Information Can Control Behavior Without Creating A...

Information Can Control Behavior Without Creating A...
Bio Bases 1– Extra Credit Essay Questions – Exam 1 Erica Rodriguez 1. Visual information can
control behavior without creating a conscious sensation. Blindsight symptoms suggest that the belief
that "perception must enter consciousness to affect our behavior is not correct." There are many
mechanisms associated with vision one being the mammalian system that has direct connections
with sections of the brain accountable for consciousness. The mammalian system is the one that
gives us the ability to recognize the world surrounding us. The primitive system controls eye
movements focusing our attention to movements that are abrupt that happen outside of the field of
vision. When the mammalian visual system is damaged, people are able to use the primitive visual
system of the brain which helps guide hands over toward an object, even though they may not be
able to see it. The Blindsight proposes that consciousness is not a general property of all parts of the
brain. 2. Consciousness is a physiological function, such as behavior. Our self–awareness and ability
to communicate with one another through sending and receiving messages in a complex social
structure, giving us a great capability to learn. These abilities have evolved. 3. People who have
undergone split–brain surgery often say there left hand seems to have a mind of its own; such as
reading a book being held by the left hand and suddenly putting it down, not because of disinterest
but
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Action Potential Analysis
In our brain we have neurons that communicate every second of the day with one other through their
dendrite and axons. Most of the time incoming signals are received in the dendrites and outgoing
signals travel down the axon to the nerve terminal. For the neuron to receive the rapid
communication due to the long axon, the neuron sends electrical signals, from the cell's body to the
nerve terminal. This process is known as nerve impulses, or action potential. "Brain neurons can
transmit signals using a flow of sodium(Na+) and potassium (K+) ions, that produces an electrical
spike called an action potential (AP) (Forrest, 2014, P. 1). Action potential is essentially a slight
reversal of electric polarity across the membrane. When an action potential takes place, the sodium –
potassium pump resets the way sodium and potassium ions were back to their original positions. The
sodium–potassium does this to the neuron so when it is then ready to relay another action potential,
it will pump when called upon to do so. The Na+/K+ pump has a housekeeping role rather than a
direct role in brain signaling (Forrest, 2014, P. 1). For an action potential to be generated the
membrane voltage must be strong enough to bring the membrane voltage to a critical value called
the threshold. ... Show more content on Helpwriting.net ...
As the action potential is near its peak, sodium channels begin to close which then allows the
potassium channels to fully open. Potassium ions rush out of the cell and the voltage quickly returns
to its original resting state. This corresponds to the falling phase of the action potential. Sodium and
potassium at this point have switched places across the membrane and the resting membrane
potential is then slowly restored due to diffusion and the sodium–potassium pump. Without the
process of the sodium–potassium pump and the action potential, our nerve cells will not

action potential
The formation of an action potential can be divided into five steps. (1) A stimulus from a sensory
cell or another neuron causes the target cell to depolarize toward the threshold potential. (2) If the
threshold of excitation is reached, all Na+ channels open and the membrane depolarizes. (3) At the
peak action potential, K+ channels open and K+ begins to leave the cell. At the same time, Na+
channels close. (4) The membrane becomes hyperpolarized as K+ ions continue to leave the cell.
The hyperpolarized membrane is in a refractory period and cannot fire. (5) The K+ channels close
and the Na+/K+ transporter restores the resting potential. Action potentials are formed when a
stimulus causes the cell membrane to depolarize past ... Show more content on Helpwriting.net ...
Myelin and Propagation of the Action Potential For an action potential to communicate information
to another neuron, it must travel along the axon and reach the axon terminals where it can initiate
neurotransmitter release (Figure 2). The speed of conduction of an action potential along an axon is
influenced by both the diameter of the axon and the axon's resistance to current leak. Myelin acts as
an insulator that prevents current from leaving the axon, increasing the speed of action potential
conduction. Diseases like multiple sclerosis cause degeneration of the myelin, which slows action
potential conduction because axon areas are no longer insulated so the current leaks. A node of
Ranvier is a natural gap in the myelin sheath along the axon (Figure 3). These unmyelinated spaces
are about one micrometer long and contain voltage gated Na+ and K+ channels. The flow of ions
through these channels, particularly the Na+ channels, regenerates the action potential over and over
again along the axon. Action potential "jumps" from one node to the next in saltatory conduction. If
nodes of Ranvier were not present along an axon, the action potential would propagate very slowly;
Na+ and K+ channels would have to continuously regenerate action potentials at every point along
the axon. Nodes of Ranvier also save energy for the neuron since the channels only need to be
present at the nodes and not

Reflection Paper On Action Potentials
Thus far into my first semester of being admitted into the Respiratory program here at Wallace
community college, it has been a very hardcore, yet valuable learning experience. One that has
taught me many lessons but also helped me to grow into a better college student. There have been
many valuable and important lessons taught thus far into the program. But one that stood out to me
the most and one that I had the least amount of trouble with but was still yet challenging, was the
electrophysiology of the heart. In the beginning of the electrophysiology of the heart, it is taught that
the heart is contracted by a combination of generating and propagating action potentials. I have
learned that action potentials are electrical impulses that travel across the cell membranes in the
heart. These action potentials are one of many things that determines if the heart functions and quite
frankly if you live or not. According to Baylor Heart and Vascular Hospital, these contractions are
what triggers the events of an action potential which are also identical in skeletal muscles, cardiac
muscle, and neurons. To not get confused with the "triggering effect", but a transmitted action
potential is technically called a nerve impulse. An action potential isn't always in a constant state of
actively moving around, the "resting stage" or resting membrane potential as it should be referred to,
is the electrical difference between both electrolytes from the inside of the cell membrane

Diagnosis And Management Of Patients Suffering From...
Abstract
Neurophysiology provides a range of important clinical investigations to that aid in the diagnosis
and management of patients suffering from neurological disease. This experiment investigates the
mechanisms behind two pathologies pertaining to channelopathies and demyelination: epilepsy and
multiple sclerosis. This is done using a patch clamp technique, a laboratory technique in
electrophysiology that allows the study of single or multiple ion channels in cells. Conditions were
simulated using computer software to test the hypothesized mechanism behind epilepsy with
understanding that it was due to an increase in the time constant, which would enable frequent
neuron activations to occur simultaneously. Manipulations of stimulus impulse in refractory periods
had proven this mechanism to be correct. Investigating the basis for multiple sclerosis, it was
hypothesized that the cooling of impulse invasions would improve the demyelinated region of an
axon by decreasing voltage, which was found to be an accurate phenomenon.
Introduction
Neurophysiological Pathologies: Channelopathies Neurophysiology provides a range of important
clinical investigations to that aid in the diagnosis and management of patients suffering from
neurological disease. These investigations can be made using the patch clamp technique, a
laboratory technique in electrophysiology that allows the study of single or multiple ion channels in
cells. Information processing in the brain occurs

Action Potentials
In physiology, an action potential is a short–lasting event in which the electrical membrane potential
of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several
types of animal cells, called excitable cells, which include neurons, muscle cells, and endocrine
cells, as well as in some plant cells. In neurons, they play a central role in cell–to–cell
communication. In other types of cells, their main function is to activate intracellular processes. In
muscle cells, for example, an action potential is the first step in the chain of events leading to
contraction. In beta cells of the pancreas, they provoke release of insulin.[a] Action potentials in
neurons are also known as "nerve impulses" or "spikes", ... Show more content on Helpwriting.net
...
One type is generated by voltage–gated sodium channels, the other by voltage–gated calcium
channels. Sodium–based action potentials usually last for under one millisecond, whereas calcium–
based action potentials may last for 100 milliseconds or longer. In some types of neurons, slow
calcium spikes provide the driving force for a long burst of rapidly emitted sodium spikes. In
cardiac muscle cells, on the other hand, an initial fast sodium spike provides a "primer" to provoke
the rapid onset of a calcium spike, which then produces muscle

How Neurons Communicate And Fire Action Potentials
The topic we have learned thus far in lecture that has been the most interesting to me is how neurons
communicate and fire action potentials. I find it interesting, because this is the action that makes our
cognitions, thoughts, actions, feelings, etc. possible. Neurons sending and receiving messages, gives
us the ability to function properly and that is a big deal. I do have some background in Biology,
Physiology, and Anatomy so it was great to talk about this process in detail. The whole process of
firing action potentials was new to me, but the process of a post–synaptic neuron receiving an action
potential from a pre–synaptic neuron I had some previous knowledge about.
The process of firing an action potential happens in many steps and there are key players to the
process. On the cell membrane of the axon of a pre–synaptic neuron, specifically in the Nodes of
Ranvier, there are non–gated ion channels, voltage–gated ion channels, and ion pumps. All of these
are special proteins that are specific to ions and carry out specific functions. At resting membrane
potential, when an action potential is not being fired and the cell is at rest, there is Na2+ (sodium
ion) in high concentration outside the cell and K+ (potassium ion) in high concentration inside the
cell. Both are separated by a phospholipid bilayer that makes up the cell membrane and the cell is
slightly more negative inside the cell than outside the cell. At this time, sodium and potassium ions
are free to move

Action Potentials In A Giant Alga Lab Report
LAB #4: ACTION POTENTIALS IN A GIANT ALGAL CELL
Generating action potentials in a giant alga using mechanical stimulation, injury, or direct electrical
stimulation
Introduction The Chara coralline is a freshwater plant that lives in temperate zone ponds and lakes.
The intermodal segment is a single large cell which uses cytoplasmic streaming to distribute
organelles and nutrients throughout the cytoplasm which is surrounded by a large central vacuole.
Recording action potentials with intracellular microelectrodes is less complicated because Chara
cells are so large. Actin and myosin allow for the movement of intracellular materials. The Chara
coralline generates action potentials in response to deformation of the cell membrane. Then,
cytoplasmic streaming is halted via a signal that is spread by the action potential. Protein kinase is
activated due to the increase in internal calcium. The protein kinase phosphorylates myosin which in
turn inhibits its interaction with actin and terminates streaming. This allows a wound to heal without
leakage of the pressurized cytoplasmic contents.
The purpose of this lab is to examine the waveform characteristics of action potentials using
standard intracellular recording techniques. In the first set of experiments, students will use a glass
microelectrode to record from a giant algal cell. Then, students will generate an action potential in a
giant algal cell. If ion concentrations remain constant inside the cell, then the

Action Potential Research Paper
An action potential is the rapid depolarisation of the membrane potential to +40mV from its resting
potential of –70mV. The resting potential of a neuron is the difference in electrical voltage between
the inside and outside of the neuron's membrane.
An action potential is a short electrical impulse generated at the axon hillock which travels the
length of an axon. Its generation happens in three distinct stages, depolarisation, repolarisation and
hyperpolarisation. When the threshold of excitation is reached, depolarisation starts, the threshold is
between –55mV and –65mV in most neurons. When the neuron is stimulated voltage–activated
Sodium (Na+) channels open, allowing Na+ ions to rush into the neuron. This reverses the polarity
in the neuron towards its peak of +40mV. At this peak Na+ channels ... Show more content on
Helpwriting.net ...
In this stage, there are too many K+ ions outside the axon, causing the membrane potential to be too
low. The resting membrane potential is returned to –70mV after these ions diffuse.
The propagation of an action potential describes the movement of an action potential along an axon.
This is done through the regeneration of the action potential at different points as Na+ ions move
along the axon. The propagation of an action potential along a myelinated axon is quicker than in
unmyelinated axons. This is due to Saltatory conduction; where an action potential moves from one
node of Ranvier to another, along an axon. Saltatory conduction allows for faster and more efficient
propagation.
Two laws govern the generation and propagation of an action potential, the All–or–None Law and
the Rate Law. The All–or–None Law states that if an action potential occurs it will continue to the
terminal buttons without interruption. The Rate Law, however, describes how the different rates of
an action potential represent different stimulus

Examples Of Excitability
Rachel Lawton
9/7/2017
BIOL–2624–M01
Physiology Paper
Excitability is also called responsiveness. It has the ability to receive and respond to
stimulation by nerves and hormones, making it possible for the nervous system to regulate
muscle activity. Muscle excitability surrounds the number of muscle fibers during a contraction.
Some examples of excitable tissues are, cells, and cardiac and skeletal muscles. [1].
The sliding filament theory begins with the stimulation of a muscle. A nerve stimulates
an action potential to pass down a neuron to the neuromuscular junction. It then stimulates the
sarcoplasmic membrane to release calcium into the muscle cell. Calcium goes into the muscle
cell with troponin and allows actin and ... Show more content on Helpwriting.net ...
The ions involved are sodium and potassium. Sodium ions enter the cell,
and potassium ions leave.
[3].
An example of a disease that can affect skeletal muscles is fibromyalgia. Fibromyalgia is
a condition of muscle stiffness, soft tissue pain, fatigue, and disrupted sleep. Fibromyalgia is
associated with a wide spread amount of unexplained symptoms, some psychological depression,

and impairment of activities of daily living. Doctors do not know what causes fibromyalgia. [4].
Words Cited
[1]. Marieb, E. N, Keller, S. M. Essentials of human anatomy & physiology. NY, NY: Pearson. 2018,
Pg. 287–288
[2]. Teachpe: Home n.d. [Internet]. Available from:
http://www.teachpe.com/anatomy/sliding_filament.php [3]. Boundless: Stages of the Action
Potential [Internet]. Boundless Open Textbook: September 20, 2016. Available from:
https://www.boundless.com/psychology/textbooks/boundless–psychology–textbook/biological–
foundations–of–physhology–3/neurons–33/stages–of–the–action–potential–143–12678 [4]. Life
Extension: Fibromyalgia. [Internet]. Available

Autism: A Physiological Perspective Essay
Autism is a neural development disorder that affects a person's ability in socializing,
communicating, and repeating behaviors. In this paper, the working mechanism of neutrons is first
described and then the organization of the human brain is illustrated. Finally, autism is analyzed
with respect to its causes from bio–psychological perspectives.
Neuron Functions
Neurons are specialized cells that receive electrical inputs from other connected neurons and
transmit the electrical impulses to the next neuron through the mechanism of action potential.
Neurons have a special structure with a cell body (soma) that receives inputs from highly branched
dendrites in the form of electrical impulses and transmit action potential through axon. ... Show
more content on Helpwriting.net ...
The synapse has two neurons: pre–synaptic that sends and post–synaptic that receives information.
When an action potential arrives at a synapse, pores in the cell membrane begin to open such that
calcium ions can flow into the pre–synaptic terminal, causing chemical neurotransmitters to be
discharged into the synaptic cleft. The neurotransmitter spread over the synaptic cleft and interacts
with receptors in the post–synaptic membrane. These receptors are ion channels and will open up to
let ions flow into the post–synaptic terminal after they interact with the neurotransmitter.
Neurotransmission can be either excitatory or inhibitory, which either increases the likelihood of the
post–synaptic neuron triggering an action potential or decreases that of an action potential being
generated. The production of action potentials follows the all–or–nothing principle because they
either occur completely or do not happen at all.
Brain Organization
Located in the medial temporal lobe of the brain, hippocampus plays a critical role in allowing
people to consolidate recent information and events.
Deep in the medial temporal lobes of the brain in complex vertebrates, amygdala is responsible for
processing and memorizing emotional responses.
Cerebral cortex is a thin layer of gray tissue on the surface of the central brain hemisphere. About
two thirds of this

Action Potential Essay
RESTING POTENTIAL
Resting potential is the membrane potential when a neuron is not conducting any electrical impulse
or signal. The resting potential is around –75 mV. During resting potential, the inside of the axon is
negative
GRADED POTENTIAL
ACTION POTENTIAL
Action potential is a fleeting reversal of the membrane potential, caused by changes in permeability
of the plasma membrane of neuron to potassium and sodium ions causing an electrical impulse to be
transmitted along the axon.
When a stimulus depolarizes the membrane, a few of the voltage–gated sodium channels that are
found in the neuronal plasma membrane open permitting sodium ions to pass through. Since there is
much greater concentration of sodium ions outside the ... Show more content on Helpwriting.net ...
This is called temporary hyperpolarisation. The potassium channels then close, and the sodium–
potassium pump begin to act again, restoring the normal/original distribution of sodium and
potassium ions across the membrane, and therefore restoring the resting potential. This process takes
time. THE REFRACTORY PERIOD Refractory period is the period of time during which a neuron
is recovering from an action potential, and during which another action potential cannot be
generated. At this period, the voltage–gated sodium channels are still firmly closed (or temporary
inactivated) and the membrane cannot produce an action potential, regardless of the stimulation.
CONDUCTION/PROPAGATION/TRANSMISSION OF ACTION POTENTIAL An action
potential at any point along an axon's plasma membrane triggers the production of an action
potential in the membrane on either side of it. During the action potential, sodium ions enter a point
on the axon. The temporary depolarization of the membrane where the action potential is causes a
'local circuit' to be set between the depolarized region and the resting regions on either side of it.
Sodium ions flow sideways inside the axon, away from the positively charged region towards the
negatively charged regions on either side. This depolarizes these adjoining regions and so generates
During the action potential, sodium ions enter

Frog Nerve
1. How does a CAP differ from a single action potential?
Single action potentials follow the "all or none" rule. The "all or none" rule being that if a stimulus
is strong enough to depolarize the membrane of the neuron to threshold, then an action potential will
be fired. Each stimulus that reaches threshold will produce an action potential that is equal in
magnitude to every other action potential for the neuron. Compound action potentials do not exhibit
this property since they are a bundle of neurons and have different magnitudes of action potentials.
Compound action potentials are also graded, meaning the greater the stimulus, the greater the action
potential. 2. Action potentials are said to be all or none responses. Why does ... Show more content
on Helpwriting.net ...
As you increase the amplitude, more neurons reach their threshold and contribute to the increase in
size of the compound action potential (CAP). Eventually, as the stimulus voltage is increased, a
point will be reached when the waveform of the action potential stops changing. At this point all the
fibers in the nerve able to respond to the stimulus are stimulated, which is the maximal response. 4.
In this exercise, you examined the effect of increasing stimulus intensity on the nerve. What other
stimulus parameter might also affect the nerve's tendency to generate a CAP? 4. In this exercise, you
examined the effect of increasing stimulus intensity on the nerve. What other stimulus parameter
might also affect the nerve's tendency to generate a CAP?
Frequency and duration can also affect the nerve's tendency to generate CAP's. Frequency can affect
it because if there is the right amount of time between them, their effects can be added and trigger a
CAP. Durations can affect it because even a weak stimulus can potentially trigger a CAP if kept up
long enough.
Exercise 2: Refractory Period 5. Explain the difference between the relative and absolute refractory
periods.
During an absolute refractory period, a second stimulus will not produce a second action potential
no matter how strong the stimulus is. Absolute refractory period corresponds to the period when
Na+ channels are open (often just a millisecond or less). During a relative refractory period,

Lab Report- Neurophysiology of Nerve Impulses Essay
Introduction Neurons (also known as neurons, nerve cells and nerve fibers) are electrically excitable
and the most important cells in the nervous system that functions to process and transmit
information. Neurons have a large number of extensions called dendrites. They often look likes
branches or spikes extending out from the cell body. It is primarily the surfaces of the dendrites that
receive chemical messages from other neurons. One extension is different from all the others, and is
called the axon. Although in some neurons, it is hard to distinguish from the dendrites, in others it is
easily distinguished by its length. The purpose of the axon is to transmit an electro–chemical signal
to other neurons, sometimes over a ... Show more content on Helpwriting.net ...
When a membrane is excited depolarization begins. When the membrane depolarizes the resting
membrane potential of –70 mV becomes less negative. When the membrane potential reaches 0 mV,
indicating there is no charge difference across the membrane. the sodium ion channels start to close
and potassium ion channels open. By the time the sodium ion channels finally close. The membrane
potential has reached +35 mV. The opening of the potassium channels allows K+ to flow out of the
cell down its electrochemical gradient ( ion of like charge are repelled from each other). The flow of
K+ out of the cell causes the membrane potential to move in a negative direction. This is referred to
as repolarization. ( Marieb & Mitchell, 2009). As the transmembrane potential comes back down
towards its resting potential level and the potassium channels begins to close, the trasmembrane
potential level goes just below –90mV, causing a brief period of hyperpolarization (Martini, Nath &
Bartholomew, 2012). Finally, as the potassium channels close, the membrane turns back to its
resting potential until it is excited or inhibited again. In this experiment we will be dealing with two
chemicals that intend to inhibit a nerve impulse. Curare is a toxic substance that interferes with the
neural transmission between motor neurons and skeletal muscles. Curare competes with
acetylcholine –or Ach– for receptors on muscle cells. Acetylcholine is a chemical

Frog Nerve
Frog Nerve
Exercise 1: Action Potential Threshold
Using the Horizontal Compression buttons and the scroll bar display the data you wish to include in
your report.
Study Questions 1. How does a CAP differ from a single action potential? 1. How does a CAP differ
from a single action potential?
Answer
CAP or compound action potential is a measure of the sum of the "all or none" single action
potential of a group of fibers in a single nerve. The single action potentials are events that occur
when sodium channels are activated causing the depolarization of a neuron. Single Action potentials
are considered to be all or none responses, they travel down the length of the axon and then release a
neurotransmitter into the synapse. ... Show more content on Helpwriting.net ...
This means that at a lower voltage only the larger diameter axons will be stimulated and elicit a
smaller response however, at higher voltages even the smaller axons will be stimulated and elicit a
response. So because there are a collection of different neurons with varying sizes only some will be
activated at lower voltages and as the voltage increases so will the amount of neurons which
produce action potentials therefore raising the total response and giving the "graded" response
observed. 3. What was the smallest voltage required to produce the maximum (largest) CAP? What
proportion of the nerve fibers were excited to produce this maximal response? 3. What was the
smallest voltage required to produce the maximum (largest) CAP? What proportion of the nerve
fibers were excited to produce this maximal response?
Answer
The smallest voltage required to produce the maximum CAP was 300 mV. In order to produce the
maximal response in theory all of the nerve fibers would need to be excited because as the answer
given above noted the graded response of the sciatic nerve would increase until all of the nerve
fibers have been excited and then it would hit maximal CAP because at a voltage of 300 mV all
nerve fibers would be excited and no further action potentials could arise. 4. In this exercise, you
examined the effect of increasing stimulus intensity on the nerve. What other stimulus parameter

Action Potential Lab Report
Action potential is comprised of 5 distinct phases which are resting state, depolarization, rising
phase, the falling phase and the undershoot. The resting phase happens when the cells are dormant,
and all sodium and potassium channels are closed.
Depolarization happens when a stimulus is applied and will cause the ligand gated sodium channel
to undergo a conformation change which allows the ion channel to open and sodium can now pass
through the sodium potential into the cell. The potassium channel is still closed. There must be a
enough change in potential in order to allow depolarization to occur (also known as threshold
potential). If there is enough, the cell will completely depolarize, if not then it will return to rest and
nothing will occur, which is known as the "all or nothing principle".
When the cell has reached the threshold potential, the rising phase occurs. Th sodium channels open
and allow a large quantity of sodium into the cell, which will drive the membrane potential to be
positive. This will cause the cell to change from negative to positive in respective to the outside of
the cell. Once the cell becomes positive, the sodium channel will be plugged, and sodium will stop
entering the cell.
Now that the inside of the cell is positive, potassium ions will now flow out ... Show more content
on Helpwriting.net ...
Since our concentration of sodium inside the cell is greater than the concentration of sodium outside
the cell, there was not much action potential because sodium was not trying to enter the cell but
leave the cell. The reason was because the cell was trying to reach homeostasis and more sodium
will go from the inside to the environment (https://www.biology). Sodium plays an important role in
action potential as it will determine the action potential entering the

Final Exam Questions On Osmosis
Michelle Leeman Final Exam: 1) Fill in the blanks using the appropriate directional term: (in the
anatomical position) (5 pts) a) The heart is posterior to the sternum b) The manubrium is medial to
the gleno–humeral joint c) The dura mater is anterior to the spinal cord d) The cranium is superior to
the sacrum e) The calcaneus is posterior to the toes 2) What is osmosis? Is osmosis a passive or an
active process? Describe how osmosis occurs across the cell membrane. How can the solute
concentration of the interstitial fluid affect cell shape? Be specific. (5 points) Osmosis is the
movement of water molecules through a semi–permeable membrane into a region of higher solute
concentration to equalize the solute concentrations on both sides. Osmosis is a passive process and
does not require energy like an active process would. A semi–permeable membrane is a membrane
that allows certain molecules or ions to pass through, water being one of those molecules, thus
allowing water to freely flow in and out of a cell. The cell must have equal concentrations on either
side of the membrane to allow it to function, therefore water will pass in and out of the cell to
equalize the concentration of ions of both sides. Solutions of different concentrations will pass water
from the side with lower concentration to the side with higher concentration, thus changing the cell's
shape. A cell that is placed in a hypertonic solution (solution concentration that is lower than cell's

Peripheral Nervous System Essay
1. Describe the basic functions of the frontal, temporal, parietal, and occipital lobe.
Frontal lobe is responsible for mental functions such as planning, language, and decision making.
The temporal lobe is responsible in understanding language. The parietal lobe is responsible for our
sense of touch, temperature and body position. The occipital lobe is responsible for vision.
1. Distinguish between the central nervous system and the peripheral nervous system.
The central nervous system (CNS) consists of the brain and spinal cord. It sends information to (and
receives information from) the peripheral nervous system (PNS), which consists of all of the nerves
that lie outside the CNS. The PNS collects information about the environment, sends it to the CNS
and transports output from the CNS to ... Show more content on Helpwriting.net ...
During the second half of an action potential the sodium channels close, potassium channels open,
potassium diffuses out of the neuron, and the membrane repolarizes.
4. Describe the functions of neuroglial cells.
Neuroglial cells provide physical support and protection to neurons. In the peripheral nervous
system, neuroglial cells called Schwann cells produce a lipoprotein called myelin which insulates
the neuron, speeds up the transmission of impulses, and assists in axonal regeneration in the event of
an injury. Neuroglial cells of the central nervous system are called oligodendrocytes.
Oligodendrocytes also provide myelin, to insulate neurons and speed up transmission of impulses,
but oligodendrocytes do not assist in regeneration.
5. Describe the role of neurotransmitters in the function of neurons.
Neurotransmitters are required for an action potential in one cell to be transmitted to another cell.
They are chemicals that are released by a neuron, diffuse across the synaptic gap, and attach to
binding sites on the post synaptic

Explain The Mechanisms Of Neural Communication, And The...
The purpose of this essay is to explain the mechanisms of neural communication, and the influence
that different drugs have on this communication. The nervous system is made up of several cells that
are called neurons, which are situated inside the Central Nervous System (Martin, Carlson & Buskit,
2013). Neurons comprise of three mechanisms, a cell body which is referred to as the soma,
dendrites and an axon (Pinel, 2011). The cell body comprises of the nucleus and other organelles
(Ward, 2010). The nucleus contains the genetic code, and this is involved with protein synthesis (He,
2013). The dendrites receive information from other neurons which are located in a close proximity
(Kalat, 1995). The terminal of an axon compresses into a disc–shaped structure (Gross, 2010). This
is where chemical signals also known as a neurotransmitter permit interaction amongst neurons, by
means of a minute gap named a synapse (Martin, Carlson & Buskit, 2013). Both neurons which
form the synapse are referred to as a presynaptic synapse (prior to the synapse) and postsynaptic
(after the synapse), reflecting the direction of information flow (from axon to dendrite), (He, 2013).
Once a presynaptic neuron is passive, an electrical current is spread along the length of the axon
(Schiff, 2012). This is known as action potential (Pinel, 2011). Action potential happens once an
abundant amount of depolarisation reaches the limit through the entry of sodium, by means of
voltage gated sodium channels

Neur's Resting Membrane Potential
The neuron's resting membrane potential is usually –70 millivolts. This charge comes from the fact
that there are more negatively charged sodium ions outside the cell than there are positive potassium
ions inside the cell. These ions are arranged by the sodium–potassium pump: for every 2 potassium
ions it pumps into the cell, it pumps out 3 sodium ions. The membrane is also riddled with ion
channels, large proteins that provide passage when their respective gates open. Most are voltage–
gated channels, which open or close at certain membrane potentials. Ligand gated channels that only
open when a specific neurotransmitter or hormone attaches to it. Finally, mechanically gated
channels open in response to physically stretching the membrane. When the gates open, ions diffuse
across that membrane down the electro–potential gradient. ... Show more content on Helpwriting.net
...
The dendrites pick up the signal and activate the neuron's action potential that shoots an electric
charge down the axon to its terminals and towards neighboring neurons. Neurotransmitters are
stored in vesicles inside the terminal button of the axon; the vesicles are transported to the edge of
the button and the neurotransmitters released into the synaptic gap. In the synapse, neurotransmitters
can bind with a receptor site on the next neuron if the receptor site is the right type and is vacant.
This is often described by a lock and key analogy, in that the neurotransmitters (like keys) can only
fit into certain receptor sites (like

How Does The Structure Of Neurones Reflect Their Function?
How does the structure of neurones reflect their function?
The brain is a unique organ, it allows us as humans, for example to imagine, speak and perform a lot
more complex functions. To function well as a complex organ, the brain has a lot of cells. The brain
consists of neurones and glia cells. Neurones observe changes from the environment, communicate
these changes to other neurones and issue commands to the body to react on these changes. Glia
cells give the neurones among other things protection and support. Neurones are really small cells
composed of two parts: the soma, which contain the cell nucleus and neurites, which are projections
from the soma. There are two different types of neurites, the axon and the dendrite. Dendrites
receive signals to transfer to the neurones and axons carry the output of the neurones. Figure 1 gives
a schematic overview of a neuron and shows the dendrites, cell body and axon. This essay will
discuss the structure of neurones and the different types of neurones further in detail. It will start
with the structure of a typical structure of a neuron and then the different types of neurones, the
sensory–, motor– and interneurones. (Bear, M.F. et al. (2007))
Figure 1: Schematic view of the structure of a neuron (Anon. (undated))
A neuron contains as mentioned above dendrites. Through many dendrites, the neuron receives
signals from other neurones. The neuron passes this signal on, by most of the time one axon. This
axon can travel a long,

Outline The Processes Of Nociception
Week 7 FPP Assignment
Kelsy Weavil
Q1. (1a) Outline the processes of nociception:
Nociception is a neural process that senses and responds to harmful stimuli, for instance in this
scenario Linda rolling her ankle. Nociceptive pain comes from an actual or potential mechanical or
chemical stimuli that causes injury to non–neural tissue, this is due to the activation of nociceptors.
(1)
Nociceptive pain has 5 phases: Transduction, Conduction, Transmission, Modulation, and
Perception.
Transduction occurs under the skin, within joints or organs where nociceptors (sensory neurons) are
activated when the sensory receptor of the peripheral somatosensory nervous system reaches a high
threshold. When the body is struck by a harmful stimulus that is damaging or threatening a tissue it
creates an action potential by two types of nociceptor fibre, A–delta fibres and C–fibres. (2) In this
example, the harmful stimulus is Linda rolling her ankle. This has activated her sensory receptors as
her maximum threshold potential was reached therefore initiating the transduction phase.
Conduction occurs when that action potential transmits along the periphery up to the cell bodies in
the dorsal root ganglion in the spinal cord. (2) The action potential from Linda's ankle injury is
travelling up the periphery via the primary afferent nociceptor.
Transmission occurs when the action potential reaches the presynaptic terminal in the dorsal horn of
the spinal cord. A–delta and C fibres release

Action Potential Essay
Question 1
The action potential occurs in the space between the myelinated sections of the axon. The diffusion
and electrostatic pressure pushes sodium ion Na+ into the cell despite the lack of permeability of the
membrane. The cell uses sodium–potassium transporters to pump out three Na+ and pump in two
potassium ions K+ resulting in a low intracellular levels of Na+. this creates a voltage difference of
–70mv which is the neurons resting potential. When the neuron is stimulated by a presynaptic
neuron the sodium channels open, letting in positive sodium ions in. this changes the electrical
environment inside the cell more positive than the outside. This process is called depolarization, and
it causes a chain reaction with the rest of the ... Show more content on Helpwriting.net ...
The sympathetic division controls the disbursement of energy from reserves in the body. The
parasympathetic division controls the storing of energy during a relaxed state. The sympathetic
fibers originate in the thoracic and lumbar regions of the spinal cord The parasympathetic fibers
originate cranial and sacral region. Both divisions require efferent preganglionic neurons and
postganglionic neurons, whose synapsis housed in ganglia. Sympathetic ganglia are located close to
the spin and can send out signals far and wide to the surrounding organs. Parasympathetic ganglia
are located further from the spinal cord and closer to the organs that they operate with.
Question 4 The book mentions peripheral ganglia primary part of the peripheral nervous system. It
also mentions basal ganglia are the nuclei in the telencephalon, caudate nucleus, globus pallidus,
and the putamen all significant to the motor system. Sympathetic ganglia are located close to the
vertebral column and are part of the sympathetic branch of the autonomic nervous system.
Parasympathetic ganglia are located adjacent to the organs that they operate with and are part of the
parasympathetic branch of the autonomic system. Dorsal root ganglia bring rise to somatosensory
information to the spinal cord.
Question

Multiple Sclerosis Case Study
The peak of the CAP changes with different strength stimulus because the sizes and thresholds of
the nerve fibres within the nerve is different. Larger nerve fibres have lower threshold stimuli than
smaller ones, hence larger fibres were activated first, followed by smaller ones. As stimulus strength
increased, the larger nerve fibres began firing followed by the activation of the smaller ones (refer to
Figure 2). At the maximal stimulus a constant pattern was formed. This was because all the nerve
fibres were now firing and there were no further fibres to be activated.
Reductions in temperature lengthen the compound action potential and this is due to the affects in
refractory period.
The refractory period is affected largely due to the temperature because as the nerves are cooled, the
absolute refractory period is prolonged. Generally, during the absolute refractory period, the sodium
channels are opening or recovering, and the second action potential cannot be initiated during this
period. ... Show more content on Helpwriting.net ...
Disrupted nerve signals cause the symptoms of MS, which vary from one person to another and over
time for any given individual, depending on where the damage occurs. Heat or humidity can make
patients with MS experiences temporary worsening of their symptoms. This is because the heat
cause the nerves, (whose myelin covering has been destroyed from MS) to conduct electrical signals
even less efficiently. By decreasing the temperature, the duration of the action potential is increased
and therefore the electrical signal will be sent more faster and unlikely to be interrupted along the
axon. Therefore, decreasing body temperature would decrease the severity of the symptoms of MS,
helping the patient to function more

The Importance Of Multiple Sclerosis
Multiple sclerosis is an unpredictable, mostly paralyzing disease of the central nervous system that
inhibits the flow of information inside the brain, and between the brain and body.
The myelin sheath is sort of a conductive blanket around nerves which assists nerve impulses and
messages travel fast and effectively, it is made up of protein and fatty substances. Usually the
myelin sheath is used to keep a fast pace up nerve cell transmission from the brain and spinal cord.
The nodes of ranvier are constrictions in the myelin sheath that border the axons of nerve cells, or
neurons. They happen about one millimetre intervals along the body of the axon. There must be
breaks in the myelin to conduct electricity in neurons. These spaces are ... Show more content on
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How multiple sclerosis works is that white cells puncture the blood–brain barrier and they infiltrate
the central nervous system. These white cells then damage/harm the myelin sheath that safeguards
the nerve fibers which then forms lesions. More white cells will then appear from being drawn by
chemical messages from the beginning white cells. Repair and scarring follow from the
inflammation but some myelin will be permanently damaged. Impulses will then travel along the
damaged nerves very poorly/slowly. In extreme cases nerve impulses don't travel at

The Membrane Potential Between Outside And The Inside Cell...
Option 2:
The resting membrane potential is the difference between the outside and the inside cell membrane
polarity. It is called a resting potential because it occurs when a membrane is not being stimulated or
conducting impulses (Ritchison n.d.). This polarity can be measured and it is about –70mv. In the
resting membrane potential, outside the cell has a more positive polarity and inside the cell has more
negative polarity. There are more Na+ and Cl– on the outside and larger negative proteins (because
they cannot go through the tiny pores to outside) and more K+ inside the cell (Ceballos, 2016).
Diffusion, electrostatic pressure, and sodium–potassium pump are the main forces affecting the
resting membrane potential. Diffusion and electrostatic pressure work against the resting membrane
potential and sodium–potassium pump help the resting potential. Diffusion occurs if there is a
concentration gradient present and the molecules move from the higher concentration to the lower
concentration.
Electrostatic pressure work as simple as a magnetic effect, which is characterized by the opposite
attraction of. Sodium–Potassium pump is an active mechanism and need energy (by food etc.) to
work. In this case, 3 Na+ ions are excluded to the outside of the cell and 2 K+ ions brought into to
the cell. This energy supply occurs through food we eat and they break ATP (Adenosine
Triphosphate) to ADP (Adenosine Diphosphate). In action potential, only axon depolarization
occurs, not to

What Role Do Neurons Play In Psychology
Please compose an essay (one page) that answers the following questions: 1) How does a neuron
work? 2) Why does it matter that I know how a neuron works in a course about Psychology?, and 3)
What role do neurotransmitters play in Psychology? Here are some web sites that may additionally
help you with this assignment
Our human brains have about 100 billion neurons. These neurons react to physical and chemical
changes in their surroundings. These cells specialize in sending and receiving neural messages.
These neurons make connection with other neurons and send signals all over our bodies. Typically
every neuron has a cell body, dendrites and an axon. Neuron's body cell is like many other cells in
body comprising of cytoplasm, nucleus, mitochondria, lysosomes, Golgi apparatus and many
microtubules. These organelles enable to cell to perform its function. The axon portion of the neuron
is responsible for carrying information to other neurons. The dendrite portion of the neuron is
responsible for receiving the signals from the other neurons. Although neuron may have many
dendrites, they typically have only one axon. All neurons are electrically excitable, maintaining
voltage gradients across their membranes by means of metabolically driven ion pumps, which
combine with ion channels embedded in the membrane to generate intracellular–versus–
extracellular concentration differences of ions such as sodium, potassium, chloride, and calcium.
Changes in the cross–membrane voltage can

Essay on Physioex 9.0 Exercise 3
Activity 1
1. Increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+ leak
channels because the membrane is permeable to K+ ions. Therefore, the K+ ions will diffuse down
its concentration gradient from a region of higher concentration to a region of lower concentration.
2. Increasing extracellular K+ causes the membrane potential to change to a less negative value
because the K+ ions diffuse out across the membrane. My results went well compared to my
prediction because I predicted that the resting membrane potential would become less negative.
3. The extracellular Na+ did not alter the membrane potential in the resting neuron because the Na+
channels were mostly closed.
4. Na+ and K+ both have a ... Show more content on Helpwriting.net ...
5. The Pacinian corpuscle and free nerve ending will likely not have a membrane protein that
recognizes other molecules because their stimulus modality are not chemical unlike the olfactory
receptors.
6. The type of sensory neuron that would like respond to a green light would be photoreceptors.
Activity 3
1. The term threshold as it applies to an action potential is the voltage at which you first observe an
action potential.
2. Depolarization in membrane potential triggers an action potential because nearby axonal
membranes will be depolarized to values near or above threshold voltage.
3. The action potential at R1 (or R2) stayed the same as I increased the stimulus above the threshold
voltage. My results did not compare well with my prediction because I predicted that the peak value
of the action potential would increase.
4. The phrase "all–or–nothing" describes action potential because it only occurs when you reach
threshold voltage.
5. The part of the neuron that was investigated in this activity was the axon.
Activity 4
1. TTX blocks the voltage–gated Na+ channels between R1 and R2, which blocks the propagation
of the action potential from R1 to R2.
2. Lidocaine blocks the voltage–gated Na+ channels between R1 and R2, which blocks the
propagation of the action potential from R1 to R2. The effect of lidocaine differs

Action Potentials And Its Effects On The Body
Neurons are specialized cells that communicate through electrical signals throughout the body.
Nerves are made up of neurons and are made of bundles of nerve fibers. In previous experiments,
action potentials were observed. Action potentials are an all or nothing response and do not
deteriorate as it travels down the length of the nerve. Action potentials are directed by voltage–gate
pumps. One type of action potential is a compound action potential (CAP). CAP is an artificial
response of a nerve when all the axons are simultaneously electrical stimulated. It is known that
individual action potentials are voltage–dependent therefore it elicits an all–or–nothing response, but
CAP are graded potentials. The amplitude of the CAP increases as the stimulus voltage increases.
Each axon has its own threshold, so as the stimulus voltage increases it integrates more axons thus
creating a larger response.
For the experiment the sciatic nerve of an African Clawed Frog was examined. The sciatic nerve
was used because it is the largest nerve in the body. The specimen was used because frogs are active
animals with a large and testable sciatic nerve. By using the sciatic nerve, the threshold voltage,
conduction velocity, strength–duration curves, refractory periods, and monophasic action potential
can be determined and examined. The experiment should provide a better understanding of
compound action potentials. The overall purpose of the experiment was to test the effects of the
stimulus

8 Factors That Can Influence The Potential On Postsynaptic...
1. The following are 8 factors that can influence the potential on the postsynaptic membrane:
(a) Excitatory Postsynaptic Potentials (EPSPs): EPSPs increase the postsynaptic neuron's likelihood
to generate an action potential by generating a local depolarization. EPSPs result from excitatory
stimuli, such as an excitatory neurotransmitter (Glutamate) released by the presynaptic neuron.
Excitatory stimuli will bind and open ligand–gated Na+ channels, allowing Na+ ions to move inside
a cell down their concentration gradient. The influx of Na+ ions will cause a local depolarization at
the postsynaptic membrane, which if summated can reach threshold and fire an action potential.
(b) Inhibitory Postsynaptic Potentials (IPSPs): EPSPs decrease the postsynaptic neuron's likelihood
to generate an action potential by generating a local hyperpolarization. EPSPs result from inhibitory
stimuli such as an inhibitory neurotransmitter (GABA) released by the presynaptic neuron.
Inhibitory stimuli can bind and open ligand–gated K+ channels and Cl– channels, allowing K+ ions
to move out of a cell and allowing Cl– ions to move into a cell down their concentration gradient.
The influx of Cl– ions and the outflux of K+ ions causes a local hyperpolarization at the
postsynaptic membrane, which reduces the postsynaptic neuron's probability to firing an action
potential.
(c) Temporal Summation: The presynaptic neuron can influence the postsynaptic neuron by
changing the frequency of the stimulus.

Epilepsy Is A Central Nervous System Disorder ( Cns )
Introduction
Epilepsy is a central nervous system disorder(CNS) causing recurrent seizures and can only be
defined when there is at least one epileptic seizure.[1][2] John Hughlings Jackson, a notable British
neurologist proposed that epilepsy is "an occasional, an excessive and a disorderly discharge of
nervous tissue". About 65 million people(1% of the human population) in the world have epilepsy
and the cases account for 80% in developing countries. [3][4] In this essay, the normal physiology of
nerve transmission in cerebral cortex and pathophysiology of epilepsy will be discussed. The
mechanism of action of valproate is also studied and how it leads to the treatment of epilepsy.
Normal Physiology of Nerve Tranmission in Cerebral Cortex
The body system that is affected by epilepsy is CNS which is consisted of the brain and the spinal
cord.[5] (Figure 1) Figure 1 The major divsions of CNS[5]
The brain has a part called the cerebral cortex(gray matter) which is made up of 3 to 6 layers of
neurons.[7] A neuron has three parts namely axon, dendrites and cell body.[6] Neurons are classified
as principal(projection) neurons and interneurons. Principal neurons transmit information to other
neurons in the brain and form excitatory synapses. Interneurons in the CNS transmit impulses
locally and form inhibitory synapse.[7] Two common types of pathways for these neurons include
recurrent feedback pathways and feed–forward pathways.[9](Figure 2) `

What Is Neuromuscular Junction?
A neuromuscular junction is a chemical conjunction formed during the contact between motor
neuron and a muscle fiber. Each branch of a motoneuron forms a single junction with a muscle fiber
(University of Minnesota, 2011). At the neuromuscular junction, the motor neuron is able to send a
signal to the muscle fiber which ultimately allows for muscle contraction. The operation, when the
neurotransmitter, are released by a neuron begins when the action potential reaches the presynaptic
terminal of the neuron, which then activates calcium channels allowing calcium ions to enter the
neurons. The calcium ions that entered the neuron then bind to a sensory protein like synaptotagmin,
releasing vesicle fusion across the cell membrane. Vesicles are ... Show more content on
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As Lyn D. Weiss et al. (2016) states in Easy EMG: A Guide to Performing Nerve Conduction
Studies and Electromyography, the neuromuscular junction is the relay between the nerve terminal
and the skeletal muscle fiber. The neuromuscular junction as a whole is the site where the neurons
activate the muscle to actually contract. The steps of the neuromuscular junction are supposed to
happen quickly and accurately while ensuring voluntary movement of the muscles. The reliability of
transmission is aided by specialized architecture (multiple active zones, junctional folds), which has
been all studied more closely throughout the last century (Hong and Etherington, 2011). According
to "Annual Review of Neuroscience," the NMJ forms in a series of steps that involve the exchange
of signals amid its three important cellular components–nerve terminal, muscle fiber, and Schwann
cell (Cowan, 1999). All three cells of the neuromuscular junction travel long distances to meet at the
synapse(Cowan,

Accelerated Sensor Of Action Potentials
Accelerated Sensor of Action Potentials 1 The authors were trying to achieve a goal that they
describe as a major goal in the field of neuroscience. They were looking for some method of
reporting electrical activity in neuronal populations, specifically optical reporting. They developed a
voltage sensor that they named Accelerated Sensor of Action Potentials 1 or ASAP1. This allows for
GFP to be inserted into an extracellular loop of a voltage–sensing domain (VSD) and making
fluorescence responsive to membrane potentials. They were looking for ASAP1 to detect a broad
spectrum of membrane potentials, ranging from subthreshold to rapid trains of action potentials. For
this to be the case they had to have the appropriate brightness, dynamic range and kinetics. They
hypothesized that inserting GFP into the S3–S4 loop would allow voltage–induced movements to
interrupt GFP fluorescence. They also hypothesized that a VSD with a shorter loop would increase
the coupling between the voltage–induced movements and GFP barrel distortions. They performed
various tests and concluded that a particular variant of the GFP improved brightness, dynamic range
and expression at the membrane, giving rise to the protein they named ASAP1. From here they
performed tests to show that the VSD that they chose initially was the best choice. There are many
methods that were used in the achieving of this goal. Plasmids are small circular sections of double
stranded DNA that are distinct from a cells

The Parameter Extraction For Neuron Model Simulation Of...
Parameter Extraction for Neuron Model Simulation of Action Potential in Earthworm giant nerve
fiber
Rashmi Deka
Department of Electronics and Communication Engg.
Tezpur University
Tezpur, Assam, India
Email: rashmee@tezu.ernet.in
Jiten Ch. Dutta
Department of Electronics and Communication Engg.
Tezpur University
Tezpur, Assam, India
Email: jitend@tezu.ernet.in
Abstract– Proper modeling of neuron plays an important role in biophysical description of action
potential of nerve fibers. Measurement in giant axon has historical importance as squid giant axon
was used extensively for voltage clamp experiments performed by Hodgkin and Huxley in 1952.
This paper presents the application of Graphical User Interface (GUI) in MATLAB in extracting
parameters for neuron modeling. The model parameters are determined based on the measurement
of action potential in earthworm giant nerve fiber with the help of PowerLab 4/25T supplied by
ADINSTRUMENTS.
Keywords–Modeling, action potential, axon, Power Lab 4/25T, GUI.
I. INTRODUCTION In early 1950, Hodgkin and Huxley carried out an elegant series of
electrophysiological experiments on a segment of squid axon. On the basis of these experiments,
they have given a quantitative description of membrane current and its application to conduction and
excitation in nerve [1]–[2]. From these experimental results, they have proposed an equivalent
circuit to account for the resistive and capacitive properties of a patch of membrane [3].

Cellular Molecules: A Compound Action Potential
A compound action potential is the sum of electrical activity produced by all the individual neurons
in a nerve that are brought to a critical membrane potential by a local stimulus. This critical
membrane potential, referred to as threshold potential, is needed to be reached during depolarization
to elicit an action potential. Two sub–threshold potentials occurring in quick succession can
summate and cause an action potential to occur even though each individual potential would not
trigger an action potential. This is referred to as temporal summation. After the depolarization phase
of the membrane, the membrane becomes completely unresponsive to stimulation, known as an
absolute refractory period. The speed at which an action potentials are

Neuropeptides
Neuropeptides are synthesized in the soma, the cell body of the neuron. These neuropeptides are
along with specific enzymes packed into vesicles in the Golgi apparatus. In these vesicles the
neuropeptides are transported along microtubules in the axon towards the nerve terminal. During the
course of this transportation the neuropeptides, who at this stage is only precursors of the actual
neuropeptides, are modified by the enzymes into their actual neuropeptide form. The vesicles in
which the neuropeptides are stored in once they arrive to the nerve terminal are called large dense–
core vesicles.
These vesicles will release the neuropeptides as a response to large stimuli, meaning stimuli which
give rise to many action potentials. The site of release is closer to the axon than the synapse and the
neuropeptides then have to diffuse toward the synaptic cleft and the ... Show more content on
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The classical transmitters are instead synthesized in the axon terminal while it is only the enzymes
necessary for their synthesis that are produced in the soma and transported along the axon. These
enzymes then act on precursor peptides, which are recycled versions of the neurotransmitter, to
produce the neurotransmitter. The neurotransmitter is then packed and stored in small clear–core
vesicles. Upon release the classical neurotransmitter bind to both GPCRs and ligand–dependent ion
channels. Therefore only the classical transmitters, and not the neuropeptides, can give rise to
excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP). As the
neurotransmitter is already in the nerve terminal and is later released directly into the synaptic cleft,
the signalling is faster than that of the neuropeptides. Classical neurotransmitters can also be
released as a response to smaller stimuli, with only a few action potentials, while neuropeptides
require stronger stimuli for

Compound Muscle Action Potential
Introduction. Compound Muscle Action Potential (CMAP) scan is a noninvasive promissory
technique for neurodegenerative pathologies diagnosis. It allows a quick analysis of the muscle
action potentials in response to motor nerve stimulation, by electrical stimulation applied on the
surface of the motor nerve and response evaluation by surface Electromyography (sEMG) at muscle
level. Each motor unit (MU) of muscles has a different stimulus intensity (SI) at which it is
activated, meaning that MUs have different thresholds. Varying the intensity of the stimuli applied,
gradually increasing from subthreshold to supramaximalvalues, will sequentially activate all MUs in
the muscle. This way, it is possible to obtain a graphical representation of the evoked action
potentials amplitude in the muscle versus the stimulation intensity. ... Show more content on
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To be used as clinical tool, stimulation parameters must be standardized and quantified in order to
enable uniform collection and comparison of data. Several studies have been made recently to verify
the potentiality of this technique, investigating the influence of different parameters in the quality of
the CMAP scan. In this work new CMAP scan protocols were implemented to study influence of
electrical pulse waveform on peripheral nerve excitability. Methods. A total of 13 healthy subjects
were tested. Stimulation was performed with an increasing intensities range from 4 to 30

A Biphasic Compound Action Potential
DISCUSSION
Biphasic CAP. For the recording of a biphasic compound action potential, both the positive and
negative recording electrodes were used, with the negative recording electrode at position 'D' and
the positive recording electrode at position 'E' (refer to Figure 1). The extracellular bipolar recording
takes the difference between what the negative electrode picked up and what the positive electrode
picked up. The first, positive deflection of the CAP was caused by the extracellular negative charge
of the action potential recorded by the negative electrode subtracted from the positive resting charge
at the positive electrode–a positive value minus a negative value yields a positive value, hence the
positive, upward deflection of the ... Show more content on Helpwriting.net ...
The compound action potential adds up all the action potentials that each individual neuron
experiences in the sciatic nerve. Different stimulus amplitudes cause different neurons to fire an
action potential; this is due to the fact that each neuron has a different threshold potential, or the
minimum voltage the neuron needs to fire an action potential. The individual neuron action potential
is an 'all–or–nothing' event, but the CAP, as a summation of different individual neurons, is not. The
CAP amplitude will increase with larger stimulus potentials because more neurons with higher
individual thresholds will be recruited. For this frog sciatic nerve, there are three fiber types, A, B,
and C. A fibers are further divided, in the order of decreasing diameter, into α, β, γ, and δ fibers.
There is an inverse relationship between the diameter of the nerve fiber and the threshold potential:
the larger the diameter, the lower the threshold. Thus, as the largest fibers, the Aα neurons will be
the first to be stimulated at a low stimulus potential, and the Aδ neuron fibers will be the last to be
recruited. Because the sciatic nerve is mostly composed of A fibers, the recruitment of A–subtype
nerve fibers are more readily distinguishable from the data. The minimum potential required to
stimulate the Aα fibers was between 75 mV and 80 mV. Once the stimulus potential reached 90 mV,
Aβ neurons were recruited and contributed to the increase in amplitude of the CAP. At a stimulus

Case Study: Amyotrophic Lateral Sclerosis
Integrating Problems
Mrs. A was recently diagnosed with Motor Neuron Disease (Amyotrophic Lateral Sclerosis). ALS is
a progressive spinal disorder that causes the myelin sheath of the neurons to disintegrate and harden
(sclerosis) which in turn inhibits the synapses of nerve impulses across the body. Mrs. A initially
started having difficulties grasping objects and performing simple tasks such as buttoning her shirts.
She then decided to visit her physician.
The Biological aspects:
The main functions of the myelin sheaths are to insulate the axon as well as increase the speed at
which action potentials are propagated between successive nodes of Ranvier, of the axon. The
Nodes of Ranvier contain voltage–gated channels that assist in boosting ... Show more content on
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The myelinated neuron is electrically modeled by Figure 2 and clearly shows the increase resistance.
This prevents the loss of current and when the signal reached the node of Ranvier the signal is
strong enough to trigger a regeneration of the impulse by the influx of Na+ ions through the voltage
gates. When the neuron goes through demyelination the resistance around the axon decreases and
electrical current is lost to the conducting extracellular fluid. This causes the membrane voltage to
decrease because voltage and current are directly proportional according to Ohms Law (V= I/R).
The electrical model of an unmeylinated axon is shown in Figure 3 and as the current travels along
the axon the current decreases due to leakage which, in turn, decreases the membrane voltage. This
results in the signal becoming weaker and weaker until it is too weak to carry the impulse to the
effector. A graphical comparison of the conduction (for one internode) found in both the myelinated
and unmyelinated neurons is shown is Figure 4 where we can see how signal strength is lost in the
unmyelinated neuron.
As we can see the integration of these three subjects greatly increases our understanding the ALS

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