Nervous System

The nervous system coordinates sensation, movement, emotion, behavior, and communication between all organs. It includes the brain, spinal cord, peripheral nerves, autonomic nervous system, and the enteric “second brain.” Through electrical and chemical signaling, it regulates stress responses, rest-and-digest functions, thought, memory, perception, and every muscular action in the body.
Transmits and interprets all sensory informationControls skeletal, cardiac, and smooth muscle movementRegulates organs and glands through ANSGenerates emotions and behavioral responsesCoordinates reflexes and survival responsesMaintains homeostasis through neuroendocrine regulationSupports cognition, memory, focus, and attentionIntegrates stress responses and recovery statesCentral Nervous System (CNS): brain, brainstem, spinal cordPeripheral Nervous System (PNS): sensory & motor nervesAutonomic Nervous System (ANS)- Sympathetic: fight-or-flight
- Parasympathetic: rest-and-digest
- Regulated by the hypothalamus
Enteric Nervous System: surrounds and manages digestion (“second brain”)Spinal Cord Anatomy:- Continuous with medulla oblongata
- Ends at L1 vertebra
- Cauda equina nerve bundle
- White matter tracts + gray matter nerve cell bodies
Neuron Structure:- Soma, nucleus
- Dendrites
- Axon & axon hillock
- Myelin sheath (fat-based)
- Schwann cells
- Nodes of Ranvier
- Synapse (axon-to-dendrite junction)
Neurotransmitters:- Acetylcholine
- Norepinephrine / Epinephrine
- Dopamine
- Serotonin
- GABA
- Glutamate
- Endorphins
- Substance P