Nervous Systems the Central Nervous

¶ … Nervous Systems

The central nervous system is composed of the spinal cord and the brain. Along with these specific structures, the central nervous system also encompasses the neural tissue, blood vessels, and the connective tissue that surround these structures for protection (Martini, Nath, & Bartholomew, 375). It is the job of the central nervous system to integrate, process, and coordinate sensory data into motor commands. The central nervous system receives the information that the body needs in order to execute a motor movement, and then signals are sent out commanding the body to perform these specific movements (Martini, Nath, & Bartholomew, 375). The sensory data received can be in relation to conditions on the outside or the inside of the body. The control of muscles is regulated by the central nervous system in order to react to situations where the human body can be in danger. For example, if a person steps on a tack that hurts the foot, a person's natural reflex would be to remove the foot immediately from the source of pain. It is the central nervous system that sends the signals to the brain that make the body move the foot away from the tack.

The central nervous system is made up the higher functioning structures of the brain and the spinal cord. The brain structures can be further broken down to include the brain stem, such as the medulla oblongata, pons, cerebellum and the mesencephalon, diencephalon, and the cerebrum (Martini, Nath, & Bartholomew, 456). These are all structures that allow humans to attain their unique features. They regulate behavior, emotions, and feelings. These structures are constantly being innervated by nerve cells that come from the spinal cord (Martini, Nath, & Bartholomew, 452). Both the spinal cord and the brain are covered by meninges that assist in the process of sensory processing and in the protection of the brain and spinal cord. These meninges are the dura mater, the arachnoid mater, and the pia mater. The layers provide the blood and the nutrients for the central nervous system. They are also responsible for the creation of the cerebral spinal fluid which is critical to the survival of the brain and the spinal cord (Martini, Nath, & Bartholomew, 420 & 454).

The peripheral nervous system is composed of the neural tissue outside of the central nervous system. The purpose of the peripheral nervous system is to deliver the sensory information to the central nervous system, and from the central nervous system (Martini, Nath, & Bartholomew, 375). The peripheral nervous system sends the motor commands directly to the peripheral tissues and other systems. The nerve fibers that compose the peripheral nervous system carry these signals which will then lead to an actual action on the part of the body (Martini, Nath, & Bartholomew, 375). There are two divisions: the afferent division and the efferent division. The afferent division of the peripheral nervous system brings signals or sensory information to the central nervous system from the receptors that are located at the target organs or tissues. Any changes in the environment that are noticed by these peripheral structures are then signaled to the central nervous system for further processing and understanding (Martini, Nath, & Bartholomew, 379). The efferent division of the peripheral nervous system carries out the motor commands that are sent from the central nervous system. These commands or signals are then sent directly through the nerve fibers of the peripheral nervous system to the target organs where they will then be signaled to perform the desired action (Martini, Nath, & Bartholomew, 380).

The peripheral nervous system can be further broken down as being a part of the somatic nervous system and the autonomic nervous system (Martini, Nath, & Bartholomew, 375). The efferent division works in both of these systems as they are only possible through the motor commands sent from the central nervous system. The somatic nervous system controls voluntary movement. The signals innervate skeletal muscles that a person can consciously control (Martini, Nath, & Bartholomew, 376). A reflex is also controlled by the peripheral nervous system and the somatic nervous system. When an individual's hand accidentally touches a hot surface, the first instinct is to withdraw the hand; this is possible because of the somatic and peripheral nervous system. The autonomic nervous system is what is commonly called the "fight or flight" system. It is made up of the sympathetic and parasympathetic divisions and are not a part of an individual's control (Martini, Nath, & Bartholomew, 375). These involuntary movements include the regulation of the smooth muscle tissue that surrounds the majority of a person's organ systems and blood vessels, the cardiac muscle around the heart, and secretions from glands (Martini, Nath, & Bartholomew, 375).