What makes you_nervous5
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Transcript of What makes you_nervous5
Lorem Ipsum
What Makes
You Nervous
Halloween Issue
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Nerve Impulses: Neurons are remarkable among cells
because they initiate and conduct signals called nerve impulse (1)
After cells go through a haunted house, they can have different nerve
impulse and reactions. Bellow you will find the different impulses.
Membrane Potential: All living cells,
including neurons, maintain a
difference in the concentration of
ions across their membranes. There is
a slight excess of negative ions on the
inside of the membrane. This results
in a difference in electrical charge
across their plasma membrane
(membrane potential) (1)
Resting Membrane
Potential: Electric charge
difference inside a cell
membrane, measured
relative to just outside the
cell membrane (2)
(2)
(2)
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Local Potential:
1. Stimulation of neuron by chemical, light, heat,
or mechanical distortion.
2. Stimulation alters permeability of various ions
thus leading to a change in resting membrane
potential. Increased Na+ permeability results in a
depolarization. Increased K+ or Cl- permeability
results in a hyperpolarization.
3. Local potentials are graded; that is, they vary in
magnitude.
4. Local potentials are decremental; that is they
get weaker the farther they spread from the point
of stimulation.
5. Local potentials are reversible. If the
stimulation ceases, the membrane potential drifts
back to resting membrane potential without
affecting the cell. (2)
Action Potential: Change in membrane potential
in an excitable tissue that acts as an electric signal
and is propagated in an all-or-none fashion. (2)
(2)
(2)
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Central Nervous System
The Central Nervous System, or CNS, is made up of
a person’s brain and spine.
This system is what allows the brain to communicate
with the body, and the body to give feedback to the brain
through the spinal cord.
This brain hat is a great way to show people that there is
a lot going on up there, and that your CNS is always in
action! (3 ©)
There are over 200 bones in the body, which
makes it easy to have several different bone candies by
the end of your trick-or-treating night.
If only they had different flavors! (4 ©)
The way that the brain communicates using the
spinal cords and nerves was by neurons. These are the
base of the Central Nervous System. Neurons are cells
that take and send out electrical signals to and from the
brain to the rest of the nerves, muscles, and body. (5 ©)
Peripheral Nervous System
Your brain tells your body that you want candy, but
the only way to get it is if your brain has a way to tell your
body where and how to get candy. That’s where the
peripheral nervous system kicks in!
The peripheral nervous system, also referred to as
PNS, is the pathway for nerve impulses from the central
nervous system to the rest of the body and is separated into
two parts; the somatic and automatic nervous systems. The
somatic nervous system controls the sensation as well as
movement while the automatic nervous system controls
organ function.
About.com Biology gives a brief outline of the main points
of the Peripheral Nervous System:
“• Sensory Nervous System - sends information to the CNS
from internal organs or from external stimuli.
• Motor Nervous System - carries information from the CNS to
organs, muscles, and glands.
• Somatic Nervous System - controls skeletal muscle as
well as external sensory organs.
•Autonomic Nervous System - controls involuntary
muscles, such as smooth and cardiac muscle.
•Sympathetic - controls activities that increase
energy expenditures.
•Parasympathetic - controls activities that
conserve energy expenditures” (6). (7 ©)
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Afferent and Efferent Divisions The nervous system is complicated. In order to explain the way things work,
scientists have come up with various terms that describe what they do and where
they go. The tissues of both the Central and the Peripheral nervous systems include
nerve cells that form pathways for stimuli to enter the nervous system and outgoing
pathways. The pathway through which stimuli comes into the body is called the
AFFERENT DIVISION. Afferent means “carry towards” the brain, which is the central
processing center of the body. The pathway through which the processed
information goes back out of the body and produces a response is called the
EFFERENT DIVISION of the nervous system. Efferent means “carry away” from the
brain.
Somatic and Autonomic Nervous Systems Another way to organize the components of the nervous system is to
categorize them according to the type of effectors they regulate.
The Somatic Nervous System (SNS) carries information (stimuli) to the somatic
effectors which are the skeletal muscles, or the muscles that control voluntary body
movement. These motor pathways make up the somatic motor division. The somatic
sensory division also includes the afferent pathways (or the incoming paths for
stimuli/signals.) The integrating centers that receive the sensory information
and generate the efferent response signal are also included in the SNS.
There is also an Autonomic Nervous System (ANS) which carries
information to the autonomic, or visceral, effectors which control the smooth
muscles, the cardiac muscle, and the glands; in other words, involuntary
reactions that are controlled by nerves in the ANS. (We now know that the
conscious mind can influence some of these functions but the traditional
name remains.)
The efferent pathways of the ANS are divided into the sympathetic and the
parasympathetic divisions. The sympathetic division of nerve fibers is made up
of pathways that exit from the middle portion of the spinal cord and produce
the “fight-or-flight” involuntary response to stimuli that threatens the body.
The parasympathetic pathways exit at the brain and the lower portion of the
spinal cord. They coordinate the body’s normal resting activities and are sometimes
called the “rest-and-repair” division and once again, they are INVOLUNTARY. The
ANS can be easily remembered by the “A” for “auto” as in automatic.
The afferent pathways (the ones that handle INCOMING stimuli) of the ANS belong
to the visceral sensory division which carries feedback information to the autonomic
integrating centers in the central nervous system.
Sources: Textbook Page: 344 & google.com©
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The Synapse
Summation
• Spatial summation: ability of the
postsynaptic neuron to add together the
inhibitory and stimulatory input received
from numerous different presynaptic
neurons and produce an action potential
based on that collation of info. (1)
• Temporal summation: when synaptic
knobs stimulate a postsynaptic neuron in
rapid succession and the effects add up
over time to produce an action potential.
(1)
Neurotransmitters
• Chemicals by which neurons
communicate; the substance is
released by a neuron, diffuses
across the synape, and binds to the
postsynaptic neuron. (1)
(1) (4)
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5 types of Glia and where to find them
1. Astrocytes- Wear a hat for a costume to show the astrocytes attached to
the outside of a capillary blood vessel in the brain. (1)
2. Microglia- Wear a shirt covered in small stationary cells to represent the
microglia being found in the central nervous system. (1)
3. Ependymal cells- Also another hat to wear representing the ependymal
cells forming a sheet that usually lines fluid cavities in the brain. (1)
4. Oligodendrocytes- Wear rows of oligodendrocytes hanging from your
clothes to show them lying clustered around nerve cell bodies; some are
arranged in rows between nerve fibers in the brain and cord. (1)
5. Schwann Cells- Bundle up wearing a lot of nerve fibers in the PNS,
wrapping around only the peripheral nerve fiber to form a thick myelin
sheath. (1)
Types of Neurons:
Multipolar costumes- have only one axon but several dendrites. The most
popular of the neurons costume are in the brain and spinal cord,
multipolar. (1)
Bipolar costumes- Have one axon and one highly branched dendrite. There
are the least amount of costumes available for bipolar. (1)
Unipolar costumes- Have a single process extending from the cell body.
This costume branches to form a central process and a peripheral process. (1)
Cells of the Nervous System Costumes: Cells of the nervous system costumes include
non-neural cells and neurons. Non-neural cells are neuroglia (meaning nerve glue), or glial cells, which support
and protect neurons and perform other functions, whereas neurons receive stimuli and conduct action
potentials. (2)
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Table 1
Table 2
Table 3
1. Voluntary movement is the conscious move that you must move. While involuntary
movement is a movement that you choose to move, like picking up a glass or running. Usually
voluntary movement is faster that involuntary.
2. 7.085 m/s
3. The difference could be due to the technology we used. Researchers most likely have more
precise instruments and testing methods which will lead to more accurate results.
4. The speed of electricity in a copper wire is 300 million, and the nerve impulse is 100m/s.
5. There can be a longer pathways the nerves may need to travel. Some peoples nervous
systems are slower or faster. Depends on the person. Muscle size does not have anything to
do with the speed of the nervous system.