neuronerd

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DIVISIONS OF THE NERVOUS SYSTEM IMAGES

TELENCEPHALON:

DIENCEPHALON

MESENCEPHALON:

METENCEPHALON

MYELENCEPHALON

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DIVISIONS OF THE NERVOUS STYSTEM 1

NEUROANATOMY: structure of nervous system

Nervous system is divided into the peripheral Nervous system and central nervous system.

Central nervous system: divided into the brain and spine. some might say it might include the retinas as well.

Peripheral nervous system: divided into 2 major parts

somatic system and autonomic nervous system.

Somatic Nervous System

“The somatic nervous system consists of peripheral nerve fibers that send sensory information to the central nervous system AND motor nerve fibers that project to skeletal muscle.”

Autonomic Nervous System

divided into three parts

the sympathetic nervous system,

the parasympathetic nervous system

and the enteric nervous system.

The autonomic nervous system controls smooth muscle of the viscera (internal organs) and glands.

“This picture shows the general organization of the autonomic nervous system. The preganglionic neuron is located in either the brain or the spinal cord. This preganglionic neuron projects to an autonomic ganglion.

The postganglionic neuron then projects to the target organ. Notice that the somatic nervous system has only one neuron between the central nervous system and the target organ while the autonomic nervous system uses two neurons”

The enteric nervous system

is a third division of the autonomic nervous system that is practically unheard of since people do not speak of it often but the enteric nervous system is a meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, gall bladder).

This table shows how the nervous system is divided

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IMPORTANT BASICS

NUERON DEFINED: A neuron is a nerve cell in the brain, the brain is made up of about 86 billion of these little things.

They are similar to other cells in the aspect of them being

1. surrounded by a membrane

2. having a nucleus that contains genes

3. having a cytoplasm, mitochondria and other "organelles".

They differ due to them being

1. having specialized projections called dendrites and axons.

Dendrites bring information to the cell body and

axons take information away from the cell body.

2. being able to communicate with each other through an electrochemical process.

3. having a form of special connections called "synapses" and produce special chemicals called "neurotransmitters" that are released at the synapse.

MORE FUN INFO!

there are 1 quadrillion synapses in the human brain.

the brain weighs about 3 pounds.

is 2% of body weight (though this statistic can vary based on what scientist you ask.)

spinal cord is 45 cm long in men, 43 in women. It weighs about 35 g.

transmission throughout the NERVOUS SYSTEM can be as slow as .5 meters per second or as fast as 120 METERS PER SECOND!