Overview of the Nervous System

learning_notes

Last updated: 8/16/2025

Nervous System = CNS + PNS, central vs peripheral

Central Nervous System (CNS): brain + spinal cord

Spinal cord: reflexes (reflex arc: sensory receptor -> afferent neuron -> interneuron (spinal) -> efferent neuron -> effector/muscle cells), faster than brain (e.g. hands retract from fire faster than sensation of pain)

Peripheral Nervous System (PNS): ANS + somatic (motor neuron) *all responses from ANS, para/sympathetic, and somatic belong to PNS

Autonomic Nervous System (ANS): sympathetic + parasympathetic *all responses from para/sympathetic belogn to ANS

Sympathetic Nervous System: aroused, heart faster, breath faster, sweat, dry eyes, dilation of pupils and bronchi (lung - throat), blood sugar high, blood pressure high, ready to run, "fight or flight", adrenal glands, adrenaline/epinephrine

Parasympathetic Nervous System: relaxed, calm, heart slow, stomach digest, sleepy, more tear

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