The Structure of the
Nervous System
Divisions of the Nervous System
The Nervous System:
Central Nervous System
CNS
Peripheral Nervous Systems
PNS
Central
Nervous
System (CNS):
- brain
- spinal cord
Peripheral Nervous System (PNS)
• The nerves that connect the CNS to the
rest of the body
• The system is subdivided into the
somatic and autonomic nervous
systems.
Autonomic Nervous System
• Monitors the autonomic functions
(breathing, blood pressure, digestion)
• Divided into the sympathetic and
parasympathetic nervous systems
Sympathetic Nervous System:
In charge of arousal
responses such as “fight
or flight” (helps us deal
with perceived threats)
Parasympathetic Nervous System:
Calms the body and brings
it back to a relaxed state
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
HOW DOES THE
NERVOUS SYSTEM WORK?
I. Neuron - The basic building block
of the nervous system (a nerve cell)
• Receive, Carry, and Pass
information on to the next
neuron
Parts of the Neuron
Dendrites
• Receive information into
the cell body.
Soma - cell body of a neuron
Nucleus: the
organelle that
is located in
the center of
the cell body
of a neuron.
Axon - takes information away
from the cell body.
Myelin Sheath: Fatty material
that surrounds some axons
•its purpose is to
protect the axon
and speed
processing.
Axon Terminal: the
end of the neuron,
it releases
neurotransmitters
into the synaptic
cleft
Neurons
Neuron
Neural
Communication:
The Neural Impulse
1. Action Potential
• A brief electrical charge that travels
down the axon of the neuron.
2. Neurotransmitters: Chemical
messengers that are released
into the synapse.
a. Examples: Acetylcholine
(movement), Serotonin (mood)
b. Are also found in psychiatric
medications and other
substances
• Antagonists: block
neurotransmitters if you have too
much (ex: People with
Schizophrenia have 6x the proper
level of dopamine!)
• Agonists: mimic neurotransmitters
when you don’t have enough (ex:
Depression is caused by low levels
of serotonin.)
3. Synapse: A space or “junction”
between two neurons
• The gap where
neurotransmitters are
released by one
neuron and absorbed
by the next neuron
Neurotransmitters
How Do Neurons Communicate?
• First, neurotransmitters are received by
the dendrites.
• Then, the information is processed by the
soma.
• Next, an action potential occurs, sending
information down the axon.
• Finally, neurotransmitters are released at
the axon terminal for the next neuron to
absorb.
C. Types of Neurons
• Sensory - carry information to the central
nervous system from the sensory organs
(eye, ear, skin, etc.)
• Motor - carry information from the
central nervous system to the muscles and
glands
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain