Nervous
Functions:
The brain and spinal cord make up the central nervous system. The
organs, muscles, and other parts of the body are all connected to the central
nervous system by an intricate network of nerves stretched throughout the
body. Each of these nerves is a bundle of thread-like nerve cells, bound
together within a sheath of tissue. Messages travel only one way along our
nerves, and the same nerve cell doesn�t carry messages both ways at once.
The nerves that connect the central nervous system to the different parts of
the body make up the perciphal nervous system. There are two types of
periphal nerve cells: sensory nerves, and motor nerves. The sensory nerves
are connected to the sense organs. The motor nerves are connected to all of
the other parts of the body. Sensory nerves let the central nervous system
know what is going on in and around the body. Motor nerves tell the
muscles to move, the glands to secrete chemicals, the lungs to breathe, the
heart to pump, and the stomach to churn. Some nerves are under conscious
control, and others are reflex actions. Some messages that are called reflex
actions are blinking your eye, or ducking from a rock flying at you, or pulling
your hand away after touching a very hot pot. The muscles that are under
conscious control are the ones like wiggling your finger, or tapping your toe.
There are also nerves called automatic nerves. These are often things that we
are not aware of. They coordinate the activities of the heart, lungs, stomach,
intestines, and various other organs within our bodies.
Major parts and organs:
The major parts and organs of the nervous system are the brain, the
hind brain, the pons, the medulla oblongata, the cerebellum, the
midbrain, the forebrain, the cerebrum, and the spinal cord. The brain is
the central controlling and coordinating organ of the nervous system. It
controls everything you do, feel, and think. It receives information from your
body, processes it, and sends messages to your muscles and other parts of
your body, telling it how to act. It�s the most complex part of the nervous
system. The brain is made up of three parts: the hind brain, the midbrain,
and the forebrain. The hind brain, which forms a swelling at the head end of
the spinal cord, consists of the pons, medulla oblongata, and the cerebellum.
The pons forms a bridge between the midbrain and medulla oblongata. The
medulla oblongata controls some automatic functions such as breathing,
swallowing, heartbeat, and digestion. The cerebellum helps to control
balance and coordinate movements. The midbrain is the most highly
developed part of the brain in primitive vertebrates. It contains centers for
crude forms of seeing and hearing. The forebrain has one major part in it,
called the cerebrum. The cerebrum receives and processes information
both from the sense organs and from the more primitive parts of the brain. It
is involved in thought, reasoning, and decision making. The spinal cord is
connected to the brain, and together they make up the central nervous
system. Together, they control all of your actions.
Interactions with other systems:
The nervous system interacts with many other systems. Three of them
are the Muscular, Skeletal, and Respiratory systems. Nerves are attached
to every muscle in the Muscular system. Nerves send messages to the
muscles, instructing them to move. Your spinal cord and many other nerves
are protected by the Skeletal system. Your Respiratory system is partly
controlled by the Nervous system. When your body�s need for oxygen
increases, the nervous system steps up your breathing.
Diseases:
Some diseases of the nervous system are multiple sclerosis,
epilepsy, Parkinson�s. Multiple sclerosis occurs in the central nervous
system, in which myelin is gradually destroyed, and multiple lesions develop
in the brain and spinal cord. The cause is unknown, and symptoms vary.
The main form of therapy is corticosteroids. Epilepsy is a chronic brain
disorder characterized by repeated convulsions or seizures. Anticonvulsants
are used to control the seizures. Parkinson�s is a slowly progressive
disabling ailment marked by tremor and increasing stiffness of the muscles.
Drugs such as Benztropine are used in the early stages of Parkinson�s disease. The disease
affects more men that women, and is most likely to develop at age thirty-five.
It occurs in all parts of the world, and about 200,000 cases are reported in
the United States annually.