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THE NERVOUS SYSTEM - Coggle Diagram
THE NERVOUS SYSTEM
At the Microscopic level : The Neutron
No matter which branch you're in , the fundamental units is the Neuron.
Dendrites: Receive Signals
Axon: Passes signals to other neurons or muscle.
Myelin Sheath: The "insulation" that speeds up signal travel.
Central Nervous System (CNS)
The Control center , this is where information is processed and decisions are made.
Brain: The master computer, includes the cerebrum (Thought) Cerebellum (Balance) ,and brainstem (Vital).
Spinal Cord: The superhighway. It transmits signals between the brain and the rest of the body and handles quick reflexes.
Peripheral Nervous System (PNS)
The communication lines , These are the nerves that branch out from the CNS to the rest of the body. It is divided into two main functional paths.
Sensory ( Afferent ) Division : Carries impulses
toward
the CNS from sensory receptors ( like your skin or eyes ).
Motor ( Efferent ) Division : Carries impulses away from the CNS to muscles and glands.
Sub-division of the Motor ( Efferent ) System.
This is where the body decides if an action is Voluntary or Automatic.
Somatic Nervous System: Controls voluntary movements
( e,g waving your hand or walking). It targets skeletal muscle.
Autonomic Nervous System ( ANS ): Controls involuntary functions ( e,g heartbeat , digestion ). It targets smooth muscle, cardiac muscle, and glands.
The Autonomic " Toggle Switch "
The ANS is further broken down into two states of being:
Sympathetic Division: The "Fight or Flight " system. It kicks in during stress or exercises ( increases heart rate, dilates pupils).
Parasympathetic Division: The "Rest and Digest" system. It calms the body down and conserves energy ( lowers heart rate, stimulates digestion).
How Neurons talk: The Synapse
Information doesn't just flow through wires, it has to jump gaps. This happen at the synapse, the junction between two neurons.
Action Potential: An electrical impulse travel down the axon.
Neurotransmitters: When the impulse reaches the end, it triggers the release of chemical messengers ( like Dopamine or Serotonin).
Receptors: These chemicals "dock" onto the next neuron, passing the message along.
The Reflex Arc: A Shortcut
Sometimes the brain is slow . If you touch the hot stove, your Spinal Cord takes over to save time. This is called a Reflex arc.
Receptor: Senses of heat
Sensory Neuron : Sends a "danger" signal toward the spine.
Interneuron: In the spinal cord , it immediately passes the signal to a motor neuron ( bypassing the brain's "thinking" process).
Motor Neuron: Tells your arm muscle to contract.
Effector: you pull your hand away before you even feel pain.