How many neurons are needed to send a signal from the tip of the finger to the spinal cord to withdraw hand when we touch a hot object one neuron?five neuron? millions of neurons? or thousands of neurons? Do we understand what is there in the textbook? is it logical?
Can a similar connection that is seen in the Reflex action? do we understand the differences between the nerve and the neurons? What is ganglion what is the brain made up of? what is a spinal cord made up of? is there any difference between ganglia and brain?
"A typical secondary school textbook depicts a diagram of just a single neuron.
Are we relying on that?
What will be the difference if a single neuron is passing the signal or thousands of neurons are passing the signal?
And
How long will it take for the signal to convey in all of the above four cases?"
–quoting @drishtantmkawale
“In today’s ChatShaala, we discussed a bunch of possibilities of a signal being transmitted from a human fingertip to the spinal cord.
Four separate propositions were made to answer the question: how many neurons are needed to send a signal from a fingertip to the spinal cord?.
i) Only a signal neuron.
ii) 5 neurons are needed
iii) Thousands of neuron form a connection to pass the signal.
iv) As many as a million connections are needed.”
–quoting @drishtantmkawale
If we go logically and understand by taking a single neuron for passing the signal from the fingertip to the spinal cord, the dendrites(extensions from the cell body/soma) can be thought to be residing in the fingertips of all the five fingers. The cell body can reside in our palm and the axon can extend through the length of our hand till the spinal cord where the axonal terminals are ready to pass the signal.
The signal is an alternating signal from an electrical signal to a chemical signal.
All of this by a single neuron!
This may not/may be true but this seems logical.
Multiple neuronal connections to the spinal cord can increase the time taken by the reflex to generate action (not trying to humanise).
Quoting @drishtantmkawale
Withdrawal of our hand involves the role of sensory and motor neurons as well as inter neurons which co ordinate our movement1) across the spinal cord, 2) across the two types of muscles of the arm, one will contract and the other extend for movement to occur3) the other hand will also move simultaneously hence inter neurons will need to connect the other arm too.
Hence more than two(sensory and motor) neurons will be involved in the withdrawal action.
Agreed.
Withdrawal of our hand does involve the role of sensory, motor and interneurons.
The objective behind the earlier proposition of involving just a single neuron was to pass the signal from the fingertip to the spinal cord and not the withdrawal of our hand. @magpie
What were the issues with your current design for preparing colored Moina?
How do you think this can be prevented through Collaboration? @drishtantmkawale hat were the issues with your current design for preparing colored Moina?
How do you think this can be prevented through Collaboration? @drishtantmkawale
Are you sure? Why not state this as a testable Hypothesis and make a design to test this Hypothesis of yours @drishtantmkawale
Otherwise it will remain another guess work!
Looking forward to developing better understanding about the Moina culture system… @drishtantmkawale
Wow! Just a text book diagram ‘covers up’ a lot…prompting students to do nothing other than to ’ mug up…’!
Why teachers don’t address these huge gaps & misconceptions!!! “…and leave the kids alone…?!!”
Eric Kandel’s research question or his objective was to study learning and memory behaviour.
These behaviours can be studied by observing the neurons…
Human body has about billions of neurons. It would be easier for Eric Kandel to observe a body having less neurons as compared to human body. Observing and studying billions of neurons is not easy.
This could be the reason that Eric Kandel selected sea slugs which has just 20,000 neurons (less as compared to human body)
“Learning about the human brain from sea slugs”
Kandel and his team soon identified a simple defensive reflex in the slug similar to the human reflex to quickly pull one’s hand away from a hot object. Scientists once thought that only higher order animals could learn, but Kandel soon showed that slugs could be taught to modify this reflex. “It was, for me, very exciting, because I had never done these behavioral experiments before,” recalls Kandel.
Quoting @Lydia
‘One neuronal cell body in the palm of our hand’…! How large the cell body of that neuron be? @drishtantmkawale Saida 5-6 cm? @drishtantmkawale
quoting @Arunan
it can be around 4 to 100 micrometre in diameter
Withdrawal of our hand involves the role of sensory and motor neurons as well as inter neurons which co ordinate our movement1) across the spinal cord, 2) across the two types of muscles of the arm, one will contract and the other extend for movement to occur3) the other hand will also move simultaneously hence inter neurons will need to connect the other arm too.
Hence more than two(sensory and motor) neurons will be involved in the withdrawal action.
Great chance to find out connection between Human Nervous system and Snail Nervous system, and as Eric Kandel also preferred sea slugs to study Nervous system(simple) and connect it to Human Nervous system (which is very complex).
Can we find some relavent reference for this?..
[12:24 PM, 10/20/2020] Kiran CUBE HBCSE: Great!!! How many cells/Neurons are involved from tip of our finger to the spinal cord???. Or how many cells/Neurons are involved to send signal from spinal cord to biceps (muscle or arm)??..Or relay this signal to neuron which will give this signal to Brain…?.or actually Brain is not involved in this process of withdrawing hand after getting stimulus from hot plate???.
Can we say that Neuron is the largest cell of the Human body??.
Ohhh do you think to perform this quick action Brain is involved in both Human and snail??..
quoting @KiranyadavR
As it is a quick response to the stimulus, brain will not be involved in the withdrawal of the tentacle as well as the hand.
Yes.
Withdrawal of our hand does involve the role of sensory, motor and inter neurons.
The earlier proposition of involving just a single neuron was to pass the signal from the fingertip to the spinal cord and not the withdrawal of our hand.
[12:43 PM, 10/20/2020] Drishtant FY: What is the role of interneurons here?
Which two parts are getting connected here?
Is it that interneurons are connecting motor neurons and the spinal cord?
+91 98423 80616 joined via an invite link
[12:55 PM, 10/20/2020] Drishtant FY: No, the cell body cannot be as large as 5 to 6cms but 4 to 100 micrometres.
“the soma of a neuron can vary from 4 to 100 micrometers in diameter.”
We can actually visualise 100micrometres!!
If we take a 15cm scale, there would be markings of 1cm and further there would be smaller markings/divisions that would be of 1mm.
1000micrometres=1millimetre
100micrometres=0.1mm
A full stop (.) would be of that size!
It would not be right to say that neurons are the largest cells in the human body.
We can say that neurons are the longest and at the same time, the smallest cells in human body.
So, the soma or head of neuron with dendrites will be at fingure tip n long axon or cylindrical body will be extended upto the motor if its single long cell to carry impulse or signal. Or a number of neurons will be arranged following each in ‘head of later neuron near tail of prior neuron’ n carry signals?
N also we have a number of different neurons… like one taking signal from the body to spinal cord, next ones sending signal from spinal cord to body. Both assigned for the respective function… Right?
Yesterday while discussing about this great scenario of Neuron signal passing in context to when we either touch a hot object with our hand and what we observe is that we remove our hand in a fraction of seconds. (hot object) + (hand touched) - (hand removed immediately)
What is happening that causes this quick removal or retraction of our hand in terms of signals between neurons ?
Yesterday everyone tried to give own logical explanation to the scenario of hand withdrawn upon touching a hot object.
We discussed that there are neurons that are present near palm that recieve signal with the receptor on the dendrites.
Case 1
If there was just one neuron that will carry signal
@Saida and others argued that it will take less time to pass the signal from the neuron at hand till the spinal cord…
Case 2
If there are 5 neurons that carry signal of hot object from our hand to spinal cord, it will take comparatively more Time to pass signal from our hand to spinal cord.
Why does it take more time for 5 neurons to pass the signal till the spinal cord as compared to just one neuron?
Because in between two neurons there is a gap known as the synapse
And signal from one neuron end to the next neuron therefore takes more time
Below can be referred to as a single neuron -
‘’
And now 5 neurons from our hand till the spinal cord with the gaps in between…
But is this really true? @Arunima@Arunan Sir @Kiran CUBE HBCSE @Lydia Mathew @Drishtant FY @Saida@Lakshmi and others.
[2:22 PM, 10/20/2020] Yash Hbcse: I think gill-withdrawal response is similar to what @Anjani Kumar et al are looking at in the Giant African snail Tentacle withdrawal response…
When anjani touched left tentacle of the giant African snail, it “withdrew” Both its tentacle…
Is it? @Anjani Kumar FY @Saida
The Aplysia gill and siphon withdrawal reflex (GSWR) is an involuntary, defensive reflex of the sea hare Aplysia californica, a large shell-less sea snail or sea slug. This reflex causes the sea hare’s delicate siphon and gill to be retracted when the animal is disturbed.
So @batul maam that is the role of the spinal cord?
To connect the two parts of our body, the left and the right, in this case our hands and
also connect the response of withdrawal of both hands?
from sea slugs”
(hot object) + 
(hand touched) - 
(hand removed immediately)
’
maam that is the role of the spinal cord?