1. Unit 2: Cells and Systems
Topic 3: The Nervous System

2. Nervous System Overall, the Nervous system responds to Stimuli
Which if you remember, responding to the environment is a key factor of life!
What kind of stimuli are there?

3. Nervous System Overall, the Nervous system responds to Stimuli
Which if you remember, responding to the environment is a key factor of life!
What kind of stimuli are there?
Temperature
Light
Pressure
Sound
Body Chemistry
Dangers (burning yourself)

4. Neurons Neurons receive messages from small branches called Dendrites
Incoming messages go from the Dendrite to the Cell Body to the Axon
Axons send the messages to the following neuron’s Dendrites.
This is partly done through electrical transmission!

5. Neurons Dendrite Axon Cell Body
Neurons receive messages from small branches called Dendrites
Incoming messages go from the Dendrite to the Cell Body to the Axon
Axons send the messages to the following neuron’s Dendrites.
This is partly done through electrical transmission!
Dendrite
Axon
Cell
Body

6. Neurons

7. Organization of the Nervous System
Two main categories
1) Central Nervous System
Brain and Spinal cord
2) Peripheral Nervous System
Cranial nerves, spinal nerves, peripheral nerves

8. Central Nervous System

9. Central Nervous System
Cerebrum
Control/reaction to senses
Movement
Thinking
Cerebellum
Balance
Medulla
Breathing
Heart Rate

10. Central Nervous System
Reflexes can happen only using your Spinal Cord, not your brain!
After you react, your brain is notified and then you scream in pain, but you hand is already safe!

11. Peripheral Nervous System
The Peripheral Nervous System has two types of neurons
1) Sensory Neurons
Carry information from the body to the central nervous system
2) Motor Neurons
Carry information from the central nervous system to the body

12. Peripheral Nervous System
Lets divide the Peripheral Nervous System again, sounds like fun right?????
1) Somatic Nervous System
You can voluntarily control this
For example, You choose to walk forward
2) Automatic Nervous System
Your body automatically adjusts without your control
For example, your pupils adjust to light, or your heart rate increases when you exercise
You don’t have to tell your heart to beat!

13. Peripheral Nervous System

14. Uneven Sense of Touch
Your body has certain locations of nervous responsible for vision (eyes), hearing (ears), smell (nose) and taste (tongue)
What about touch? We can feel things everywhere on our bodies.
Some places have more touch sensory neurons than others, our hands are much more sensitive than our backs.

15. Cool Fact Some nerves grow in ways that are inconvenient
The RLN nerve, which goes from the larynx to the brain takes a detour and wraps around the aorta first-which does nothing!
It is just how nerves first evolved
Giraffes take this to the extreme, and have the nerve go all the way down their neck and back, when it could have just gone from the mouth to the brain……

16. Cool Fact
We have a neuron (1 cell) that goes from our spine to our big toe!
Called the Sciatic Nerve