Nervous System Notes

The Workings Of Mind And Body
The Nervous System: The Basic Structure
1. How does the nervous system work?
a. Part of the body that coordinates actions and transmits signals between different
parts of the body
b. Never resting
c. Central Nervous System (CNS)- the brain and the spinal cord
i. Spinal Cord- nerves that run up and down the length of the back and
transmit most messages between the body and brain
d. Peripheral Nervous System (PNS)- nerves branching beyond the spinal cord into
the body
e. Nerves-Strings of neurons
f. Neurons- long, thin cells of nerve tissue along which messages travel to and from
the brain
i. Parts Of A Neuron
1. Dendrites- Short, thin fibers that protrude from cell body; receive
messages from other neurons and send them to cell body
2. Axon- carries impulses from the cell body to the axon terminals
3. Axon Terminals- release neurotransmitters to stimulate dendrites
4. Myelin Sheath- white, fatty substance that insulates and protects
5. Schwann Cell- Cells that surround and protect neurons
6. Node Of Ranvier- Gap in Myelin Sheath
ii. Synapse- gap that exists between individual nerve cells
iii. Neurotransmitters- chemicals released by neurons which determine the
rate at which other neurons fire
1. Ie. Norepinephrine- memory and learning, endorphin-inhibits
pain, serotonin (undersupply=depression), dopamine
(oversupply=schizophrenia), glutamate (oversupply=epilepsy)
iv. Ascending  sensory impulses to brain
v. Descending  motor impulses from brain
g. Voluntary And Involuntary Activities
i. Somatic Nervous System (SNS)- part of the PNS that controls voluntary
movement (raising hand, turning page)
ii. Autonomic Nervous System (ANS)- part of the PNS that controls internal
biological functions (heart beat, breathing, blood pressure)