*~ Your Brain.......*~
 

[CENTER][FONT=Times New Roman][SIZE=5][COLOR=darkslateblue][B][I][U]Human Brain Structure and their Functions[/U][/I][/B] [/COLOR][/SIZE][/FONT][/CENTER]

[COLOR=darkslateblue]• Cerebrum
• Cerebellum
• Limbic System
• Brain Stem[/COLOR]

The nervous system is your body's decision and communication center[COLOR=purple].[U]The central nervous system (CNS)[/U][/COLOR] is made of the brain and the spinal cord and
the [COLOR=purple][U]peripheral nervous system (PNS)[/U][/COLOR] is made of nerves.

Together they control every part of your daily life, from breathing and blinking to helping you memorize facts for a test. Nerves reach from your brain to your face, ears, eyes, nose, and spinal cord... and from the spinal cord to the rest of your body. Sensory nerves gather information from the environment, send that info to the spinal cord, which then speed the message to the brain. The brain then makes sense of that message and fires off a response.

[I][U]Motor neurons [/U]deliver the instructions from the brain to the rest of your body[/I].

[I]The [U]spinal cord[/U], made of a bundle of nerves running up and down the spine, is similar to a superhighway, speeding messages to and from the brain at every second. [/I]

The brain is made of [I]three[/I] main parts:
1)the forebrain,
2)midbrain, and
3)hindbrain.

[COLOR=indigo][U]The forebrain[/U][/COLOR] consists of the [I]cerebrum, thalamus, and hypothalamus [/I](part of the limbic system). The [U]midbrain[/U] consists of the [I]tectum and tegmentum[/I]. The [U]hindbrain[/U] is made of the [I]cerebellum, pons and medulla[/I].
Often the [I]midbrain, pons, and medulla [/I]are referred to together as the [U]brainstem[/U].

[COLOR=darkorchid][SIZE=4][FONT=Palatino Linotype][B][U]The Cerebrum[/U]: [/B][/FONT][/SIZE][/COLOR]
The cerebrum or cortex is the [I]largest part[/I] of the human brain, associated with higher brain function such as thought and action. The cerebral cortex is divided into four sections, called "lobes":

1)the frontal lobe,
2)parietal lobe,
3)occipital lobe, and
4)temporal lobe.

Here is a visual representation of the cortex:

[IMG]http://usera.imagecave.com/eram/cerebrum.gif[/IMG]

[I]What do each of these lobes do? [/I]

• [COLOR=indigo][U]Frontal Lobe- [/U][/COLOR]associated with reasoning, planning, parts of speech, movement, emotions, and problem solving
• [COLOR=indigo][U]Parietal Lobe-[/U][/COLOR] associated with movement, orientation, recognition, perception of stimuli
• [COLOR=indigo][U]Occipital Lobe- [/U][/COLOR]associated with visual processing
• [COLOR=indigo][U]Temporal Lobe- [/U][/COLOR]associated with perception and recognition of auditory stimuli, memory, and speech

[U]Note that[/U] the cerebral cortex is highly wrinkled. Essentially this makes the brain [I]more efficient[/I], because it can increase the surface area of the brain and the amount of neurons within it.

A deep furrow divides the [I]cerebrum into two halves[/I], known as the left and right hemispheres. The two hemispheres look mostly symmetrical yet it has been shown that each side functions slightly different than the other. Sometimes the [U]right hemisphere[/U] is [I]associated with creativity[/I] and the [U]left hemispheres [/U]is [I]associated with logic abilities[/I].
The [U]corpus callosum[/U] is a [I]bundle of axons which connects these two hemispheres. [/I]
[U]Nerve cells[/U] make up the gray surface of the cerebrum which is a little thicker than your thumb. [U]White nerve fibers [/U]underneath [I]carry signals between the nerve cells and other parts of the brain and body[/I].

The [COLOR=darkgreen][U]neocortex[/U[/U][/COLOR][U]] occupies the [I]bulk of the cerebrum[/I]. This is a six-[I]layered structure of the cerebral cortex [/I]which is only found in mammals. It is thought that the neocortex is a recently evolved structure, and is associated with "higher" information processing by more fully evolved animals (such as humans, primates, dolphins, etc). [/U]

[u][COLOR=darkorchid][SIZE=4][FONT=Palatino Linotype][B][U]The Cerebellum:[/U] [/B][/FONT][/SIZE][/COLOR]
The cerebellum, or [COLOR=blue][I]"little brain", [/I][/COLOR]is similar to the cerebrum in that it has two hemispheres and has a highly folded surface or cortex. This structure is associated with regulation and coordination of movement, posture, and balance.
The cerebellum is assumed to be much older than the cerebrum, evolutionarily.
[I][COLOR=teal]What do I mean by this? [/COLOR][/I]
In other words, animals which scientists assume to have evolved prior to humans, for example reptiles, do have developed cerebellums. [I]However, reptiles do not have neocortex [/I]

[COLOR=darkorchid][SIZE=4][FONT=Palatino Linotype][B][U]Limbic System:[/U] [/B][/FONT][/SIZE][/COLOR]
The limbic system, often referred to as the [I][COLOR=blue]"Emotional Brain", [/COLOR][/I]is found buried within the cerebrum. Like the cerebellum, evolutionarily the structure is rather old.
This system contains the thalamus, hypothalamus, amygdala, and hippocampus. Here is a visual representation of this system, from a midsagittal view of the human brain:

[IMG]http://usera.imagecave.com/eram/limbicsystem.gif[/IMG]

• Thalamus
• Hypothalamus
• Amygdala
• Hippocampus


[COLOR=darkorchid][SIZE=4][FONT=Palatino Linotype][B][U]Brain Stem:[/U] [/B][/FONT][/SIZE][/COLOR]
Underneath the [I]limbic system [/I]is the brain stem. This structure is responsible for basic vital life functions such as [I]breathing, heartbeat, and blood pressure[/I]. Scientists say that this is the [I]"simplest" [/I]part of human brains because animals' entire brains, such as reptiles (who appear early on the evolutionary scale) resemble our brain stem.
The brain stem is made of the midbrain, pons, and medulla.
• Midbrain
• Pons
• Medulla