1. The Nervous System
Peripheral Nervous System
Central Nervous System

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

3. The Neuron

4. The Brain

5. Functions of the Nervous System
Your nervous system is a communications network
Receiving information
Responding to stimuli
Maintaining homeostasis

6. 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

7. 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

8. 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

9. Central Nervous System
The control center of the body
Composed of your:
Brain – controls most functions
Spinal Cord – thick column of nerve tissue that links the brain to nerves in the peripheral nervous system

10. Brain The brain contains 100 million neurons
The skull, layers of connective tissue, and fluid protect the brain from injury
The brain is composed of three main parts
Cerebrum
Cerebellum
Brain stem

12. Cerebrum Largest part of the brain reads input from the senses
controls skeletal muscles
In charge of learning, remembering and making judgments

13. 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

14. Cerebellum Second largest part of your brain
Coordinates actions of your muscles
Helps you keep your balance

15. Brain Stem Lies between the cerebellum and spinal cord
Controls involuntary actions
Breathing
Heartbeat

16. Spinal Cord The link between your brain and peripheral nervous system
Protected by bone, connective tissue and fluid

17. Peripheral Nervous System
Consists of a network of nerves that branch out from the central nervous system
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

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
Axon – carries impulses away from the cell body
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
Interneurons
Motor neurons

22. Sensory Neuron
Picks up stimuli 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. Interneuron
Neuron that carries nerve impulses from one neuron to another
Can pass stimuli from sensory neuron to motor neuron

24. Motor Neuron
Send an impulse to a muscle and the muscle contracts in response
Motor impulse travels at 119 m/s

25. 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

26. How a Nerve Impulse Travels
There are tiny spaces or synapses between a neuron and the next structure
A nerve impulse must jump this gap
Axon tips release a neurotransmitter that allows the impulse to travel the gap

27. How a Nerve Impulse Travels
Drugs and alcohol can affect the neurotransmitters
alcohol increases reaction time
depressants, like marijuana
also increase reaction time
stimulants, like meth, decrease
reaction time

28. The Path of a Nerve Impulse

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

30. Reflexes

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