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Questions tagged [peripheral-nervous-system]

The peripheral nervous system (PNS) is the part of the nervous system consisting of the nerves and ganglia outside of the brain and spinal cord.

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Chains of ganglia on each side of the nerve cord belongs to the spinal cord

One of my textbook says this: "A double chain of ganglia on each side of the nerve cord belongs to the spinal cord." But the diagrams I saw on internet depict only one dorsal root ganglion. ...
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1 answer
41 views

Can cells straddle different anatomical systems in the body?

I'm reading Periphery by Moses V. Chao, and the author explains that the peripheral nervous system consists of the portion of the nervous system outside the brain and spinal cord. But, if I understand ...
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Why electrical synapses are more common in invertebrates?

I suppose it's because they live in an environment where there's a constant vulnerability to predators and they need to respond quickly. But it's not really the case for many invertebrates and besides ...
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Could a geomagnetic storm disrupt the functioning of nerves?

It is known that geomagnetic storms can cause power grid outages. Can they also disrupt the functioning of nerves/the nervous system?
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Do nerves grow out from within or in from the skin?

The Question: Do nerves grow out from within or in from the skin? Thoughts: My guess is outwards. However, I have a vague memory of a study involving frogs that I read about in a pop science book - ...
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Confusion regarding the location of myelinated and unmyelinated nerve fibres

So, what I understand by neural system terms is Central nervous system [CNS]- consist of brain and spinal cord Peripheral nervous system [PNS] - consist of cranial and spinal nerves (all the nerves ...
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39 views

Optic Nerve: neurons/area and bit rate?

Does anyone know the number of neurons adjoining a cross sectional area of the optic nerve and the theoretical bit rate of the nerve? I read that the ON cross sectional radius is 3-5 mm and the ...
2 votes
1 answer
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What are these two nerves running parallel to the spine called?

I was looking for a human body nervous system, and often times i found a picture like the one below, where there are two nerves running parallel to the spinal column. I searched for it, but nothing ...
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Illustrating Action Potential Conduction and Ion-Gated Channels

I can separately illustrate action potential and ion-gated channels along an axon. However, I am not sure if I did the right thing on the picture below. What I'm trying to show are the simultaneous ...
10 votes
1 answer
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Does every person have unique nervous system?

If we had the technology to directly interface electronic devices with the nervous system and we wanted to connect a robotic arm to a person that lost his/her real arm, would we be able to find the ...
7 votes
2 answers
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Is the bipolar neuron of the retina considered a sensory neuron?

Any neuron that participates in sending impulses from receptors to the CNS are referred as sensory neurons. But I often see bipolar neurons of the eye (which according to the above definition should ...
2 votes
1 answer
50 views

How do humans detect temperature differentials on the skin?

I just read this question on Physics SE about how the body detects cold or warm surfaces. As someone who already understands how heat flux devices like thin film gauges and thermocouples work (by ...
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1 answer
701 views

What is the difference between a myofibril and a myoblast? (In skeletal muscle)

I read that a muscle fibre (myofiber) is formed when myoblasts fuse. https://teaching.ncl.ac.uk/bms/wiki/index.php/Skeletal_muscle#:~:text=The%20multinucleate%20feature%20is%20established%20in%...
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1 answer
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What is the difference between a dermatome and a sensory neurone?

I read that a dermatome is an area of skin supplied by a single spinal nerve but that this is sensory information? Why do spinal nerves supply the skin? I thought it was the other way round- sensory ...
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239 views

Parasympathetic effects on digestive tract - motility versus absorption

The parasympathetic nervous system's purpose is often referred to as "rest and digest." As part of this purpose, parasympathetic innervation increases motility in the digestive tract to move ...
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Is it possible to make synthetic olfactory receptors?

Are there any electronic engineering technologies that allow people to make synthetic olfactory receptor that generate electrical impulses when exposed to certain proteins or molecules? If not, what ...
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1 answer
139 views

What does it mean to say that the sympathetic nervous system is organized for diffuse activity?

"Sympathetic activities generally serve to mobilize the energy stores of the body, to increase the blood flow through certain regions (e.g., the heart) at the expense of other areas (e.g., the ...
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Why do muscle spindles send impulses at a constant rate when the muscle is at rest?

According to my book, the sensory neuron around the muscle spindle is sending impulses at a constant rate, while the entire muscle itself is relaxated (at rest). So when the muscle stretches the ...
6 votes
2 answers
6k views

How many sensory neurons are in the human body?

While I understand that there is a wide disparity of precision when it comes to specifying what constitutes "sensory neurons/receptors", I'm trying to find an authoritative source to provide ...
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683 views

Are spinal nerves myelinated and unmyelinated at the same time?

I was trying to answer this question when I remembered that the somatic axon is myelinated, while both sympathetic and parasympathetic preganglionic axons are also myelinated. Are they only myelinated ...
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Can we taste electrons?

Why does licking a 9-Volt battery elicits a taste sensation? Can taste be stimulated by electrical stimulation?
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Do large animals experience a meaningful delay when moving their most distant appendages?

According to the Physics Factbook, nerve impulses travel at speeds anywhere from 1 meter per second up to around 100 meters per second. Blue whales reach up to around 30 meters long. For a full-size ...
1 vote
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559 views

Why are spinal nerves considered a part of PNS while the spinal cord is a part of CNS?

So from my common understanding, CNS consists of brain and spinal cord, and PNS consists of everything else. But the spinal nerves - the nerves connected to the spinal cord - why are those considered ...
4 votes
1 answer
575 views

What exactly does Curare do to the peripheral nervous system?

so, I was told: If you give them the right dosage it'll wear off within an hour or two. It was used for veterinary stuff until they tried it on a human and realized it only paralyzed you and didn'...
2 votes
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Why does botulinum toxin cause only NMJ symptoms?

Botulinum toxin acts by preventing release of ACh by cleaving SNARE proteins. But if it is acting on snare proteins shouldn't all vesicle releases be effected? Why is it limited only to the ...
3 votes
1 answer
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Do hermaphrodites have more nerve fibers in their puendal nerve?

Recently I have been thinking, both the glans penis and the clitoris are the most sensitive parts of the body. They contain a lot of nerve endings. Do hermaphrodites share the nerve fibres between the ...
5 votes
2 answers
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Why do nerve gas victims have chronic neurological issues?

The article on Wikipedia says the following: The effects of nerve agents are long lasting and increase with continued exposure. Survivors of nerve agent poisoning almost invariably suffer chronic ...
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Why are some neurones unmyelinated?

As far as I am aware, most of the central nervous system consists of myelinated axons and most of the peripheral consists of unmyelinated. What is the reason for this? Would it not be more ...
5 votes
2 answers
129 views

Neurons during Numb feeling

We become numb when there is short supply of blood to some parts, as mentioned here. If that is the reason, why don't neurons and other cells die at that part if they don't receive oxygen and other ...
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If motor neurons are part of the CNS, what is the PNS made of? [closed]

It is my understanding that motor neurons transmit messages to the myocytes of skeletal muscles all over the body. This should make them part of the peripheral nervous system that transmits both the ...
1 vote
1 answer
106 views

Electric Shock To Human Body [closed]

What happens in our body when we get an electric shock?
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1 answer
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Can the dendrites of sensory neurons be a meter long?

The typical textbook structure of neurons is a cell with a short dendritic tree and a long axon. The dendrites receive information and send it to the axon via the cell body (soma). The axon is a long ...
1 vote
1 answer
216 views

How do nerve impulses travel so quickly?

Nerve impulses must travel incredibly fast to achieve the functions they do. However, I have been taught that sodium ions move down the axons by diffusion (thus causing depolarisation of the next part ...
4 votes
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Why are "itch signals" transmitted so slowly from the skin to the human brain?

In the second half of the BBC radio (and podcast) program Cats and Itch; Discovery, The Curious Cases of Rutherford and Fry Episode 2 of 5 the phenomenon and origin of the "itch" and related ...
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Nervous stimuli and neurotransmitters and impacts

As far my knowledge, in body parts generally **acetacholine ** is the neurotransmitter. Which is responsible for most nervous impulses. Consider a body part, say, foot. Only one nerve reaches here. ...
2 votes
2 answers
959 views

Does every nerve ending send information to the brain separately?

Does every nerve ending send information to the brain separately? Is there a nerve path (I don't know their scientific name) from every nerve ending to the brain; or are they sent to brain from the ...
4 votes
2 answers
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How does the mechanism which controls blood pressure in the brain work?

I know that pressure is sensed in the skin by mechanoreception mediated by skin receptors. Static pressure stimuli are mainly sensed by slow-adapting fibers connected to receptors like the Merkel ...
64 votes
4 answers
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Are there organisms with fewer than 1000 neurons?

I'm developing neural networks comprised of just 3 to 10 layers of virtual neurons and I'm curious to know if there are any insect brains out there with fewer than a thousand neurons? Are there any ...
2 votes
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Dorsal root fibres

How can dorsal root fibres be unmylinated though are responsible for conduction of pain and temperature? How is their conduction so fast without even being myelinated? Is presence of only one axon( ...
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2 answers
440 views

Do Schwann cells have Na+/K+ ATPase pump? [closed]

I was studying "Action Potential" and this question crossed my mind. Another question is that, "Why does the action potential not occur in Schwann cells, or if it does, how does it occur?" I know that ...
2 votes
1 answer
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How does motor nerve innervation determine type of muscle fibre?

Muscle fibres are of two types - type I and type II. They differ from each other in various properties. Even the underlying biochemical processes are different to suit their function (slow vs fast) ...
3 votes
1 answer
750 views

Why is Capsaicin injection not used instead of nerve surgeries for pain?

High concentration capsaicin kills c & a-delta nerve fibers permanently or at least long term. This has been known for 30 years. But capsaicin is only used in creams and patches, and not for ...
3 votes
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How does gold chloride stain neuromuscular junctions?

Gold chloride is used in muscle biopsies to stain the NMJ. What is the substrate that it binds to?
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What would happen if nerves didn't have refractory period? [closed]

What would happen if nerves didn't have refractory period? And, what part of his nervous system or neurons are not needed?
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Is it possible to feel pain in some part of a body, but the pain "feeling" is introduced somewhere else?

Is it possible to feel pain in some part of a body, but that the cause of the pain is situated elsewhere in the body? For example, somebody feels pain in his toe, but it turns out that this pain is ...
3 votes
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How is recruitment of multiunit smooth muscle cells fine tuned if they are innervated by varicosities?

In my physiology textbook (Silverthorn) and on wikipedia it says that: Multiunit smooth muscle tissues innervate individual cells; as such, they allow for fine control and gradual responses, much ...
2 votes
1 answer
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Anatomy of nervous system's sensory pathways

When I touch my hand on a hot stove, I feel pain. I'm interested in knowing all the main "endpoints" (components/parts of the body) that are involved in relaying this pain signal. As I understand it ...
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1 answer
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Relationship between nerves and axons

I just wanted to get a realistic viewpoint of our nervous system. I understand arteries and veins, but I wanted to know how similar our nervous system is to that? I understand we have neurons (...
2 votes
2 answers
11k views

Why we shiver/tremble/shake while performing some work which requires high accuracy?

Shivering when nervous or anxious is a common thing. But, shivering or trembling sometimes also occurs when we are performing a work which requires high accuracy. In such case, our whole body doesn't ...
4 votes
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Why sympathetic and parasympathetic nerves originate in different parts of CNS?

Curious if there is a reason for having: parasympathetic nerves originating from brain stem and pelvic part of spinal cord sympathetic nerves originating from thoracic and lumbar parts It looks well-...