The Nervous System

R.ThorneB2

What is that Nervous thing all about?

The Nervous system is what keeps your body doing what it needs to do. It regulates the body’s autonomic functions such as breathing, reflexive actions, and somatic functions like walking. The central nervous system makes it’s decisions based on stored sensory input from past experiences and sensory input from the peripheral nervous system and it’s sensory receptors throughout the body.

             

What does it consist of?

They include:

Astrocytes- abundant star-shaped, account for nearly half of the neural tissue. They form the barrier for the neutrons.

Microglia- spiderlike phagocytes that dispose of dead tissue.

Ependymal- line the cavities of the brain and spinal cord and circulate the cerebrospinal fluid.

Oligodendrocytes- wrap their flat extensions around the nerve fibers, producing fatty insulating coverings called myelin sheaths.

PNS

Schwann cells- form myelin sheaths

Satellite cells- protective cushioning cells

The nerves are made of supporting cells called Neuroglia or nerve glue, which consists of many types of cells lumped together to protect and nurture the delicate neurons that carry sensory input.

ANATOMY AND PHYSIOLOGY

• Neurons or nerve cells are used to transmit nerve impulses. They consists of a cellbody surrounded by a rough ER, called Nissl and neurofibrils. It has armlike fibers that either convey incoming messages to the cell, dendrites or away from it, axons. Each neuron has only one axon, which is covered with axon terminals which contain hundreds of tiny vesicles that contain neurotransmitters.

• Neurons have two major functional properties: irritability and conductivity. Initially a neuron is in a polarized or positive state in which the inside is more negative then the outside. When an electrical message must be sent an influx of sodium is used to depolarize the neuron, changing it to a negative charge on the outside and postive inside. This situation is called graded potential. The electrical message sent is called and action potential. Immediately afterwards the sodium is cut off from the cell and it is diffused with potassium. During repolarization the cell returns to its polarized state and is ready for the next impulse.

CNS, PNS, SNS, ANS, Sympathetic,

ParasympatheticCNS-Central Nervous System- consists of the brain and spinal cord and acts as a

command center for the nervous system. It interprets incoming sensory input and issues instructions.

PNS-Peripheral Nervous System- all parts outside the CNS, consists mainly of nerves that branch out from the brain and spinal cord, their function is to carry electrical impulses to and from the brain.

SNS- Somatic Nervous System- allows voluntary control of the skeletal muscles.

ANS- Autonomic Nervous System- regulates all the involuntary muscle movements. It consists of the sympathetic and parasympathetic, which each bring about the opposite of the other. While one stimulates, the other inhibits.

A Disturbance in the HeadJoubert Syndrome- affects the body’s

balance and coordination.Alzheimer’s Disease- common symptoms

include memory loss, irritability, confusion, mood swings, and language breakdown.

Pain Disorder- involves chronic pain in one or more areas.

Cerebral Palsy- the diverse affects include: body deformation, low muscle tone, tremors, increased muscle tone, involuntary motions.

Psych Out!Alcohol- impairs judgment, speech, distorts vision, and

can lead to brain damage as well.Ecstasy- extended use can cause difficulty distinguishing reality from

hallucinations, impairs memory and can cause paranoia, anxiety, and confusion.

LSD- causes paranoia, confusion, anxiety, and panic attacks, also similar to Ecstasy in that users blur reality.

Heroin- brain cells become completely dependent on the drug. The initial pleasure of the drug is continually phased out as the body is accustomed to the increased endorphins.

Here be some Hyperlinks

http://en.wikipedia.org/wiki/Nervous_system

http://www.brainsource.com/brain_on_drugs.htm

http://en.wikipedia.org/wiki/Neurological_disorders