System -

The central nervous system is made up of the brain and spinal cord and is located in the center of the body.

1. The spinal cord is a column of tissue about 18 inches long, the thickness of a human finger. It resides in the spinal canal, inside the bony structure of the spinal column or "backbone". The spinal cord has two primary functions. One is to respond to body stimulation by producing spinal reflexes. These are local responses and can occur even after a spinal cord is severed from the brain. For example, if you pinch the bottom of a frog, it will jump even if the brain and spinal cord are damaged. A second function serves as the physiological highway for the brain by conducting spinal nerve, technically called "supraspinal activity", to and from all cells, and to and from all parts of the body to the brain.

2. The human brain is the centerpiece of the central nervous system - the master organ of the body because without it - as in cases of brain death - the conscious human is no more. The brain controls almost all informational discernment as well as adaptation to the world at large. Through its control of the peripheral nervous system, it regulates lower, involuntary functions of the body, such as heart rate, respiration, blood pressure and digestion. The brain also controls higher order functions, such as thinking, analysis, integration and evaluation of information that humans can respond effectively to in the world it inhibits.

Peripheral Nervous System

The peripheral nervous system connects functions of the central nervous system brain and spinal cord to the outer boundaries of the body. It has two main divisions: somatic nervous system and autonomic nervous system.

1. The somatic nervous system - which means pertaining to the body - consists of 12 pairs of cranial nerves, which control functions in head, facial and some digestive functions and of 31 pairs of spinal nerves, which control functions in the rest of the body, including skeletal muscles. The somatic nervous system receives information from the sensory motor components: eyes, ears, nose, mouth, touch and responds to that information, expressing it through the body's muscular function.

* This is an important piece of information to tuck in your hat. When we discuss the mind/body connection, the role of the somatic nervous system begins to take on a paramont meaning

2. While the somatic nervous system controls organs, mostly muscles, under voluntary control, the autonomic nervous system regulates individual organs which are made up of smooth muscle and which are not generally under voluntary control. These are "automatic" or "vegetable state" organics. This is why a body, deep in coma, will continue its organ functions even though the conscious state is absent. The heart, kidneys, blood vessels, liver and so forth can function "automatically" thru the autonomic nervous system.

The autonomic nervous system has two main branches that control these "automatic functions".
The "sympathetic" nervous system, which enables the body to react in the "fight or flight" response and the "parasympathetic" nervous system, concerned with maintaining homeostasis or balance in the body. Odd names for the two aspects of the "automatic" nervous system that can be viewed as the ever viligant protector of the human body, working 24/7 to preserve and protect.

Understanding this basic organization is the first step to connecting all the dots and create "the whole picture of health."*

Our next discussion is on brain function and behavior and what emotions really are.

With all good wishes,
G
© by NIWH 2010 all rights reserved

* The Whole Picture of Health" is a registered trademark of
the National Institute of Whole Health