Nervous System. Helps you observe and react to the world around you Neuron= cells of the nervous...
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Transcript of Nervous System. Helps you observe and react to the world around you Neuron= cells of the nervous...
Nervous System
Nervous System
• Helps you observe and react to the world around you
• Neuron= cells of the nervous system
Neuron Structure
nucleus
dendrites
Myelin sheath
Cell body
axon
axon endings
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