1. Nervous System

2. Nervous System Helps you observe and react to the world around you
Neuron= cells of the nervous system

3. Neuron Structure dendrites Myelin sheath nucleus axon axon endings
Cell body

4. Neuron Structure Dendrites = receive impulses (messages)
Axon = send messages away
Myelin sheath = insulates axon to speed up the message

5. 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

6. Reflex Arc
The nerve pathway that consists of a sensory neuron, interneuron, & motor neuron.

8. Nerve Impulse Electrical charge traveling down a neuron
**also called an ACTION POTENTIAL

9. Synapse Synapse = open space between neurons
Neurotransmitter = chemical messenger released by the axon endings

10. Organization of the Nervous System
Chapter 33.2

11. Central Nervous System
Brain & spinal cord
Coordinates all of your bodies activities

12. 3 Brain Divisions Cerebrum
-Conscious activities, intelligence, memory, language, skeletal muscle movements, senses

13. 3 Brain Divisions 2. Cerebellum -back of brain
-balance, posture, coordination
3. Medulla Oblongata
-brain stem
-involuntary activities

14. Peripheral Nervous System
Sensory and motor neurons

15. 2 Divisions of the PNS
1. Somatic Nervous System = Relays information to and from the skin and skeletal muscles **voluntary**

16. 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