The brain is also protected by the skull, and the spinal cord is also protected by the vertebrae.
The bodies of the nerve cells lie in the CNS, either in the brain or the spinal cord, and the longer of the cellular processes of these cells, known as axons, extend through the limbs and the flesh of the torso. The large majority of the axons which are commonly called nerves are considered to be PNS. The cell bodies of afferent PNS nerves lie in the dorsal root ganglia.
Autonomic nervous system (ANS) controls smooth and cardiac muscles and organs of digestive, circulatory, excretion and endocrine systems (involuntary actions). ANS consists of two sets of neurons with opposing effects on most body organs.
The endocrine System in humans (overview): The endocrine system is the internal system of the body that deals with chemical communication by means of hormones, the ductless glands that secrete the hormones, and those target cells that respond to hormones. The endocrine system is instrumental in regulating metabolism, growth, development and puberty, and tissue function and also plays a part in determining mood. The endocrine system functions in long term behavior and works in conjunction with the nervous system in regulating internal functions and maintaining homeostasis.
Hormones regulate bodily functions and are specific in their responses. They can only initiate responses in target cells, which are specifically equipped to respond. Each hormone is recognized by those target cells with receptors compatible with their structure. A hormone receptor is a protein within the target cell or built into the plasma membrane. Once a hormone is released, the first step is the specific binding of the chemical signal to a hormone receptor. The receptor molecule enables the target cell to respond to the hormones chemical signal. These responses vary according to target cell and lipid solubility.
The control of hormones can be done by 3 methods:
1. Many hormones are controlled by some form of a negative feedback mechanism. In this type of system, a gland is sensitive to the concentration of a substance that it regulates.
2. Some endocrine glands secrete hormones in response to other hormones.
3. A third method is by direct nervous stimulation.
Integration of endocrine and nervous system: (overlapping of functions)
While the nervous system and endocrine system have their own features, they have a