Divisions of the nervous system
Central Nervous System (CNS)
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The central nervous system (CNS) is composed of the brain and spinal cord alone. The brain itself is split up into four major lobes, those being:
Frontal Lobe: Responsible for reasoning and social skills. This area is strongly linked to emotions and self-control
Parietal Lobe: Responsible for your awareness of your presence in the space around you. This is an area that is active when you are navigating your world and trying to orient yourself.
Temporal Lobe: Responsible for language production and comprehension.
Occipital Lobe: Responsible for vision and filling in gaps such as blind spots and optical illusions.
*Each lobe is present TWICE in the brain because there are two halves of the brain, each half has 4 lobes.
Protection
Your brain is protected by three membranes and it should be! Something as valuable as your brain deserves the best, so it has what we call meninges which cover the brain and ensure it does not get damaged.
*Like all helmets and protective gear, there is a hard outer shell with softer inner shells. This provides the most protection upon impact. Our brains have a similar structure with the outermost layer of protection being hard, followed by softer inner layers. Your brain floats around in a solution known as cerebrospinal fluid (CSF) which allows the brain to calmly levitate and minimizes potential damage.
Frontal Lobe: Responsible for reasoning and social skills. This area is strongly linked to emotions and self-control
Parietal Lobe: Responsible for your awareness of your presence in the space around you. This is an area that is active when you are navigating your world and trying to orient yourself.
Temporal Lobe: Responsible for language production and comprehension.
Occipital Lobe: Responsible for vision and filling in gaps such as blind spots and optical illusions.
*Each lobe is present TWICE in the brain because there are two halves of the brain, each half has 4 lobes.
Protection
Your brain is protected by three membranes and it should be! Something as valuable as your brain deserves the best, so it has what we call meninges which cover the brain and ensure it does not get damaged.
*Like all helmets and protective gear, there is a hard outer shell with softer inner shells. This provides the most protection upon impact. Our brains have a similar structure with the outermost layer of protection being hard, followed by softer inner layers. Your brain floats around in a solution known as cerebrospinal fluid (CSF) which allows the brain to calmly levitate and minimizes potential damage.
Reflex Arcs |
Ever touch a hot stove or burn your hand on hot tea? Think back to what happened. Did you think about moving your hand away or was it automatic? What if you were told that the signal never reached your brain!
Reflex Arcs are built in security systems that make sure we react as fast as possible to prevent damage to ourselves. These mechanisms increase our chances of survival, and act primarily through the spinal cord. An interneuron takes the message going towards the brain and intercepts it, sending a direct response to the muscle to contract or relax. Of course, only very simple actions can be reflexes, otherwise they would recruit the action of the brain and take more time. |
Peripheral Nervous System (PNS)
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The peripheral nervous system (PNS) involves all the senses and anything outside of the central nervous system. Within the peripheral nervous system, we have the somatic nervous system (SNS) which is the 5 senses, and the autonomic nervous system (ANS) which involves automatic responses.
Within the ANS, we have two other systems, the sympathetic nervous system and the parasympathetic nervous system.
The sympathetic nervous system is activated when someone is in danger and needs to act quickly. For example, if you are being chased by a bear, you need to either run as fast as possible and escape, or fight the bear and attempt to survive. Here are the two scenarios:
Run: blood rushes to the necessary muscles and all metabolic processes that may not involve what you need to do in this exact moment stop. Your body focuses on running and running alone. To the point where trying to remember the situation later may be difficult because you were so focused on escaping. Thus, you lose some of the details because your attention was elsewhere.
Fight: Blood rushes to the important muscles for fighting and you may immediately get a surge of strength and adrenaline to fight off the bear. Your body focuses on fighting alone for survival and no resources are wasted.
This response is called the "fight or flight" response since the body goes on overdrive to either fight the situation or run away. This response is not controllable and is fully automatic.
Within the ANS, we have two other systems, the sympathetic nervous system and the parasympathetic nervous system.
The sympathetic nervous system is activated when someone is in danger and needs to act quickly. For example, if you are being chased by a bear, you need to either run as fast as possible and escape, or fight the bear and attempt to survive. Here are the two scenarios:
Run: blood rushes to the necessary muscles and all metabolic processes that may not involve what you need to do in this exact moment stop. Your body focuses on running and running alone. To the point where trying to remember the situation later may be difficult because you were so focused on escaping. Thus, you lose some of the details because your attention was elsewhere.
Fight: Blood rushes to the important muscles for fighting and you may immediately get a surge of strength and adrenaline to fight off the bear. Your body focuses on fighting alone for survival and no resources are wasted.
This response is called the "fight or flight" response since the body goes on overdrive to either fight the situation or run away. This response is not controllable and is fully automatic.