Resting Membrane Potential Lab Report

Resting Membrane Potential Lab Report
Resting Membrane Potential The first part of the lab we did fours exercises having to do with resting
membrane potential. The purpose of part one of the MetaNueron experiment is to observe resting
membrane potential. Membrane potential is defined as the difference in electrical potential between
the interior and exterior of a cell. Resting membrane potential refers to such that the cell is at rest
and is not receiving or sending any signals. It still has a potential difference across its membrane
such that the inside of the cell is negatively charged relative the outside. We used the MetaNueron
program to do our experiments. There were four different colored lines on the computer screen. The
baseline at 0mV which was red, the Na+ potential which was blue, the K+ potentials which was
green, and the membrane potential which was yellow. The baseline is the starting point used for
comparisons of all the graphs and figures. The Na+ and K+ potentials are the membrane ... Show
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ENa was +58mV and Ek was –85.6mV. We then changed the Na+ gradient by manipulating the Na+
concentration outside from 20 mM to 120 mM. As we increased the Na concentration outside the
ENa became more positive while EK remained the same. The resting membrane potential became
more negative. ENa is 0mV when the Na+ concentration inside and out are both equivalent. The
Nernst equation allowed us to calculate the reversal potentials: Vm=58log C_1/C_2 . This equation
only accounts for the concentration gradient of a single permeable ion. The Goldman equation
allowed us to calculate the overall resting potential, which takes into account multiple ions and the
relative permeability of each: Vm=–58log (P_K 〖[K]〗_i+P_Na 〖[Na]〗_i)/(P_K 〖[K]〗
_o+P_Na 〖[Na]〗_o ). This graph can be seen below in Figure
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Cell Signaling Essay
Cell signaling in the central nervous system refers to the communication that occurs in cells to
coordinate* cell actions, as the cells receive and respond to other cells to help with many functions
in the body, from immunity to development to growth.
Cell signaling begins at the axon of the cell, which is the long fiber part of a nerve cell where
electrical impulses are conducted and sent from the cell body through the axon to other cells. At the
axon the action potential (define short–term change in the electrical potential on the surface of a cell
(e.g. a nerve cell or muscle cell) in response to stimulation, and then leads to the transmission of an
electrical impulse (nerve impulse) that travels across the cell membrane.) is conducted. ... Show
The voltage dependent sodium and potassium channels are closed. A stimulus would then cause the
voltage dependent sodium channels in the neuron's membrane to open, causing the Na+ ions that
were outside the membrane to rush into the cell. This would cause the cell to become more positive.
If the signal is strong enough to cause the voltage to reach a threshold, in which the positive charge
reaches somewhere between –40 and –55 mV, it causes a depolairsation as the cell's charge is a
reverse due to it being more positively charged while the outside of the cell, lacking in Na+,
becomes negatively charged.
The depolarization triggers the sodium channels to close, and the voltage dependent potassium
channels to open, causing K+ to move out of the cell to reduce the concentration gradient**. This is
the repolarisation stage, as the inside of the cell becomes more negative as the K+ ions leave the
cell.
The neuron is then hyperpolarised when there are more K+ on the outside than Na+ in the inside of
the cell, meaning the cell has a more negative charge than the outside of the cell. This causes the
cell's potential to be slightly lower than its' initial resting potential. This is the last stage of an action
potential, after which there is a refractory (resting) period until which the cell returns to its' resting

Neurone Function Essay
Membrane proteins are found in all cell membranes and it is these that determine the majority of the
membranes functions. There are often two types of membrane protein and these can be classified as
integral proteins and peripheral proteins. Integral proteins are situated in the hydrophobic interior
part of the phospholipid bilayer and can have hydrophilic channels that allow the passage of
hydrophilic substances across the membrane. Where as, peripheral proteins are not embedded in the
bilayer at all and are instead loosely bound to the surface of the membrane. Neurons are the basic
units of the nervous system and are involved in the transmission of impulses to all different parts of
the body. Membrane proteins are of great importance when it comes to considering the function of
neurones within the body, as many of the processes that occur would not be possible without the
action of proteins.
One of the key ways that membrane proteins are involved in neurone function is through the
formation of the resting potential. The resting potential is the charge difference across a cell
membrane when a neurone is at rest and not sending a signal, typically between –60 and –80
millivolts. Potassium and Sodium ions play a fundamental role in the formation of the resting
potential (Professor Sandidge/Moyle, 2012) and these ions each have a concentration gradient
across the membrane of a neuron. In the majority of neurones, the concentration of potassium is
greater inside the cell,

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

How Are Neurons Specialized For Communication? How Do Not...
Answer each of the following questions and the separate parts of each question as completely and
directly as possible. Do not go off–track or give "fluff" answers, as that could count against you.
1. (6pts) Diagram a neuron and label its components. In what ways are neurons specialized for
communication? How do these specializations distinguish neurons from other types of cells?
The structure of a neuron consist of four main components dendrites, cell body also known as soma,
synapse and axon. Dendrites collect signals coming in from other cells. The soma is responsible for
assimilating signals coming in from the dendrites in order to create a signal traveling unidirectional
through the axon. The axon stems from the soma, which ... Show more content on Helpwriting.net
...
In the organization of the Human Nervous System it is divided into sections such as the sensory
system, which gathers and process information from the surrounding environment: motor systems
which responds from environment by sending signals and information to facilitate movement
behavioral responses and the associational system which is a meditator from most multifaceted and
least problematic brain functions. Within these different functions of the nervous system it is divided
into two components where these functions can happen the central nervous system that comprises of
brain and spinal cord and peripheral nervous system that embodies nerves and ganglia.
Using Functional MRI helps to visualize the brain functionality through local metabolism. In this
technology it allows the researcher to measure and track the brain functions by discovering the
correlated changes in blood flow. From this functional Mri when a brain function is acted out the
flow of oxygenated rich blood is detected and highlighted on the specific location where the
functionality came from on the brain.
In study of neuropsychology we are able to learn about the brain structure and function. Then from
that we are able to study the nervous system and the brain through neurobiology. In the study of
neuropsychology we are now able to know that

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

Project Classroom Makeover Analysis
In "Project Classroom Makeover", Cathy Davidson demonstrates the potential benefits that can
come from the implementation of technology in the current educational paradigm. Furthermore, in
Sherry Turkle's "selections from Alone Together", Turkle discusses the unique relationship between
a child and his or her artificially intelligent toys, some of which included Tamagotchis and Furbies.
Interestingly, children give these toys special treatment relative to other toys. If the special treatment
encourages positive behavior, then these toys could be potentially implemented into the current
educational paradigm as a new form of technology. Therefore, the real question is are there benefits
of allowing children to play with these toys, or will there ... Show more content on Helpwriting.net
...
As discussed before, as long as these toys do not shut down in response to pain and do not overly
express their pain by crying, these toys should be safe in a school environment. Also, if these toys
respond to behavior like the Tamagotchis and Furbies, then it will be beneficial to allow children to
play with these toys during school time. This is due to the ability of "computers...[that can] turn
children into philosophers" (Turkle, 463). For the Duke university students, computers enabled them
to create new applications for the iPod. Therefore, the computers helped turn them into a type of
philosopher, one that thinks innovatively. The iPod experiment is a perfect example of benefits of
applying technology to the education system because it did in fact turn young adults into a type of
philosophers. For children, computers turned them into a type of philosophers by transforming them
"into caretakers" (Turkle, 464). Philosophers of this type thinks emotionally and understands that all
life, even "digital life, can be emotionally roiling" (Turkle, 464). When children play with their
Tamagotchis and Furbies, they can experiment their actions with toys and not with people. This
allows for them to understand the consequences of mistreating

Structure Of The Key Components And Overall Reaction...
Chart 1 describes the structure of the key components and overall reaction pathways of the present
photocatalytic CO2 reduction based on a TiO2 hybrid system with an antenna and Re–based
molecular catalyst; : the antenna, is (E)–2–cyano–3–(5′–(5″–(p–(diphenylamino)phenyl)thiophen–
2″–yl)thiophen–2′–yl)–acrylic acid (Dye);, molecular catalyst (ReP), is fac–[Re(4,4'–
bis(diethoxyphosphorylmethyl)–2,2′–bipyridine)(CO)3Cl];, and the electron donor (ED), is 1,3–
dimethyl–2–phenyl–1,3–dihydrobenzimidazole. These compounds were prepared according to the
literature methods.33,36––38 The hybrid catalyst was prepared by sequentially anchoring the Dye
dye and ReP on TiO2 semiconductor (Hombikat) sequentially. Successful anchoring of the
components was confirmed by the absorbance comparison before and after each adsorption step of
catalyst (Figures S2 and S3). In each adsorption step, the solution layer separated by centrifugation
of the treated suspension was nearly transparent. The hybrid particles were dispersed in N,N–
dimethylformamide (DMF) containing ED (0.1 M) in the absence or presence of H2O (3 vol%, 10
vol%, and 20 vol%), saturated with CO2 and then irradiated at >400 nm using an LED lamp (60 W,
Cree Inc.). Chart 1 Schematic representation of heterogeneous ternary photocatalytic system for CO
production: electron donor (ED), sensitizer (Dye), and reduction catalyst (ReP). 3.2. External
factors: energy level control of TiO2 semiconductor by hydration and additives –

Resting Potential Research Paper
The resting potential of a membrane is when it is negatively charged due to the movement of the
positive ions out of the cell. More of the potassium ions diffuse out of specialized gated channels of
the nerve cell than the number of sodium ions that diffuse into it. In addition to this movement of
ions, active transport of ions occurs due to the Na+/K+ pump which moves or pumps out the
respective Na+ and K+ ions at a ratio of 3:2. Because the axon loses a greater number of positive
ions than it gains, the inside of its membrane is negative in relation to the outside. The unequal
concentration of positive ions across the nerve cell membrane gives rise to the negative resting
potential. Polarization is the charge of the resting membrane which is polarized due to the
concentration gradient created by the higher number of potassium ions inside than the sodium ions
outside. At rest, the potential ... Show more content on Helpwriting.net ...
When an axon becomes stimulated a rapid change occurs in the electrical potential difference across
the nerve cell membrane, and registers at +40mV. The cell membrane becomes more permeable to
sodium than potassium. The gates of the sodium channel open and the gates of the potassium
channel close. Sodium ions rush into the nerve cell because of the electrochemical gradient. The
rapid influx of sodium ions causes a charge reversal known as depolarization. Once the inside
becomes positive the sodium influx is stopped and its gates close. As soon as the inside of the cell
becomes positive, the sodium–potassium pump in the cell membrane starts up again to pull
potassium in and push sodium out. The process of restoring the original polarity of the nerve
membrane is called repolarization. Nerves can't be activated again until the repolarization process is
complete and usually lasts 1 to 10 ms, this timeframe is called the refractory

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

A Report On The Energy Project Programme
Assignment A
During the summer of 2014 I took part in the Energy Project programme, I was paired with a small
heating–engineering company, Global Celsius solutions. The company had recently developed a
cheap, rugged and reliable water boiling system, the "Jompy" boiler. The system itself took
advantage of compact heat exchanger design principles incorporating a high surface area,
minimising the footprint of the system without sacrificing overall performance, the boiler was
capable of producing water in excess of 70oC within a matter of 5–7 seconds(from my own
experience with the boiler). The overall aims of the project included:
1. Researching possible rental markets, with an emphasis on sustainable development.
2. Effects of transport ... Show more content on Helpwriting.net ...
The purpose of the hiring of the local partners is to take advantage of their knowledge of the local
populace, for example if a potential customer has a reputation of looking after their belongings and
being good on their word concerning their repayments, then a set minimum deposit would be
implemented, and vice versa for a person notorious for abuse of equipment and poor money
management. The key would be to ensure that the monthly repayments would remain consistent.
After approximately 8 months the "Jompy" is paid off, instead of increasing profitability of the
scheme after this benchmark all excess repayments are invested back into local development and
infrastructure (schools, education fees, stationary etc). My task was to investigate potential problems
faced by the model and if any companies had successfully implemented like–minded schemes. To
accomplish this, the potential problems of the model had to be identified in this case one of the main
problems involved initiating an honest and mutually beneficial relationship with these Sub–Saharan
local communities. This came in the form of formulating potential marketing strategies and
suggesting forms of engagement towards those who would benefit most from the product. Another
of the main goals

Potassium ( K + ) Channels
Potassium (K+) channels are ubiquitous throughout biological systems as they are found in many
different cell types including prokaryotes, eukaryotes and archaea. (However, for the scope of this
exam, the examples will be limited to K+ channels found in neurons.) They are tetrameric integral
membrane proteins that assemble to form transmembrane aqueous pores. Their basic function is to
allow the passive flow of potassium ions down an electrochemical gradient rapidly and with high
specificity. The high specificity of these channels is crucial in excitable cells such as neurons as they
are able to exclude sodium ions (Na+) despite the sub–angstrom difference between ionic radii,
which allows for the establishment of ion gradients as well as a delayed flow between sodium and
potassium ions to shape action potentials. This specificity also allows the channels to establish and
maintain the resting potential in many cells.
All potassium channels have a distinctive, universal feature of two transmembrane (TM) helices and
a short loop ("P loop") between them that lines the top of the pore and is responsible for potassium
selectivity. This canonical feature is referred to as 2TM/P. In terms of membrane topology, there are
two broad classes of K+ channels: 1) the two–transmembrane–helix (2TM/P) subunit, typical of the
inward rectifying (KIR) channels and, 2) the 6–transmembrane–helix (6TM/P) subunit, typical of
voltage–gated (KV ) subtypes. It must be noted that the 6TM/P

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

Neuron Lab Report
Neurons or nerve cells come in all shapes and sizes however, they all do one thing. They transmit
information the way electrical wires or optic cables carry information. Neurons form the necessary
connection that makes the body "go". Neurons consist primarily of two processes. One process is
the dendrites, they receive information from other neurons. The other process is the axon and they
send information or impulses out to other neurons, muscles or glands of the body. An unstimulated
cell is called the resting membrane potential. Each cell has positively charged ions outside of the cell
and negatively charged ions inside during this state. An action potential is a series of sudden changes
in the voltage, or equivalently the electrical potential, ... Show more content on Helpwriting.net ...
In Activity 1 we set our hypothesis to find out the potential voltage difference across a cell that's at
rest. We used a computer to simulate explaining how the membrane is permeable more to potassium
than sodium due to potassium has more leak channels than sodium does. The cell maintains a stable
resting membrane thus the membrane is polarized. In Activity 2, our hypothesis is to find out how
stimulus modalities induce amplitude receptor potential. We used three sensory neurons. Pacinian
corpuscle had a resting potential of –70mv except a receptor potential of the biggest amplitude to
pressure. Olfactory receptor had an increase with chemical modality only. Heat, light and pressure
this receptor stayed in the resting membrane potential. The free nerve ending stayed in the resting
membrane potential except to heat. In Activity 3 our hypothesis was to find out how much stimulus
voltage would it take to cause an action potential? With our computer simulation, we started at 10
mv with no action potential results. We increased to 20 mv and we had an action potential. Action
potentials are all or none. You could keep increasing voltage from this point on and continue to
achieve action potentials. In Activity 7 we are using a computer simulation. We have three fibers, all
with different myelination and

Resting Membrane Potential Research Paper
Hanan Yusuf
BIO 350–002
In order to understand electrical signaling in biological membranes, we must know the basic
properties of the resting membrane potential. Electrical signaling of biological membranes is
required for effective cell–to–cell communication in our bodies (Watson et al. 2015). In order for the
conduction of electrical signals along membranes to occur, cells must be excited. Before excitation
occurs, the cell membrane is at rest; this state is known as resting membrane potential. The resting
membrane potential results from a separation of charges across the membrane. Additionally, at this
state there is no massive ion movement across the membrane.
Initially, the potassium concentration is larger inside of the cell than outside whereas the sodium
concentration is larger outside of the cell than inside. As a result, the aforementioned ions will travel
down their concentration gradient; potassium ... Show more content on Helpwriting.net ...
As a result, the K+/Na+ ATPase pump actively transports potassium into the cell and sodium out of
the cell in order to maintain the membrane potential of the cell. This process requires energy
because the pump goes against the concentration gradient of the ions. As a result, the potassium
concentration is higher inside of the cell than outside and the sodium concentration is higher outside
of the cell than inside. This causes a large net diffusion of potassium out of cell and only a small net
diffusion of sodium into the cell in order to establish equilibrium potential (Sherwood et al. 2013).
More potassium diffuses via the membrane than sodium because the membrane is 25X more
permeable to potassium than to sodium (Purves et al. 2001). The resting membrane potential value
for a typical cell is –70 millivolts, which is closer to the equilibrium potential of potassium due to its
high

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

Membrane Potential Lab Report
Membrane potential, Transmembranes potential & its measurement by microelectrodes 1.
Introduction Background 2. Physiology of Membrane Potential 2.1 Understanding Membrane
Potential 2.2 How to Calculate Membrane Potential 3. Transmembrane Potential 3.1 Measurement
of Transmembrane Potential by Microelectrodes Summary In all cell types, there is an electrical
potential difference exits between the inside and outside of the cell resulting from the differential
concentrations of sodium and potassium on either side of the membrane. This is termed the
membrane potential of the cell. While this phenomenon is present in all cells, it is especially
important in muscles and nerve cells, because changes in their membrane potentials are used to code
and transmit information or signals. More specifically, the action potentials are electrical signals;
these signals carry efferent messages to the central nervous system for processing and afferent
messages away from the brain to elicit a specific ... Show more content on Helpwriting.net ...
Na+/K+ ATPase pump continuously three sodium ions to the outside for each two potassium ions
pumped to the inside of the membrane. The fact that more sodium ions are being pumped to the
outside than potassium to the inside causes continual loss of positive charges from inside the
membrane; this creates an additional degree of negativity on the inside beyond that which can be
accounted for by diffusion alone. Therefore, the net membrane potential with all these factors
operating at the same time is about −90 millivolts. In summary, the diffusion potentials alone caused
by potassium and sodium diffusion would give a membrane potential of about −86 millivolts, almost
all of this being determined by potassium diffusion. Then, an additional −4 millivolts contribute to
the membrane potential by the continuously acting electrogenic Na + /K + ATPase, giving a net
membrane potential of −90

Physioex 3 Essay
ACTIVITY 1: THE RESTING MEMBRANE POTENTIAL
1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out the neuron through
the K+ leak channels?
When the diffusion is greater on one side, the other side will slow down.
2. Explain why increasing extracellular K+ causes the membrane potential to change to a less
negative value. How well did the results compare with your predictions?
There are two potassium's for every sodium so the increase of potassium will make it more negative.
Prediction was correct.
3. Explain why a change in extracellular Na+ did not alter the membrane potential in the resting
neuron?
The sodium channels are mostly closed during the resting state.
4. Discuss the relative ... Show more content on Helpwriting.net ...
Does the Pacinian corpuscle likely have this isoamyl acetate receptor protein? Does the free nerve
ending likely have this isoamylacetate receptor protein?
No
6. What type of sensory neuron would likely respond to the green light?
Physical sensory.
ACTIVITY 3: THE ACTION POTENTIAL: THRESHOLD
1. Define the term threshold as it applies to an action potential.
It is the transmembrane potential at which an action potential begins.
2. What change in membrane potential (depolarization or hyperpolarization) triggers an action
potential?
Depolarization
3. How did the action potential at R1 (or R2) change as you increased the stimulus voltage above the
threshold voltage? How well did the results compare with your prediction?
It did not change. Prediction incorrect.
4. An action potential is an "all–or–nothing" event. Explain what is meant by this phrase.
All stimuli that bring the membrane to threshold generate identical action potentials. The properties
of the action potential are independent of the relative strength of depolarizing stimuli.

5. What part of a neuron was investigated in this activity?
The Axon.
ACTIVITY 4: THE ACTION POTENTIAL: IMPORTANCE OF VOLTAGE–GATED NA+
CHANNELS
1. What does TTX do to voltage–gated Na+ channels?
It irreversibly blocks voltage gated sodium channel in the

Physioex 9.0 Laboratory Review 03-09 Essay
Exercise 3: Neurophysiology of Nerve Impulses: Activity 9: The Action Potential: Putting It All
Together Lab Report Pre–lab Quiz
Results You scored 100% by answering 4 out of 4 questions correctly.
1. Sensory neurons respond to an appropriate sensory stimulus with a change in membrane potential
that is You correctly answered: b. graded with the stimulus intensity.
2. If the depolarization that reaches the axon is large and suprathreshold, the result in the axon is
You correctly answered: c. action potentials at higher frequency.
3. At the axon terminal, each action potential causes the release of neurotransmitter. This
neurotransmitter diffuses to the receiving end of an interneuron, where it binds to receptors and
causes ... Show more content on Helpwriting.net ...
Why is there a larger, depolarizing response at R1 when you apply a moderate intensity stimulus?
You correctly answered: c. The stimulus induces a graded receptor potential at R1.
Experiment Data: Stimulus Sensory Neuron Membrane Potential (mV) Receptor –70 –60 –40 –25
Sensory Neuron AP Frequency (Hz) in Axon 0 16.6 33.3 Sensory Neuron Vesicles Released from
Axon Terminal 0 4 6 Interneuron Membrane Potential (mV) Receiving End –70 –70 –50 –40
Interneuron AP Frequency (Hz) in Axon 0 5 10
None Weak Moderate Strong
Post–lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly.
1. What determines the amplitude of the depolarization at the sensory receptor (R1)? You correctly
answered: a. The strength of the stimulus applied to the sensory receptor.
2. What determines the frequency of action potentials in the axon of the sensory neuron (R2)? You
correctly answered: a. The amplitude of the depolarization at the sensory receptor (R1).
3. Which of the following directly determines the amount of neurotransmitter released at the axon
terminal of the sensory neuron? You correctly answered: c. The amount of calcium that enters the
sensory receptor.

4. Which of the following directly or indirectly determines the amount of neurotransmitter released
at the axon terminal of the sensory neuron? You correctly answered: d. All of the above play a role
in determining the amount of

Mild Traumatic Brain Injury Essay
The brain is vulnerable, and is susceptible to mild traumatic brain injuries (mTBIs). A person's head
jerks forward and back; this rapid change in acceleration causes a concussion because of impact.
Examples of impact injuries that frequently occur in athletics are collisions, falls, and bumps to the
head. Regardless of how a person sustains a concussion, her brain collides with ridges in her skull.
Although the purpose of a skull is to protect the brain; the fusion of bones in a person's skull creates
ridges, and these ridges damage the brain upon impact. When a person's brain is shaken up, the
sharp ridges damage the prefrontal cortex and temporal lobes (Hirsch & Kaufman, 1975).
The Centers for Disease Control and Prevention (CDC) suggest that 17 percent of reported
concussions are caused by sports–related accidents (CDC, 2014). Concussions affect approximately
1.7 million Americans every year, and this equates to about 300,000 reported ... Show more content
on Helpwriting.net ...
Increased intracellular calcium triggers the activation of calpain. Calpain, a calcium dependent
proteolytic enzyme begins apoptosis (Momeni, 2011). Apoptosis occurs because calpain degrades
the membrane, cytoskeleton, and the cell's DNA. Calpain, in the presence of calpastatin, an
endogenous inhibitor protein, unregulates calpain activation (Momeni, 2011). Calpain consists of a
two catalytic subunits; within the 80kD subunit there are four domains, domains I through IV.
Domains for calcium binding are found in first four EF–hands; the fifth EF–hand goes around the
subunits thus creates a heterodimer interface (Todd, Moore, Deivanayagam, Lin, Chattopadhyay,
Maki, Wang, & Narayana, 2003). During activation, domain I hydrolyses other proteins and these
proteins go from the 80kD subunit to 30kD subunit (Suzuki, Hata, Kawbata, & Sorimachi 2004).
After that, the active site cleft is rearranged because two calcium atoms bind (Suzuki, Hata,
Kawbata, & Sorimachi

Essay BIOS252 Week 3 PowerPhys4 Lab Report 2
LABORATORY REPORT
Activity 4: Generation of Action Potentials
Name:
Instructor:
Date:
PREDICTIONS
1. Exceeding the threshold depolarization at the trigger zone DECREASES the likelihood of
generation of action potential.
2. Action potential amplitude: DOES NOT CHANGE with distance
3. Increasing frequency of stimulation to the trigger zone: DOES NOT increase the production of
action potentials.
MATERIALS AND METHODS
Experiment 1: Effect of Stimulus Strength on Action Potential Generation
1. Dependent Variable Membrane potential
2. Independent Variable
Stimulus strength (voltage)
3. Controlled Variables
Frequency of stimulation
Type of neuron
Experiment 2: Effect of Frequency of Stimulation on Action Potential ... Show more content on
Helpwriting.net ...
Action potentials can occur more frequently as long there is a continued source of stimulation, as
long as the relative refractory period has been reached, which in experiment 2 the refractory period
was complete.

5. Restate your predictions that were correct and give the data from your experiment that supports
them. Restate your predictions that were not correct and correct them, giving the data from your
experiment that supports the correction.
1) Exceeding threshold depolarization does not change the likelihood of an action potential being
produced, Due to the need for a refractory period this is (all or nothing) In the experiment from 6V–
8V in the axon hillock the difference in amplitude went from 30.2 to 30.9 (not a remarkable
increase)
2) Amplitude does not change with distance. . From the experiment, the action potential amplitude
does NOT change as it propagates down the axon. (The change was small at 0.4, 0.2) 3) Increasing
frequency of stimulation of the trigger zone does not increases the production of the action
potentials. This goes back to the threshold All or nothing theory.
APPLICATION
1. ECF potassium levels affect resting membrane potential. Hyperkalemia (excessive levels of
potassium in the blood) and hypokalemia (abnormally low blood potassium levels) both affect the
function of nerves and muscles.
Explain how hyperkalemia will

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
Helpwriting.net ...
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

The Mechanisms Of Neural Communication
Discuss the mechanisms of neural communication and explain the impact that different drugs can
have on this communication.
Neural Communication
Everything we do is a product of neural communication, whether that be reacting to senses or
feeling emotions, it is all due to us having neural communication through millions of neurons
passing small electrical signals throughout the body through such pathways as the central nervous
system and the peripheral nervous system and passing information to and from the brain. These
''neurons'' are made up of Dendrites which are connected to a cell body, or also known as the soma,
these are tree–like feathery filament ''message receivers'' that collect these messages from other
neurons it is connected to, neurons are connected through a dendrite to axon terminal connections
and pass these ''messages'' through the body as action potentials.
As well as these there are also the axon of the cell which is covered in myelin sheaths which carried
information away from the cell body and hands the action potentials, these are small short bursts of
change in the electrical charge of the axon membrane through openings of ion channels, off to the
following neurons dendrites through terminal buttons at the end of the axons. Whenever an action
potential is passed through these terminal buttons it releases a chemicals that pass on the action
potential on to the next neuron through the terminal button and dendrite connection. The chemicals
that are

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

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

Cardiac Conduction
Cardiac Conduction
To complete this worksheet, select:
Module: Distribution Activity: Animations Title: Cardiac Conduction
1. What is the function of the Conduction System? All cells must contract in a specific sequence.
This sequence is determined by the pathway known as the conduction system.
2. Cardiac cells are connective and autorhythmic. What does this mean? Connective cells, action
potentials, (excitatory signals) can propagate from one cell to another via gap junctions.
Autorhythmic cells can excite themselves spontaneously without stimulation of the nervous system
and contract at a regular rhythm.
3. Cells from different parts of the heart's ... Show more content on Helpwriting.net ...
The signal moves quickly from the SA node through the atria where it experiences a slight delay
when it reaches the AV node and it must pass into fibers with smaller diameters. The signal then
quickly resumes along its path through the AV bundle branches apex and base of the ventricles
contraction begins.
7. What happens at each of the following points of a normal ECG?
P – Atrial excitation (atrial depolarization).
QRS – Ventricular excitation (ventricular depolarization).
T – End of ventricular excitation (ventricular repolarization).
8. Contrast a healthy heart ECG with an abnormal one in which ventricular excitation is independent
of atrial excitation (P waves). The sequence of depolarization and repolarization can be seen in a
normal electrocardiogram usually called the ECG. The electrocardiogram can also show problems
with the conduction system. Look at this trace showing complete heart block by comparing the QRS
waves to the P waves. You can see that ventricular excitation is independent of atrial excitation. The
pace of ventricular excitation is being sent by the ventricles slower natural rhythm not by stipulation
from the SA node atria.

9. Contrast the resting potential of typical myocardial cells with that of SA nodaL cells. A typical
contractile cell in the

Crayfish Resting Membrane Potential Essay
The purpose of this experiment was to test the hypothesis that the crayfish resting membrane
potential is primarily dependent on the potassium ion concentration gradient. Our approach to
testing this hypothesis involves taking intracellular recordings using an IWX/214 interface, iWorx
and LabScribe software, and a Model 3100 electrometer complete with a head stage, ground
electrode, glass microelectrodes, and micromanipulator. The study organism used for this
experiment involved the abdominal extensor muscles of adult Orconectes rusticus. One–sample t–
tests were conducted on the resulting membrane potentials and their corresponding predicted values,
taken from the Nernst Equation. The results of the statistical analysis rejected the null hypothesis
only for some potassium gradient concentrations, and while there might be enough evidence to
suggest that there is a relationship between the potassium gradient concentration and crayfish resting
membrane potential, we cannot conclude from this experiment a primarily dependent relationship.
Introduction ... Show more content on Helpwriting.net ...
While both models in question agree that there is a relationship between the potassium concentration
gradient and resting membrane potential, we are not addressing other permeable ions that might also
have an influence. While this particular topic is still under debate, Tomasz Sokalski et. al. suggested
in their study, "Numerical Solution of the Coupled Nernst–Planck and Poisson Equations for Liquid
Junction and Ion Selective Membrane Potentials", that while the Nernst–Planck model is proposed
to be a more appropriate platform for dealing with the theory of ion selective membrane electrodes
for analytical applications, it can be shown that interpreting the electrical potential of plasma
membranes exclusively in terms of boundary potential at steady state is incorrect (Sokalski et. al.

Neuron Function
When a neuron is not sending a signal, it is at rest. When a neuron is at rest, the inside of the neuron
is negative relative to the outside. At rest, potassium ions are at higher concentration inside the
neuron. While there's a higher concentration of chloride ions and sodium ions outside of the neuron.
There's also negatively charged protein molecules inside the neuron, which cannot cross the
membrane. When the neuron is at rest, it has a resting membrane potential, voltage between the two
layers, is –70mV. When the dendrite of the neuron receives a stimulus, and when the stimulus
depolarizes the cell to its action potential threshold of –55mV an action potential will occur. If the
neuron does not reach this threshold level, then no action

Neural Tissue
Chapter 12: Neural Tissue – An Introduction to the Nervous System
Learning Outcomes
12–1 Describe the anatomical and functional divisions of the nervous system.
12–2 Sketch and label the structure of a typical neuron, describe the functions of each component,
and classify neurons on the basis of their structure and function.
12–3 Describe the locations and functions of the various types of neuroglia.
12–4 Explain how the resting potential is created and maintained.
12–5 Describe the events involved in the generation and propagation of an action potential.
12–6 Discuss the factors that affect the speed with which action potentials are propagated.
12–7 Describe the structure of a synapse, and explain the mechanism involved in ... Show more
content on Helpwriting.net ...
rent neurons of PNS
Interneurons – association neurons
Functions of Sensory Neurons
Monitor internal environment (visceral sensory neurons)
Monitor effects of external environment (somatic sensory neurons)
Structures of Sensory Neurons
Unipolar
Cell bodies grouped in sensory ganglia
Processes (afferent fibers) extend from sensory receptors to CNS
Three Types of Sensory Receptors
Interoceptors
Monitor internal systems (digestive, respiratory, cardiovascular, urinary, reproductive)
Internal senses (taste, deep pressure, pain)
Exteroceptors
External senses (touch, temperature, pressure)
Distance senses (sight, smell, hearing)
Proprioceptors
Monitor position and movement (skeletal muscles and joints)
Motor Neurons
Carry instructions from CNS to peripheral effectors
Via efferent fibers (axons)

Two major efferent systems
Somatic nervous system (SNS)
Includes all somatic motor neurons that innervate skeletal muscles
Autonomic (visceral) nervous system (ANS)
Visceral motor neurons innervate all other peripheral effectors
Smooth muscle, cardiac muscle, glands, adipose tissue
Preganglionic fibers
Postganglionic fibers
Interneurons
Most are located in brain, spinal cord, and autonomic ganglia
Between sensory and motor neurons
Are responsible for:
Distribution of sensory information
Coordination of motor activity
Are involved in higher functions
Memory, planning, learning
12–3 Neuroglia
Neuroglia
Half the volume of the nervous

Ice Observation
The witness has been the manager at the Ice Rinks for the last 4 years. He reviews ice contracts and
is only involved with the interior portion. He reports to Gart Snow who is the general manager of
the New York Islanders and employees. Other employees who make up the team and shoveled the
snow are Scott Berge, Joseph Fin, Richard Glass and Jimmy Carumma. The work was directed by
the witness. The assistant manager is Christina Mott. There are approximately 40 cars in the parking
lot, in front of the building and about 10 cars in back of the building. Landscaping in front of the
building is closest to the sidewalk and it has front and back entrances. The front entrance is for the
general public and the back is for employees. There is one entrance/exit at the front. In January and
February he would inspect the area daily if it was snowing. The witness would inspect the parking
lot with his men. He would look for snow and ice by walking through the whole lot. His inspection
of the parking lot included an inspection of the sidewalk. ... Show more content on Helpwriting.net
...
He used a bucket of salt provided to him by Preferred Landscape. The bucket was about 1' high. He
used no sand. The bucket would be replenished whenever the witness called John to replenish it.
John signed a proposal, not an agreement for snow removal. The witness saw the bobcat used by
Preferred to remove snow from the parking lot as well as from the sidewalk. It would be pushed
forward to let cars park. According to the proposal, John was to respond 24x7x365, meaning at all
times but the witness recalls having to call him for his lack of presence. The witness saw Preferred
throw sand on the parking lot and sidewalk. The sand was on a truck and was removed by a
machine. The trucks were also moving and spreading over 10

Bloodstream Discrimination: A Case Study
"Baxter initiated a voluntary nationwide recall of one lot of IV solution due to the potential for
leaking containers, particulate matter and missing port protectors". This recall was issued on July
17, 2015. Leaking containers, particulate matter and missing port protectors could result in
contamination of the solution. If not detected, this could lead to a bloodstream infection or other
serious adverse health consequences. Injecting a product containing particulate matter, in the
absence of in–line filtration, may result in blockage of blood vessels, which can result in stroke,
heart attack or damage to other organs such as the kidney or liver (U.S. Food and Drug
Administration, 2015).
Baxter 0.9% Sodium Chloride injection USP is intended

The Nervous And Endocrine Systems
Introduction The nervous and endocrine systems both function to maintain the stability of the
internal environment. While both systems may work together as a single Neuroendocrine system,
the systems may also work alone performing communications, integration and control within the
body. (Patton and Thibodeau, 2010) The endocrine system consists of eight major glands; the
hypothalamus, pituitary, thyroid, adrenals, pineal body, reproductive organs and the pancreas. These
glands are widely separated from each other with no physical connections. Endocrine glands are
groups of secretory cells surrounded by an extensive network of capillaries that facilitate diffusion
of hormones from the secretory cells into the bloodstream. Hormones are then carried in the
bloodstream too target tissues and organs that may be quite distant, where they influence cellular
growth and metabolism. (Waugh, Grant and Ross, 2010) Hormones Hormones are important when
gradual changes in the body are needed, such as; puberty and growth hormones that are used during
this process. They are gradual because the messages are sent through the blood system. Hormones
are controlled by glands, they decide how much, if any, are secreted. Some key examples of
hormones in the body are as follows... Hormone Secreted from Function Adrenalin Adrenal medulla
Affects muscle and liver cells, adrenalin increases heart and metabolism rates. Released to prepare
the body for 'fight or flight' response. Insulin Beta cells

Biological Pathways And Signaling Within The Brain
One field of study in the realm of biology that still leaves much to be discovered is neuroscience,
more specifically, the neurological pathways and signaling within the brain. While there have been
many developments and breakthroughs in identifying areas of activity and neural pathways, there
are still many obstacles to overcome and discoveries to be made. The authors of the journal High–
fidelity optical reporting of neuronal electrical activity with an ultrafast fluorescent voltage sensor
sought to overcome one such obstacle. They understood the potential for fluorescent proteins to be
used for visualizing the firing of action potentials throughout neuronal pathways of the brain, but
realized that such proteins were unable to accurately record higher frequency signaling across
synapses where there was frequent action potential activity. Within this journal, they describe the
methods used to produce a new fluorescent protein, accelerated sensor of action potential
1(ASAP1), and the benefits that it can provide to the field of visualizing the activity of action
potentials as they propagate through synapses in the brain. They hypothesized that ASAP1 should be
able to give definitive fluorescent readings for the activity of action potentials propagating through
the brain, even in areas with high frequency activity that have not been measurable before. In order
to create this revolutionary new fluorescent visualization protein, the researchers had to test it in
many

Resting Membrane Potential Essay
The first step of four is called the resting membrane potential, the resting membrane potential is also
known as polarized. At this stage no ions move through the voltage–gated channels, both sodium
and potassium gates are shut. A neuron (which is a specialized cell transmitting nerve impulses) is
resting. At resting state, the membrane potential of a neuron is roughly –70mV (millivolts), so the
cytoplasmic side (which is the inside) is negatively charged parallel to the outside. All gated Na+
and K+ channels are closed at this stage. A Na+ channel each has two gates, 1 being an activation
gate which is closed at rest but swings open when depolarization occurs, the second being and
inactivation gate that ceases the channel once swung open. Although for Na+ to enter both gates ...
Show more content on Helpwriting.net ...
This is where the Na+ channels are inactivating, this allows the K+ gates to swing open. Due to their
being a lot more Na+ ions on the outside and the inside the sodium dashes into the neuron first,
sodium is a positive charge, so during depolarization the neurons become a lot more positive. As
time passes the Na+ channels inactivates allowing the K+ channels to swing open the K+ channels
take more time to open, but once they fully have unfortunately, the internal negativity resting
membrane is restored to –70mV (Marieb ; Hoehn;, 2010).
The fourth and final step is called Hyperpolarization. This is a dramatic change in the cells
membrane potential which makes it more negative than the resting membrane potential. It is the
complete opposite of depolarization. Hyperpolarization is also considered as a undershoot, due to it
dropping below step 1 (resting membrane potential) during the hyperpolarization stage a small
amount of K+ channels remain open while the Na+ channels reset, the Na+ channels reset to their
original position by changing their shape to further reopen their inactivation gates by closing the
activation gates (Marieb ; Hoehn;,

Resting Potential: An Electrical Difference Across Cell...
To create a voltage across the cell membrane there must be Resting Potential: an electrical
difference across the membrane of a nerve cell during an inactive period. This electrical difference
generates a voltage that must be maintained to create a "ready state" that allows the cell to fire or
create action potential across the axon. Without Resting Potential, there is no driving force for the
main ions inside and outside of the cell. Neurons' intracellular fluid tends to be more negatively
charged while their extracellular fluid tends to be more positively charged. Specifically, a neuron at
rest exhibits a characteristic resting potential of about –50 to –80 millivolts. In order for neurons to
maintain this difference, the lipid bilayer of the membrane must be impermeable to charged ions.
Because of the charge imbalance, or electrical gradient, ions naturally want to diffuse through the
membrane; the plasma membrane must be able to prevent this. This is important when it comes to
potassium (K+) ions. There tends to be a large difference in the concentration, or chemical gradient,
of K+ between the inside and outside of the cell. Because there is a higher concentration of K+
inside the cell, the potassium wants to diffuse out of the membrane to achieve equilibrium. There is
only one–way to achieve this: ion channels. Ion channels are ... Show more content on
Helpwriting.net ...
So you are forced to open the door, and go back into the lobby, dreading that you will have to go
through security again. Potassium ions face this same ordeal. Because positive and negatives attract,
the potassium ions are sucked back through the ion channels into the cell to depolarize it (or make a
neutral charge). This whole process will happen repeatedly until the neuron concentration of ions is
restored. This force is called the electrical gradient. This creates an even charge across the
membrane, which is resting membrane

Resting Membrane Potential Of Orconectes Lab Report
This experiment seeks to analyze how the resting membrane potential of Orconectes rusticus muscle
cells changes in response to increasing [K+]o solution concentrations. By recording the intracellular
voltage of the DEM, DEL1, and DEL2 crayfish muscle cells at six concentrations of [K+]o solution,
we determined whether the observed resting membrane potentials (Vrest) were significantly
different from the predicted Nernst equilibrium potential values. We hypothesized that the Vrest of
the crayfish muscles at each concentration would not significantly differ from the Nernst potential,
which solely considers the permeability of potassium ions to the cell membrane. However, our
findings suggested differently, and results indicated that the Nernst equation did not accurately
predict the obtained values of the resting membrane potential. The differences in muscle cell Vrest
reveal instead that the membrane is differentially permeable to other ions. I. Introduction: ... Show
Both electrical and chemical forces combine to determine the resting membrane potential of the cell.
Although the resting membrane potential of most cells is normally negative, the selective
permeability of the membrane allows certain ions in and out, causing the neuronal membrane
voltage to become depolarized (more positive), or hyperpolarized (more negative). Key ions
involved in muscle membrane potential are sodium, potassium, and chloride, which move via
passive or active diffusion through ion channels and transporter pumps (Baierlein et al. 2011). The
Nernst equation predicts the membrane voltage based on the assumption that the membrane is only
permeable to one type of ion. In this investigation, we are seeking to understand the basis for how
different ions interact to produce the membrane potential of DEM, DEL1, and DEL2 crayfish
muscle

Essay on What is a Neuron?
What is a Neuron? Human brain consists of billions of cells interconnected together, with each
performing its separate functions. It consists of two explicit categories of nerves: neurons and glia
cells. Neuron is a single nerve cell in the entire nervous system; which is electrically excitable cell
that carries information after being processed via chemical or electrical signals. One of its key
characteristics is that it does not undergo cell division. In addition, it maintains a voltage gradient
for all the neurons across its membranes. Glia cells, on the other hand, its functionality is to
maintain homeostasis.
Different Components of a Neuron Neuron cell is made from numerous components: soma,
dendrites, axon, and ... Show more content on Helpwriting.net ...
Whenever the balance is altered, the process of transmitting electrical signals, which is called action
potential initiates by carrying information across a neuron's axon; which is called resting membrane
potential. This process occurs as uneven ions distribution flow across cell membrane, creating
electrical potential. As a result, the duration of active potential can be as fast as 1 ms. Similarly, the
average resting membrane is between –40 mV and –80 mV. Since the membrane from inside is more
negatively charged than the outside, it reflected on the negative average voltage readings of the
resting membrane. As soon as the electrical signal reaches the end of the axon, mechanism of
chemical alteration initiates. First, calcium ion spurt into the axon terminal, leading to the release of
neurotransmitters "molecules released neurons which carries information to the adjacent cell". Next,
inside the axon terminal, neurotransmitter molecules are stored inside a membrane sac called
vesicle. Finally, the neurotransmitter molecule is then discharged in synapse space to be delivered to
post synaptic neuron.
Chemical Transmission – Graded Potential Graded potential is one of the methods of transmission
of chemical information from one neuron to another. It occurs in specific regions in neural cell, such
as: post–synaptic plasma membrane "dendrite or soma" or regions of sensory stimuli reception.
Difference in levels of chemical concentration causes

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

Notes On Nerve Impulses
PHYSIOEX 9.0 REVIEW SHEET EXERCISE 3 Neurophysiology of Nerve Impulses NAME :
_HIMA BHARATHA ________ LAB TIME/DATE: WEDNESDAY A.M. LAB______ ACTIVITY
1 The Resting Membrane Potential 1. Explain why increasing extracellular K+ reduces the net
diffusion of K+ out of the neuron through the K+ leak channels. ___The concentration of
extracellular K+ ions would be high and this would prevent more K+ ions from diffusing out of the
cell. 2. Explain why increasing extracellular K+ causes the membrane potential to change to a less
negative value. How well did the results compare with your prediction? ___ My prediction was that
the membrane potential will not change and that was wrong because the resting membrane potential
changed from –40V to 0V. This happened because K+ diffuse out across the membrane and they
leave a net negative charge behind. ___ ___ 3. Explain why a change in extracellular Na+ did not
alter the membrane potential in the resting neuron. ___ _There are less leakage channels for Na+
compared to K+_that's why it didn't alter the membrane potential in the resting neuron._ 4. Discuss
the relative permeability of the membrane to Na+ and K+ in a resting neuron. ___ _ The resting
neuron is 4 to 5 times more permeable to K+ then to Na+ because of the leakage channels._ ___ 5.
Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential. ___
_There would be a greater change in the resting membrane potential in K+ than in Na+ because of
more K+

Resting Membrane Potential Lab Report

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