Download Nervous System

Nervous System
Nervous System
• Helps you observe
and react to the world
around you
• Neuron= cells of the
nervous system
Neuron Structure
dendrites
nucleus
Myelin sheath
axon
axon endings
Cell body
Neuron Structure
• Dendrites = receive impulses (messages)
• Axon = send messages away
• Myelin sheath = insulates axon to speed
up the message
3 Neuron Types
• Sensory = carry
messages from the
senses to the
brain/spinal cord
• Interneurons = in the
brain and spinal cord,
process the
messages
• Motor = carry
messages to muscles
Reflex Arc
• The nerve pathway
that consists of a
sensory neuron,
interneuron, & motor
neuron.
Nerve Impulse
• Electrical charge traveling down a neuron
**also called an ACTION POTENTIAL
http://library.thinkquest.org/25500/emotions/media/neuron.gif
Synapse
• Synapse = open space between neurons
• Neurotransmitter = chemical messenger
released by the axon endings
Organization of the Nervous
System
Chapter 33.2
Central Nervous System
• Brain & spinal cord
• Coordinates all of
your bodies activities
3 Brain Divisions
1. Cerebrum
-Conscious activities, intelligence,
memory, language, skeletal muscle
movements, senses
3 Brain Divisions
2. Cerebellum
-back of brain
-balance, posture, coordination
3. Medulla Oblongata
-brain stem
-involuntary activities
Peripheral Nervous System
• Sensory and motor
neurons
2 Divisions of the PNS
1. Somatic Nervous System = Relays
information to and from the skin and
skeletal muscles **voluntary**
2 Divisions of the PNS
2. Autonomic NS = Relays info to internal
organs **involuntary**
a.) Sympathetic NS = in control when body
is in stress (flight or fight)
b.) Parasympathetic NS = in control when
body is at rest