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82 votes

Are there organisms with fewer than 1000 neurons?

Short answer As far as I know, a complete neural map (a connectome) is only available for the roundworm C. elegens, a nematode with only 302 neurons (fig. 1). Fig. 1. C. elegans (left, size: ~1 mm) ...
AliceD's user avatar
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62 votes

Do large animals experience a meaningful delay when moving their most distant appendages?

Yes, larger animals do experience larger delays in movement. There have been studies of size difference vs sensorimotor delays in terrestrial mammals, https://www.ncbi.nlm.nih.gov/pubmed/30158304 ...
bandybabboon's user avatar
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25 votes

Are there organisms with fewer than 1000 neurons?

The organism you are looking for is the nematode C. elegans, which always has the same number of neurons, 302, and has been fully mapped, see WormWeb or you can chase original publications from there. ...
Jack Aidley's user avatar
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24 votes

Does every person have unique nervous system?

Probably the best way to answer this question is with a counterexample to humans: the nematode worm C. elegans has 302 neurons. Every individual has exactly that number, and each is found in the same ...
Bryan Krause's user avatar
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16 votes
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Is it possible to feel pain in some part of a body, but the pain "feeling" is introduced somewhere else?

Yes, this is pretty common. Examples include sciatica, pain felt down the back of a leg to the foot, from irritation to components of the sciatic nerve but commonly at the level of the sciatic ...
Graham Chiu's user avatar
16 votes

Are there organisms with fewer than 1000 neurons?

I believe there are types of water snail with 8 distinct neurons in a ganglia, there's a bit of information here: molluscs.at. The cell bodies of the neurons are massive, visible under a standard ...
Oliver Houston's user avatar
8 votes

Are there organisms with fewer than 1000 neurons?

Re: insect brain size Following article has a good summary — in short insects' nervous systems range from 7400 to 850000 neurons: http://blogs.discovermagazine.com/notrocketscience/2011/11/30/how-...
Dima Tisnek's user avatar
7 votes
Accepted

Do hermaphrodites have more nerve fibers in their puendal nerve?

Short answer The genitals of true intersex individuals are not duplicated. Instead, their external genital features are hybrid structures. In turn, it's not a matter of duplicated neural innervations. ...
AliceD's user avatar
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6 votes

Is it possible to feel pain in some part of a body, but the pain "feeling" is introduced somewhere else?

An example of pain evoked by distant sites in the body is referred pain. It's defined as pain perceived at a location other than the site of the painful stimulus. An example is the case of angina ...
AliceD's user avatar
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5 votes
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Are spinal nerves myelinated and unmyelinated at the same time?

Spinal nerves are mixed nerves containing afferent and efferent neurons of various types. Anatomically, they protrude from the spinal column bilaterally at each vertebral level. They contain both ...
De Novo's user avatar
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5 votes
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What exactly does Curare do to the peripheral nervous system?

Curare is a plant alkaloid originally used as a poison on darts and arrows used in hunting. It is a competitive antagonist for the nicotinic acetylcholine receptor, which is found in the neuromuscular ...
De Novo's user avatar
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5 votes
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Is the bipolar neuron of the retina considered a sensory neuron?

In short, yes. Any neuron that is involved in conveying sensory information from the periphery to the CNS is a sensory neuron. So I would consider all of those neurons in the retina sensory. Arguably ...
Oliver Houston's user avatar
5 votes

Is it possible to feel pain in some part of a body, but the pain "feeling" is introduced somewhere else?

Another common medical condition that causes pain elsewhere is the spinal disc herniation. The disc pushes against the nerves in the spinal and causes pain, usually in the leg, foot or arm. https://en....
RHA's user avatar
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4 votes

How many sensory neurons are in the human body?

This is a really interesting question. However, I'm going to try to address the context and update sections of your post rather then attempt to quantify all afferent signals in the nervous system. ...
Marina McPeak's user avatar
4 votes
Accepted

What are these two nerves running parallel to the spine called?

From this closeup image, you can see there is more than one nerve on each side that is parallel to the spine. Source: imgur.com First, they are the right and left sympathetic trunk that run from the ...
Jan's user avatar
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3 votes
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What is the difference between a dermatome and a sensory neurone?

This is just a confusion of English. "Supplied" is a bit of a weird term to use, I agree, due to the direction of information flow, but feel free to substitute in just "connected to&...
Bryan Krause's user avatar
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3 votes

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

There is a simple answer to your question: it might cause a massive inflammation-like response and it might also hurt really, really badly. Capsaicin activates heat receptors which are not only ...
AlexDeLarge's user avatar
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3 votes
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Do Schwann cells have Na+/K+ ATPase pump?

Yes. Although utilizing the action potential is not in their function, Schwann cells do have Na/K ATPases. In fact all animal cells do. It contributes to the resting membrane potential in neural ...
Liu Tianyi's user avatar
2 votes

Is the bipolar neuron of the retina considered a sensory neuron?

Short answer According to definitions, I can say 'yes' to all your statements. Background So what are sensory neurons? Are [] retinal neurons sensory? Yes they are considered sensory neurons, ...
AliceD's user avatar
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2 votes

Does every nerve ending send information to the brain separately?

As commented, a nerve ending is really the ending of a neuron, some sensory neurons travel directly to the brain, some form synapses in the spinal cord (most touch and pain neurons from the body), ...
Oliver Houston's user avatar
2 votes
Accepted

Does every nerve ending send information to the brain separately?

There are two main structures in the human nervous system: The central nervous system, which includes the brain and spinal cord The peripheral nervous system, which is all of the nerves in the rest ...
Dart Feld's user avatar
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2 votes
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How does motor nerve innervation determine type of muscle fibre?

'Slow' and 'fast' motor neurons differ in their firing patterns. This differentially affects intracellular calcium concentrations and energy usage of the innervated muscle fibers over time, and ...
pbond's user avatar
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2 votes

Is it possible to feel pain in some part of a body, but the pain "feeling" is introduced somewhere else?

Just as an FYI, the answer is emphatically yes. I have two separate areas of my body which exhibit those symptoms. But my answer does not "track" those of others here. They talk about (I would ...
Cbohica's user avatar
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2 votes
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Why do nerve gas victims have chronic neurological issues?

I would like to add a bit to Chris' answer. While it is true that the underlying mechanism of the long lasting effects of nerve gas has not been established, several hypotheses exist (reworded from ...
Thawn's user avatar
  • 1,239
2 votes

Why do nerve gas victims have chronic neurological issues?

Most of the nerve agents (and quite a number of commercially used pesticides) fall into the class of organophosphates (OP). Their mechanism of action is the inhibition of the acetylcholin esterase ...
Chris's user avatar
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2 votes
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How do humans detect temperature differentials on the skin?

Sensory neurons in the skin express TRP channels such as TRPV1 channels, TRPM8, and others (see Voets et al 2004 for more information on how these channels work). Different sensory neurons express ...
Bryan Krause's user avatar
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1 vote

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

Myoblasts are the embryonic precursors of myocytes (also called muscle cells). Myoblasts differentiate into muscle cells through a process called myogenesis. A myofibril (also known as a muscle fibril)...
Noob's user avatar
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1 vote
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What does it mean to say that the sympathetic nervous system is organized for diffuse activity?

"Mobilize" in this context means to: to release (something stored in the organism) for bodily use Merriam-Webster "Diffuse" means "spread out": it doesn't say anything about whether the effect is ...
Bryan Krause's user avatar
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1 vote

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

CNS consists of brain and spinal cord, and PNS consists of everything else That's really it. The distinction is slightly arbitrary, I'd think of them as the central (nervous system) and the ...
Bryan Krause's user avatar
  • 45.9k
1 vote

If motor neurons are part of the CNS, what is the PNS made of?

The peripheral nervous system refers to parts of the nervous system outside the brain and spinal cord. It includes the cranial nerves, spinal nerves and their roots and branches, peripheral nerves, ...
Graham Chiu's user avatar

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