Biology Stack Exchange
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Questions tagged [neurophysiology]

The study of the physiology of the nervous system, with emphasis on transcellular communication, and cellular and molecular processes involved in neural communication.

The study of the physiology of the nervous system, with emphasis on transcellular communication, and cellular and molecular processes involved in neural communication.

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Why is it possible to calculate the equilibrium potential of an ion using the Nernst equation from empirical measurements in the cell at rest?

In trying to understand the Nernst and GHK equations, I've hit upon a snag somewhere deep in my understanding of the subject matter. Scenario 1: when calculating the membrane potential of a living cell at rest we use the Goldman equation. This…
Vladimir Gritsenko
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Behaviour of neuron when membrane potential is maintained at threshold potential or more

Via an external electrode the membrane potential of a neuron or group of neurons can be increased from resting potential of -70 mV to -50 mV or more. This will cause them to fire an action potential. What happens if the electrode maintains the…
jkl
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Are there calcium channel blocking neurotoxins?

I am learning about calcium ion channel blockers (CCBs) and am confused whether there are neurotoxins that are CCBs. If they exist, what is an example of a CCB neurotoxin? What animals use CCB neurotoxins as a weapon / defense tool?
Stan Shunpike
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Presynaptic inhibition

For presynaptic inhibition, I am aware of these: Ca²+ influx (into the presynaptic nerve terminal) is decreased. And this in turn reduces the probability of releasing synaptic vesicles from the presynaptic neuron. The influx of Ca²+ is under the…
Chemo-Mike
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What phase of Action Potential (AP) exactly defines the Relative Refractory Period?

I am posting below, word for word, two statements made on Relative Refractory period - the first from the text: Human Physiology for Medical Students by Magdi Sabry, and the second from a web page with the…
Chemo-Mike
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Is magnetic resonance microscopy appropriate for investigating ion-channel flow?

I've been looking into ways to characterize the elecrophisiology of neurons for cell signaling and I came across magnetic resonance microscopy as a tool for gaining images of neuronal activiy at a large scale. This made me question, is it possibly…
Iustinian Olaru
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Cardiac vs. skeletal muscle contraction

For the heart muscles, it is the extracellular Ca2+ that is necessary for the contraction, but for the skeletal muscles, it is intracellular Ca2+. One of my answers on a test was the following: "In cardiac muscles, an augmentation of the…
Uyen Phuong NGUYEN
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Focusing your attention on an area within your body, what effect does it make?

When I focus on tactile signals from a certain part of my body for a while (e.g. for one minute), this part of the body will usually become warmer. For example I can do that with a certain finger or with my palm, or with a certain spot on my forearm…
Roman Vinogradov
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Unmyelinated long axons in the sympathetic nervous system

I was recently looking over some textbook material (pdf) which claimed post-ganglionic fibers of the sympathetic nervous system are unmyelinated. This was surprising to me, since I had previously thought that long distance transmission of an action…
Hans
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What does Guyton mean by "the ratio must be grater than one" when it comes to the safety factor to start an action potential?

All­or­Nothing Principle. Once an action potential has been elicited at any point on the membrane of a normal fiber, the depolarization process travels over the entire membrane if conditions are right, but it does not travel at all if conditions are…
Quique
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How does the original ionic distribution restore after synaptic transmission

During synaptic transmission the calcium ions around the presynaptic membrane diffuse in due to the influx of Na+ ions and the resulting depolarization. This happens because the calcium channels are voltage regulated ones. At the same time on the…
Ubaid
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Why myelin sheat does not cover the whole axon?

Is there an optimal lenght for myelin sheats to be effective and lead potential across the nerve cell? This has always bugged me.
Liv
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What happens to the empty space ion pumps create?

Sodium-potassium pumps pump two potassium ions in and three sodium ions out. That means that it creates space for one more ion. Eventually, it's going to be filled. The concentration will be fine, as it would be 3 sodium out and 3 potassium in…
Sentient Rays
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Why isn't the resting membrane potential at equilibrium?

There has been a question asked regarding the purpose of ion pumps, and the main answer was that the resting membrane potential isn't in an equilibrium state, so the potassium keeps flowing out. Other sources claim this, too. But why is this the…
Sentient Rays
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Does positive electricity run through neurons in the exact same way as it runs through copper?

Does positive electricity moves in the exact same way as electric current moves through copper,silver and gold? From what I understand, electricity propagation in neurons is not linear as it is in a wire but rather in a cross-sectional way, moving…
Quique
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