1. The Nervous System
Peripheral Nervous System
Central Nervous System

2. Functions of the Nervous System
Your nervous system controls the actions and reactions of the body in response to stimuli.
receives information
responds to stimuli
maintains homeostasis

3. Organs of the Nervous System
The nervous system consists of:
brain
spinal cord
nerves
neurons
sense organs

4. Maintaining Homeostasis
The nervous system maintains homeostasis by directing the body to respond correctly to the information it receives.
When you are hungry, your brain tells you to eat

5. Central Nervous System
Vocabulary Word!
central nervous system – composed of the brain and spinal cord.
brain – receives and processes information from inside and outside your body.
spinal cord – thick column of nerve tissue that links the brain to nerves in the rest of your body.

6. Peripheral Nervous System
Vocabulary Word!
peripheral nervous system - network of nerves that connects your brain to the rest of your body.
Made up of 43 pairs of nerves
12 begin in the brain
31 begin in the spinal cord
One nerve in each pair goes to the right side and one to the left

7. brain
Vocabulary Word!
brain – receives and processes information from inside and outside your body.
The skull, layers of connective tissue, and fluid protect the brain from injury

9. cerebrum
Vocabulary Word!
cerebrum – largest part of the brain that controls thinking, problem solving, the senses and memories.
reads input from the senses
controls skeletal muscles
In charge of learning, remembering and making judgments

10. Cerebrum Right side Left side controls left side of body
controls creativity and artistic ability
Left side
controls right side of body
Controls math, speech, writing, and logic

11. cerebellum
Vocabulary Word!
cerebellum - second largest part of your brain that coordinates your muscles and controls your balance.

12. brain stem
Vocabulary Word!
brain stem – connects your brain to your spinal cord and controls involuntary actions like breathing, digesting and heartbeat.

13. spinal cord
Vocabulary Word!
spinal cord – a bundle of nerves that links your brain and peripheral nervous system.
Protected by bone, connective tissue and fluid

14. Receiving Information
Because of your nervous system, you are aware of what is happening in the environment around you.
Your brain is also aware of your internal conditions like temperature and glucose level.

15. Responding to Stimuli
After receiving information, your nervous system analyzes the data and causes a response.
Putting your hand in front of your face if a ball is coming at you.
Increasing your heart rate when exercising.

16. Responding to Stimuli
Your nervous system works by receiving information from inside or outside the body and turning that info into an electrical signal.
The messages are sent out along special cells called neurons.

17. Vocabulary Word!
neuron - a cell that moves messages in the form of fast-moving electrical energy called impulses.

18. The Neuron Neurons are cells that carry information around your body.
Nerve impulse - The message a neuron carries

19. The Neuron The cell body of the neuron has two extensions
dendrite – carries impulses to the cell body. A neuron can have lots of dendrites.
axon – carries impulses away from the cell body. A neuron only has one axon.
The nerve impulse begins in the dendrite, moves to the cell body then moves down the axon.

20. The Neuron
signal goes from axon to dendrite

21. Kinds of Neurons
Different kinds of neurons perform different functions
sensory neurons
motor neurons

22. Sensory Neuron
sensory neuron – gathers information from the internal or external environment and converts each stimulus into a nerve impulse.
The impulse travels along the sensory neuron until it reaches an interneuron in the brain or spinal cord
sensory impulse travels at 76.2 m/s

23. Motor Neuron
motor neuron – moves nerve impulses from the brain and spinal cord to the rest of the body.
Motor impulse travels at 119 m/s

24. How a Nerve Impulse Travels
Millions of nerve impulses travel your body each day.
The nerve impulse travels along the neuron in the form of electrical and chemical signals.

25. How a Nerve Impulse Travels
synapse - tiny space between the axon of one neuron and the dendrites of the next.
A nerve impulse must jump this gap.
Axon tips release a neurotransmitter that allows the impulse to travel the gap.

26. How a Nerve Impulse Travels
Drugs and alcohol can affect the neurotransmitters
depressants, like alcohol and
marijuana slow reaction time
stimulants, like meth, speed up
reaction time

27. The Path of a Nerve Impulse

28. Reflex
reflex - is an automatic response that occurs very rapidly and without conscious control.
Reflexes protect us from pain and injury.

29. Reflexes

30. the senses The senses gather information for the nervous system. sight
touch
hearing
taste
smell

31. Body systems that work with the nervous system;
The nervous system works with every system in the body.

32. Comparing Cells to the Body
The cell part that controls the cell is the
nucleus