Download The Nervous System

The Nervous System
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The Nervous System
• Regulates our internal functions
• Involved in how we react to the external
environment
• Two main parts
– Central Nervous System
– Peripheral Nervous System
Neurons
• Nerve cells that run through our entire
body and communicate with each other
• Receive messages from parts of the
body (muscles, glands, etc)
• 100 Billion in our bodies, mostly in the
brain
• Neurons are composed of:
– Cell body (soma): directs actions of the cell
– Dendrites: extensions that receive
information
– Axon: extends from cell body, carries
electrical potential, sends a chemical
message to adjacent neurons via terminal
buttons
Neurons are for Communicating
Messages are sent
from the axon
terminals of one
neuron to the
dendrites of
another
Synapse
• In order for the message to send from
neuron to neuron they must cross the
synapse
• The message only goes in one direction
Dendrites > Cell Body > Axon > Axon
Terminals > Dendrites…..
Synapse
Neurotransmitters
• Neurons send messages across the
synapse through the release of
neurotransmitters
• Chemicals stored in sacs in the axon
terminals
• Several types, each with a specific
structure and can only fit into a specific
receptor site
Types of Neurotransmitters
• Serotonin – affects mood, sleep, sensory
perception, and other functions, may play a role in
psychological disorders like depression
• Acetylcholine – involved in memory, muscle action,
sleep, emotions, those w/ Alzheimer’s have lower
levels
• Dopamine – affects movement, attention, memory,
learning, plays role in addiction
• Norepinephrine – affects learning, memory,
emotions, eating, alertness, etc.
• Epinephrine – emotions, memory storage…
Central Nervous System
• Made up of:
– Brain (we will talk about this later)
– Spinal Cord
• Extends from the brain down the back
• Column of nerves, as thick as your thumb
• Spinal Reflexes
– When your knee kicks at the doctors office
– Blinking when you get something in our eye
QuickTime™ and a
decompressor
are needed to see this picture.
Peripheral Nervous System
• Responsible for transmitting messages
between the CNS and the rest of the
body
• Two Main Systems in the PNS:
– Somatic Nervous System
– Autonomic Nervous System
Somatic Nervous System
• Transmits messages to the CNS
• Activated by touch, pain, changes in
temperature or changes in body
positions
• Sends messages to muscles and
glands
Autonomic Nervous System
• Regulates the body’s vital functions
– Heartbeat, breathing, digestion, etc.
• Two divisions:
– Parasympathetic
– Sympathetic
Autonomic Nervous System
Parasympathetic
• Restores bodies
energy after an
action has occurred
• Slows down
heartbeat, digestion,
breathing
Sympathetic
• Fight or flight
response
• Activated when the
body is put in a
stressful situation