1. NERVOUS SYSTEM

2. Functions of the Nervous System
To receive (in the brain) information (stimuli) from sensory receptors
RECEPTORS = Specialized cells that receive information from the environment
Ex: rods and cones in the retina of your eye
SENSE ORGANS = Organs containing special receptor cells
Ex: Eyes
SENSORY RECEPTORS
SENSE ORGAN

3. Functions of the Nervous System
To interpret (make sense of) sensory impulses
This happens when signals go from the sensory receptors to the brain
To send out impulse instructions (response) to muscles and glands
The brain sends instructions for action to muscles
The brain sends instructions to glands to release hormones

4. THOUGHT QUESTION…
Which cell organelle most closely corresponds to the nervous system?
The nucleus because the nucleus controls the cell and the nervous system controls the body.

5. Nervous System ORGANS Brain Spinal Cord TISSUES = Nerves
CELLS = Neurons (nerve cells)
Dendrite
Axon
Synapse

6. The Nervous System has two parts
CNS
Central Nervous System
Brain makes all the decisions
Some voluntary, some involuntary
Decisions are sent out to spinal cord
PNS
Peripheral Nervous System
Network of nerve pairs
Brain signals are delivered by spinal cord
Most nerves branch off of spinal cord
Sends signals to brain for decision making

7. The Central Nervous System is made up of
the BRAIN and the SPINAL CORD.

8. CENTRAL NERVOUS SYSTEM Organ - Brain
Main organ
Weighs about 3lbs
Protected by cranium
Covered by a tough membrane
Contains different structures that perform different functions

9. HUMAN BRAIN

10. CENTRAL NERVOUS SYSTEM Organ – Spinal Cord
Connects the brain to the nerves in the whole body
Nerves branch off of the spinal cord at different levels to go to the body
Protected by the bony spinal column of vertebrae

11. The Peripheral Nervous System is made of a network of nerves that
Connect the brain and spinal cord to
the rest of the body.

12. PERIPHERAL NERVOUS SYSTEM Tissue- Nerves
Long fibers that lead to all parts of the body from the spinal cord
Fibers may be in the form of bundles like a rope made of smaller fibers

13. How the
CNS and PNS
fit together
in the body

14. THOUGHT QUESTIONS… What is the main organ of the nervous system?
The brain 
What makes up the CNS?
The brain and spinal cord
What makes up the PNS?
The network of nerves that connect the brain and spinal cord to the rest of the body

15. Nerve Cells are called NEURONS
-long cells
-cell body on one end
-nucleus in cell body
-dendrites branch off
-long part is axon
-shaped like a hand!

16. How Neurons Work Together
You have many neurons, all over your body.

17. The neurons are lined up, dendrite end to axon end.
Each dendrite is very close to the axon end of another neuron.This forms a complex network.

18. There are tiny spaces between the neurons, called SYNAPSES.
Electrochemical signals or impulses travel through the
network and have to ‘jump’ across these little spaces.

19. Neurons pass impulses to each other and
form a network all through the body.

20. Sensory Receptors Types of sensory receptors Types of sensory organs
Touch
Pain
Heat
Cold
Pressure
Smell
Taste
Types of sensory organs
Eyes
Ears
Nose
Skin
Tongue

21. 3 TYPES OF NEURONS
Muscle Fiber

22. THOUGHT QUESTIONS What are the tissues of the nervous system?
Nerves
What are nerve cells called?
Neurons
What are the structures that make up a nerve cell?
Axon, cell body, dendrite
What is the gap between neurons called?
Synapse
How do impulses travel through neurons?
Electrochemical signals are picked up by the dendrites, travel to the cell body and then away from the cell body through the axon. The signal jumps across the synapse to the dendrites of another neuron
What kinds of neurons are there?
Sensory neurons, interneurons and motor neurons

23. Sensory Receptors
Neurons in different parts of your body receive signals from sensory receptor neurons… called STIMULI
Those signals are sent to the spinal cord and brain by the network of neurons.
The brain has interneurons that process the information and decide on a reaction, called a RESPONSE that is sent out through motor neurons

24. NERVOUS SYSTEM AT WORK

25. Path of an Impulse

26. Stimuli and Response (Cause and Effect)
SENSORY
RECEPTORS
BRAIN’S
DECISION
STIMULUS
RESPONSE
Skin senses cold
Goosebumps help warm you up
Nose smells good food
Hunger prompts you to eat
Skin senses pain from an insect bite
White blood cells rush to the scene

27. Different
sensory receptors
have different
shapes!

29. THOUGHT QUESTIONS
What is the proper term for something that CAUSES a change?
Stimulus
What is the proper term for the EFFECT of a stimulus?
Response
What are the five sensory organs?
Eyes, ears, tongue, nose, skin

30. Check for Understanding
What is the name of a nerve cell?
What shape is a neuron?
On your ‘hand’ neuron, where is the nucleus?
Where are the dendrites?
Where is the axon?
How are neurons connected?
What is the ‘gap’ between neurons called?
What are the organs of the central nervous system?
What is the major decision maker?
What is the function of the spinal cord?
Describe the peripheral nervous system.
What is the proper term for something that CAUSES a change?
What is the proper term for the EFFECT of a stimulus?
What are the five sensory receptors?