Structure of the Nervous System

Week 2/Chapter 2: Structure of the Nervous System
The hot-linked text below will take you to the relevant section of the GetBodySmart tutorial.

The nervous system is made of TWO types of cells (NOT discussed in the textbook)

• neurons - actively communicate by synaptic connections (electro-chemical process)
• glial cells - support cells, protect and increase speed of communication (myelin sheath)
• 110,000,000,000 neurons and about 50x that number of neuroglia
  

Traditional 3 parts of the Nervous System:

CNS = central nervous system

• brain - the central processing unit
  
• spinal cord - pathways going up and down, as well as reflexes ('u-turns', 2 neuron reflex)
  

PNS = peripheral n.s.; mostly enters or exits holes in the spinal cord or vertebrae

• carries information from receptors in the body to the spinal and then UP to brain
• carries information coming DOWN spinal cord to effectors in the body (muscles, glands)
• specialized cranial nerves (12 total) enter or exit holes in the cranium, not the spinal cord
  

ANS = autonomic n.s.; made up portions of both CNS & PNS, 'automated' control of body:

• Sympathetic branch: activation/arousal, flight or flight response, emotion
  
• Parasympathetic branch: recuperation, relaxation, rejuvination

Divisions of the Brain

Major Divisions of the adult brain - tutorial goes top-down...
Each division is made up of a number of specific neuroanatomical structures.
Beumont presents the divisions bottom-up... lower functions first.

• brainstem - basic body functions (medulla oblonglata, pons, midbrain)
  
• cerebellum - motor coordination & motor learning, posture
• diencephalon - subcortical forebrain - emotion, motivation, awareness (thalamus, etc.)
• telencephalon - 'forebrain' - cerebrum - cerebral cortex - outer layer, newest, cognition
• CORTEX will be described in greater detail as we address the lobes in the coming weeks

Organizational Features of the Cerebrum

• Right and left hemispheres of the cerebrum/telencephalon
  
• Four lobes and their boundaries
  
• White matter and gray matter
• Primary or secondary cortex
• "Decussation", contra-lateral representation, or cross-over
  
• Primary