1. 8th Grade Science Mrs. Christopherson Mrs. Goede
The Nervous System
8th Grade Science
Mrs. Christopherson
Mrs. Goede

2. Parts of the Nervous System
Central Nervous System
Brain
Spinal Cord
Peripheral Nervous System
Nerves

3. Central Nervous System
Brain:
Divided into two hemispheres:
Left: Analytical
Right: Creative
Divided into 4 lobes, each responsible for different functions.
Frontal: complex thinking
Temporal: hearing, memory retrieval
Parietal: contains the sensory and motor cortexes
Occipital: vision

4. Central Nervous System
Spinal Cord:
Thin bundle of nerves running down the spinal column
Surrounded by a fluid that protects it from banging into the vertebrae
Function: transmits messages between the brain and the peripheral nervous system

5. Central Nervous System
Spinal Cord cont:
4 main groups of spinal nerves:
Cervical nerves: supply movement and feeling to the arms, neck, and upper body
Thoracic nerves: abdomen
Lumbar nerves: lower back
Sacral nerves: buttocks, genitals

7. Peripheral Nervous System
“Peripheral”: relating to an outer boundary
The nervous system extending from the spinal cord out to the body
Consists of:
Sensory neurons: body  the central nervous system
Motor neurons: the CNS  body

8. Peripheral Nervous System
Sub-divided into 2 parts:
Somatic Nervous System:
controls nerves that go to the skin and muscles; conscious activities (i.e.-activities you are aware of)
Autonomic Nervous System:
controls internal organs; unconscious activities (you don’t think about these functions)

9. Peripheral Nervous System
The neuron:
Dendrites: Receive messages from other neurons
Cell Body: Contains the nucleus-the control center of the neuron
Axon: Sends messages to other neurons

11. Central Nervous System Peripheral Nervous System
Consists of 2 parts:
Central Nervous System
Peripheral Nervous System
Which includes these organs:
Which is composed of 2 parts:
Brain
Spinal Cord
Somatic nervous system
Autonomic nervous system

12. The Nervous System & Our Senses
Everything we know about the world around us comes from our senses.
Touch
Vision
Hearing
Taste
Smell

13. The Nervous System & Our Senses
The brain receives sensory messages from different parts of our body
Touch: skin
Vision: eyes
Hearing: ears
Taste: taste buds
Smell: nose

14. The Nervous System & Our Senses
Our nervous system responds to change; we only react to something if it is different from what we’ve previously experienced.
Objects or sensations that remain the same tend to blend into the background; we don’t notice them
For example: our touch receptors notice the feel of our clothes when we get dressed in the morning but we soon “forget” that we have clothes on!

17. The Nervous System & Our Senses
Brain Map of the Senses

18. The Nervous System & Our Senses
As the diagram showed, when the nerves of our body sense something, a message is sent from that nerve back to the brain.
The message travels to a specific portion of the sensory cortex to be decoded
In this way, our brain tells our body what to do about the sensory situation.
E.g.: We react differently to a fly landing on our arm vs. boiling water landing on our arm!

19. The Nervous System and Our Senses