Download NEURONS

NEURONS
NAME_______________________________
Period ________ Date _________________
Stimulus
<Notes #1- Nervous System>
_________________________- ( STIMULI - plural )- any change in the environment which
causes a response.
EX- light, gravity, food, etc.
*The ability to RESPOND to a stimulus is common to _______ living things !!!
all
Any
detected
Not all stimuli are
______________________
by the organism !! _____________
*________ change in the environment could be a stimulus ... as long as it is
detected!(You cannot detect things such as T V or radio waves, dog whistles, etc.)
nervous
*Most multicelled animals have a ___________________system that allows the
animal to detect and transfer information and quickly respond to stimuli.
There are three types of cells at work in a nervous system...for three different functions.
sense organs
neuron
2. One type of cell to TRANSFER the information..... the _____________________________
muscle or gland
3. One type of cell to RESPOND to the stimulus..... the ______________________________
1. One type of cell to RECEIVE the stimulus..... the _________________________________
Neurons
__________________________- a NERVE CELL...the basic unit of the nervous system.
Cell body
Dendrites
2. ___________________________- the branches that PICK UP the nerve impulse.
Axon
3. ___________________________the long cytoplasmic extension of the cell body; the nerve
1. ___________________________- the large part of the neuron that contains the nucleus.
impulse travels down this structure. Also known as the NERVE FIBER.
Myelin
Axon terminals the nerve impulse LEAVES the neuron here.
5. ___________________________Synapse
6. ___________________________the SPACE between two neurons; the nerve impulse must
4. ___________________________- the “insulation” that helps SPEED UP the nerve impulse.
cross/jump this space to continue on.
Nerve
__________________________- a bundle of neurons (a bundle of many nerve fibers)
It is similar to a telephone cable full of many separate telephone wires.
*** 1,000’s of neurons can make up one nerve !! ***
Nerve impulse
_______________________________ ( ” NI “ )- information from a stimulus that travels along
neurons (or nerve fibers).
90 m/sec
An impulse can travel up to ____________________________.
one
The NI travels in ________ direction along definite pathways.
D

axon

AT
D

axon
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AT
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D
axon
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AT
There are 3 types of NEURONS...
Sensory
1. ______________________ NEURON -
a neuron that carries impulses FROM sense organs TO the spinal cord or brain.
***these PICK UP the stimuli !
Motor
2. ______________________ NEURON -
a neuron that carries impulses FROM the spinal cord or brain TO a muscle or gland.
***these cause a RESPONSE to a stimulus !
Interneuron
3. ________________________________ - also called an Association neuron-
a neuron that carries impulses FROM sensory neurons TO the motor neurons.
***these are ONLY found in the SPINAL CORD or BRAIN !!!
Sensory
neuron
Motor
neuron
and
Interneuron
Reflex
One of the sim plest nerve im pulse pathw ays is called a _______________....
automatic
A REFLEX is an __________________________ response to a stimulus in which the
brain is NOT directly involved!
You are born with certain reflexes! A reflex happens so _____________ that you
quickly
after it happens!
do not think about them until ___________
*Reflexes you are aware of ... coughing, sneezing, blinking, pulling away from a hot object,
jumping when frightened, recovering your balance, etc.!
*Reflexes you are NOT aware of... release of digestive juices, movement
of the pupil of the eye, etc.!
*Reflexes happen so QUICKLY because the impulse must only travel
Spinal cord
TO and FROM the _____________________________ for the body to
react...remember, the brain is not directly involved in a reflex.
The brain will receive a message
AFTER/AS the reflex has occurred.
SIMPLE REFLEX ARC-
Sensory neuron
Spinal cord
Sense
organ
Muscle or
gland
Interneuron
Motor neuron
coordinating center
The SPINAL CORD acts as a “________________________________________________”.
It can make simple responses while it sends the information
think
to the BRAIN who will then _______________ about what has happened.
Receptors
_______________________________- special nerve ENDINGS that are sensitive
to SPECIFIC stimuli.
Examples of receptors-
The
eye (retina) is sensitive to LIGHT.
The
taste buds
on the tongue are sensitive to
CHEMICALS- sweet, salt, bitter, and sour.
The
inner ear (cochlea) is sensitive to SOUND WAVES.
The
nose (olfactory cells) is sensitive to
CHEMICALS- odors.
The skin is sensitive to
TOUCH, PRESSURE, PAIN, HEAT and COLD.