biology
nwaf
nervoussystem.pptThe Nervous System
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Brain Teaser
15 14 9 1 6 3
Which number comes next in the sequence?
4,7,10 or 12 ?
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Functions of the Nervous System
Control center for all body activities
Responds and adapts to changes that occur both inside and outside the body
(Ex: pain, temperature, pregnancy)
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Central Nervous System
Neurons : microscopic nerve cells that make up the brain, spinal cord, and nerves
- 30,000 neurons can fit on a pinhead
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Anatomy of a Neuron
Each neuron contains:
- Cell body with nucleus
- Dendrites : fibers that receive messages from other neurons
- Axons : fibers that send messages to other neurons
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- Neurons do NOT touch; there is a gap between them called a synapse
- Messages are sent across the synapses by special chemicals called neurotransmitters
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Communication Between Neurons
The use of neurotransmitters causes an electrical current
There is enough electrical current in the brain to power a flashlight
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Brain Teaser
If you were running a race, and you passed the person in 2nd place, what place would you be in now?
Second
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Two Major Divisions of the Nervous System
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Central Nervous System
Brain : a mass of 100 billion neurons located inside the skull
-Learning occurs as more and stronger connections are made between neurons
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Anatomy of the Brain
Cerebrum : largest part of human brain
- Responsible for:
- Thought
- Language
- Senses
- Memory
- Voluntary movement
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Retrieval of a Memory
A memory is not a snapshot stored in the brain – it must be put together from information stored in various parts of the brain
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Anatomy of the Brain
Cerebellum : at base of brain
-Responsible for:
- Muscle coordination
- Balance
- Posture
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Anatomy of the Brain
Brain Stem : connects brain to spinal cord
-Responsible for:
- Breathing
- Swallowing
- Heartbeat
- Blood pressure
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Central Nervous System
Spinal Cord : Column of nerves from brain to tailbone – protected by vertebrae of spine
Responsible for:
- Conducting impulses between the brain and the rest of the body
*Impulses may travel as fast at 268 miles/hr
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Brain Teaser
A H I M N O T U V W
Which of the letters above does not belong with the rest?
N It is not a mirror-image of itself
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Peripheral Nervous System
Nerves : visible bundles of axons and dendrites that entend from the brain and spinal cord to all other parts of the body
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-Responsibilities:
- Sensory nerves - carry messages from body to brain (pain, pressure, temperature)
- Motor nerves – carry messages from brain to body to respond
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Brain Teaser
There is a town where 5% of all the people living there have unlisted phone numbers. If you selected 100 names at random from the town’s phone directory, on average, how many of these people would have unlisted phone numbers?
0 They would not be in the phone book if their number was unlisted
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Problems of the Nervous System
Concussion
A temporary disturbance of the brain’s ability to function due to a hard blow to the head
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Paralysis
A loss of sensation and movement of part of the body due to an injury of the spinal cord or brain
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Parkinson’s Disease
The brain does not produce enough of the neurotransmitter that transmits messages from the brain to the muscles
Symptoms: tremors, rigid muscles, shuffling walk, and loss of facial expression
Red areas show where chemical is stored
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Alzheimer’s Disease
A gradual shrinking of the neurons in the cerebrum
Symptoms: memory loss, emotional disturbances, inability to function on own, death
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Epilepsy
Abnormal transmission of messages between the neurons in the brain
Symptoms: seizures
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