What is the Nervous System??
Tasting, smelling, seeing, hearing, thinking, dreaming, breathing, heart beating, moving, running, sleeping, laughing, singing, remembering, feeling pain or pleasure, painting, writing...you couldn't do any of these things without your central nervous system!
What is the nervous system?
Made up of your brain, your spinal cord, and an enormous network of nerves that thread throughout your body, it's the control center for your entire body. Your brain uses information it receives from your nerves to coordinate all of your actions and reactions. Without it, you couldn't exist!
What are nerves?
They're the thin threads of nerve cells, called neurons that run throughout your body. Bundled together, they carry messages back and forth just the way that telephone wires do. Sensory nerves send messages to the brain and generally connect to the brain through the spinal cord inside your backbone. Motor nerves carry messages back from the brain to all the muscles and glands in your body.
So how do they they pass along messages?
Through the marvels of chemistry and a kind of electricity! Neurons are thin. Some are very small, and some can be three feet long! All are shaped somewhat like flat stars which have, to varying degrees, been pulled at each end so that they have long fingers. The fingers of one neuron almost reach to the next neuron.
When a neuron is stimulated -- by heat, cold, touch, sound vibrations or some other message -- it begins to actually generate a tiny electrical pulse. This electricity and chemical change travels the full length of the neuron. But when it gets to the end of finger-like points at the end of the neuron, it needs help getting across to the next extended finger. That's where chemicals come in. The electrical pulse in the cells triggers the release of chemicals that carry the pulse to the next cell. And so on and so on and so on.
Remind you of anything?
How about a cool relay of dominoes in which one standing domino falls and trips the next and the next and the next.
THE BRAIN:
The brain is the most complex organ in the body. It is the organ that allows us to think, have emotions, move, and even dream. Given this complexity, it should not be surprising that there are many ways to separate brain parts. Brain parts can be separated on the basis of what they look like to the naked eye, under a microscope, or by what certain brain parts do. The brain and spinal cord make up the central nervous system and all of the nerves found in our body make up the peripheral nervous system. When you see a picture of the brain you probably think of a wrinkled gray blob. Well, the wrinkles are called cortex and it is where the majority of brain cells or neurons reside. The cortex can be divided into four main lobes. The frontal lobe, where you do your heavy thinking, pondering and planning your actions; temporal cortex, where you process sounds and form memories; occipital cortex, where you process all the things that you see; and parietal cortex, where you integrate or makes sense of all of the different bits of information that are bombarding your brain.
The Hindbrain
Having evolved hundreds of millions of years ago, the Hindbrain or the Reptillian Brain is the oldest part of the human brain. As you might guess from it's name, it's a piece of brain anatomy that we share with reptiles and is the most primitive. Likewise it's in charge of our primal instincts and most basic functions. Things like the instincts of survival, dominance, mating and the basic functions of respiration, heartbeat all come from this area of the brain. Located in the Hindbrain are:
This is the infomation superhighway of the body. It carries information up to the brain and instructions back down.
Helps control the body's autonomic functions (things you don't need to think about to perform) like respiration, digestion and heart rate. Also acts as a relay station for nerve signals going to/from the brain
Has roles in your level of arousal or conciousness and sleep. Relays sensory information to/from the brain. Also involved in controlling autonomic body functions.
Mostly deals with movement. It regulates and coordinates movement, posture and balance. Also involved in learning movement.
The Limbic System
The Limbic System sometimes called the "emotional brain" or "Old Mammalian Brain" is the next brain to have evolved in the more primitive mammals about 150 million years ago. This is where our emotions reside, where memory begins and where these two functions combine together to mark behaviours with positive or negative feelings. It's where mostly unconcious value judgements are made. Information going through the Limbic System are filed under "agreeable or disagreeable". It also plays a role in salience (what grabs your attention), spontaneity and creativity. Located in the Limbic System are:
It's name is latin for almond which relates to its shape. It helps in storing and classifying emotionally charged memories. It plays a large role in producing our emotions, especially fear. It's been found to trigger responses to strong emotion such as sweaty palms, freezing, increased heart-beat/respiration and stress hormone release.
This guy is all about memory and a little about learning. It's primary role is in memory formation, classifying information, long-term memory. Like the RAM in your computer it processes and stores new and temporary memory for long term storage. It's also involved in interpreting incoming nerve signals and spatial relationships.
It should be called the Hyperthalamus because it does so much. It's linked closely with the pituitary gland to control many of the body's functions. It monitors and controls your circadian rhythms (your daily sleep/wake cycle), homeostasis (making sure your body is running smoothly), apetite, thirst, other bodily urges and also plays a role in emotions, autonomic functions and motor functions.
The Thalamus is THE relay station in the brain. Most of the sensory signals, auditory (sound), Visual, Somatosensory (from your skin and internal organs), go through this organ on their way to other parts of the brain for processing. It also plays a function in motor control.
The Neocortex
The last and most advanced brain to evolve to date is called the Neocortex, neomammalian or rational brain. We share this part of our brain with other higher level mammals like the primates and dolphins, although in humans the neocortex is the largest. It takes up 2/3's of the human brain. This is where we find the brain power to develop language, abstract thought, conciousness and imagination. Let there be no doubt, this is what grants us our status on the food chain and allows us to be human.
The Neocortex is divided into two hemispheres, right and left. The right side of the brain controls the left side of the body and vice versa. Also the hemispheres are divided in terms of what kind of thought they process or produce. The right being more concerned with the artistic, spatial and musical. While the left is more concerned with the colder, linear, rational and verbal aspects. Located in the Neocortex are:
This is the most recent evolutionary addition to the brain. If the brain had a White House it would be here. It is the true center for command and control in your body. The Frontal lobe is responsible for functions such as reasoning, problem solving, judgement, impulse control. This coupled with the fact that it's the last to develop when we are young adults, probably answers a lot of questions for many parents out there. It also manages our higher emotions such as empathy and altruism. This lobe is also involved in motor control and memory.
The Parietal Lobe is involved in processing pain and touch sensation. It's where the Somatosensory (from your skin and internal organs) Cortex resides. It's also associated with cognition (including calculating location and speed of objects), movement, orientation, recognition and speech.
The Temporal Lobe is involved in auditory (sound) sensation and is where the Primary Auditory Cortex and on the left hemisphere, Wernicke's Area (language recognition) are located. This lobe is also involved in emotion, memory and speech.
The Occipital Lobe controls visual sensation and processing. The Visual Cortex is resides here.
This part of the cortex controls speech, language recognition and facial nerves.
This is the neural bridge that connects the two hemispheres to each other, located centrally in brain.
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