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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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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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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 ...
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Why do Epipens not also contain a dose of Norepinephrine alongside the Epinephrine?

The purpose of Epipens, as I understand it is two-fold, reduce the swelling of the smooth muscle to prevent asphyxiation while increasing the heart rate to offset the capillary dilation. My question ...
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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 ...
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Do muscles and connective tissue have different types of pain receptors?

I assume that muscles have pain receptors ("nociceptors"?) that fire when the muscle is under excessive strain or even tears or becomes injured. I also assume that similar pain receptors exist for ...
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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'...
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What is the nueral pathway for auditory information from the retina of the eye till it reaches the occipetal lobe of the cereberal cortex?

The book I'm going on mentions that the midbrain relays auditory and visual information (to,I assume, the temporal and occipetal lobes respectively. I don't know which regions , but just that it's in ...
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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 ...
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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 ...
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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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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 ...
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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 ...
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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 ...
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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. ...
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Electric Shock To Human Body [closed]

What happens in our body when we get an electric shock?
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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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Is the bipolar neuron of the retina considered a sensory neuron?

Any neuron that participates in sending impulses from receptors to CNS are referred as sensory neurons. But I often see bipolar neurons of eye(which according to the above definition should be sensory ...
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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 ...
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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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312 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 ...
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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 ...
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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) ...
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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 ...
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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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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 at least ...
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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 ...
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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 ...
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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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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 ...
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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 ...
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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 ...
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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-...
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Any nerves/fibers in foot similar to ulnar nerve in elbow?

I just noticed that when I gently run my fingers along the top of my right foot, I get the same exact "funnybone" sensation in my toes that I get when I hit the ulnar nerve in my elbow. So I ask: are ...
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Why isn't the upper limit of pain lower in humans?

From what I understand, pain is an useful mechanism that signals us that something is not quite right with our body (in particular, we're under attack). It's good - it alert us and tells us that we ...
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132 views

Who is organizing the heartbeat and its roles in the body?

Throughout the decades we heard that the heart is the only muscle whose nervous system is not acting. So who is he responsible for organising the heartbeat and its roles?
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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 (...
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How can a brainless Cnidarian hunt and defend itself?

Cnidaria, such as jelly fish and sea anemones are radial symmetric en feature a simple body plan. One notable aspect is the lack of a brain. Hence, there is no central guiding structure, no mind or ...
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Does the nervous system have “routers”?

Does the peripheral nervous system have a system of routers that decide where a message is meant to go based on some kind of address, or does a signal from the brain follow a single, unbroken chain of ...
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314 views

Specific location where nerves converge

I'm looking for the "earliest" specific site where the 3 following nerves' sensory signals "converge": Trigeminal nerve Median nerve Superficial peroneal nerve By "earliest", I really mean the first ...
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Names of nerves in hands, shins and face

I am looking for the names of the nerves in 3 specific locations of the human body: The nerve running along the "top" (opposite side of the palm) portion of the thumb, from knuckle to fingernail (see ...
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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 ...