Download The Nervous System

The Nervous System
Central Nervous System
Peripheral Nervous System
Procedure
1. A starting person will be chosen and
will be given an object.
2. Once the teacher gives the signal, the
start person will pass the object to
their right.
3. Each student will take the object and
pass it to their right until it makes it
back to the starting person.
Procedure
4. DO NOT THROW THE OBJECT!
5. A time will be recorded for each trial
6. Repeat the process 2 more times and
record the times in your spiral.
Questions
• In your spiral, answer the following
questions about the demonstration.
Organs of the Nervous System
• The nervous system consists of:
– brain
– spinal cord
– nerves
– neurons
– sense organs
The Neuron
The Brain
Functions of the Nervous System
• Your nervous system is a communications
network
– Receiving information
– Responding to stimuli
– Maintaining homeostasis
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
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
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
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
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
Cerebrum
• Largest part of the brain
– reads input from the senses
– controls skeletal muscles
– In charge of learning, remembering and
making judgments
Cerebrum
• Right side
– controls left side of body
– controls creativity and artistic ability
• Left side
– controls right side of body
– Controls math, speech, writing, and logic
Cerebellum
• Second largest part of your brain
• Coordinates actions of your muscles
• Helps you keep your balance
Brain Stem
• Lies between the cerebellum and spinal
cord
• Controls involuntary actions
– Breathing
– Heartbeat
Spinal Cord
• The link between
your brain and
peripheral nervous
system
• Protected by bone,
connective tissue
and fluid
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
The Neuron
• Neurons are cells
that carry information
around your body
• Nerve impulse - The
message a neuron
carries
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
The Neuron
signal goes from axon to dendrite
Kinds of Neurons
• Different kinds of neurons perform
different functions
– Sensory neurons
– Interneurons
– Motor neurons
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
Interneuron
• Neuron that carries
nerve impulses from
one neuron to
another
• Can pass stimuli from
sensory neuron to
motor neuron
Motor Neuron
• Send an impulse to
a muscle and the
muscle contracts in
response
• Motor impulse
travels at 119 m/s
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
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
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
The Path of a Nerve Impulse
Reflex
• A reflex is an automatic response that
occurs very rapidly and without
conscious control
• Reflexes protect us from pain and
injury
Reflexes
Body systems that work with
the nervous system;
• The nervous system works with
every system in the body
Comparing Cells to the Body
• The cell part that controls the cell is the
nucleus