Really appreciate Leslie making all these videos. It helps me in my study of optometry courses and i have better understanding. It's very helpful for those student that lack of imagination. this video just help me to have a clear view and better understanding of the parts and structures
Excellent video series. Not certain why persons are being so critical, when they are clearly made to give students a general understanding. Thanks, You've helped sooo much!
Very coherent, well explained, good diagrams, very good breakdown of the processes. Only one mistake, though a major one and basic still does not take away from what a great video this is. Thanks!
@joinmebowser9000 What you see in this video is what happens in response to light. So light enters, hits the rods, and then this process (shown in the video) happens. It's very similar in the cones, but uses different pigments (not rhodopsin).
This was the one part of our unit that confused me so much (prof went through it super fast) thank you for this, it's helped me understand more. Thank you!!!!!
@joinmebowser9000 No such thing as a dumb question. Yes, we use rods to see at night, but even then - that's because light is entering our eyes. We can't see with light (even when it's relatively dark). Hope that helps answer your question.
@bizz76 I'm sorry, but Leslie won't be able to answer your question as he is busy with a lot of stuff. He'll be making more Biology videos for the site though tackling more systems and other topics, so stay tuned for more! :)
Thanks for the video, but you might want to correct your graph of membrane potential. Open cGMP-gated channels keep membrane potential relatively "depolarized" and permissive for glutamate release from terminal. Closing these channels causes an increase in membrane potential, not a decrease as drawn.
@Ckaotenkind Well, we're glad to know you've gained something from it. We hope you aced your test. Stay tuned because we have new Biology videos coming very soon :)
thanks so much for your help I bet this is a very good explanation but I am so confused maybe I need to watch video more than once. Thanks again for your hard work and interest in educating the world :)
I don't think it will complicate things, just chemically speaking there is a big difference and writing the wrong one down in an exam is not the best. If you just kept it as retinal throughout the video, then i would consider it a general introduction and wouldnt criticise. in all fairness, its great that things like this are available on youtube and that people take the time to upload them. i would keep it as retinal for simplicity and only mention the retinol etc in a more in depth video.
Appreciate your video! Nonetheless I wanted to inform you that what you said in minute 0:47 isn't quite correct from what I know. The foeva does not contain both cones and rods. The foeva only contains cones; thats why visual acuity is best there. Have an amazing day :).
At about 9:50 you mentioned a "depolarization" from cGMP gated-ion channels. but you also said that Na+ ions were leaving the cell, wouldn't this cause a hyperpolarization?
Yes it will cause Hyperpolarization, but the moment it happens, this polarization of membrane will release neurotransmitter into the synapse of the rods membrane and the bipolar neuron, thus impulse is generated to the occipital region for vision processing.
I always thought that the rods and cones' resting state was a depolarized membrane potential, and they are constantly releasing NT onto the bipolar cells. Once visual transduction processes have been performed that constant stream of NT is shut off creating a change in membrane potential of the bipolar which can code for ON or OFF. (NT = neurotransmitter)
Madjack Your last comment is correct. Some Na+ ions are always leaving the cell, whether it's light or dark, due to the ongoing activity of the Na+/K+-ATPase, which pumps Na+ out and K+ in. On its own, this would cause the membrane potential to be set at approximately -70mV (which is the case for many neurons). However, in photoreceptor cells, the cGMP-gated Na+ channels allow Na+ ions to diffuse into the cell faster than they are being pumped out by the sodium-potassium pump, causing the cell to be depolarised in the absence of light.
I just got a little question. Aren't rods them we see with in the night? Then why does the procces begin when the light comes in, and not when it stops? And sorry for my dumb question, but I just came to see about rods and cones, and I haven't seen any of your other episodes, if that can explain why I'm so confused.
@InteractiveBiology Thanks for the answer. Well I think that kinda answered my question, but I'm still a little bit confused. So the light enters our Rods at night, or in dark places, and then the procces begins, or does Rhodopsin first goes in contact in transducin at night. You helped me with some of the question, but in just 10 hours, I should tell something about Rods and Cornes. People in my class always puts "?" on everything (just like I do) I'm reallly glad I found your channel Subbed:)
@InteractiveBiology What are you planning to make your next video about ? I am asking because I have physiology right now and so far you have covered similar concepts. If that continues on I will have to check back more often.
@bizz76 Yes, we entirely use cones in bright light since there are very low cGMP levels in rods and no further hyperpolarization can be done. Also, the process is same for cones as well and in response to light, they also go through hyperpolarization. Only difference is cones have different type/s of opsins present. I think you are confusing cones with the Bipolar cells? I hope InteractiveBiology can cover a topic on Bipolar cells and their receptive field.
one major mistake, its 11-cis retinal. 11-cis retinol is an intermediate which is formed in the transformation from 11-trans retinal back to the light sensitive 11-cis retinal.
How would the process be in the cones? If the rods are hyperpolarized and not releasing neurotransmitters, how would it work out in the cones? Thanks!!
Cu99460 ... Em is the membrane potential, usually measured in volts. No doubt you will have seen a graph that shows an action potential/spike before, when there is depolarisation above a threshold value due to sodium ions raising the membrane potential. On this graph, it is a similar phenomenon, but because there is less sodium ions, the membrane potential becomes lower, which is known as hyperpolatisation..hope you see this in time for when you need it, I cannot reply inline on my tablet!
@mp5yourmp3 You are incorrect. While the central 300 µm of the fovea, called the foveola, is totally rod-free, there are actually some rods scattered amongst the cones in the rest of the fovea.
@SuperLLL Once the energy from the photon is used up, the retinol goes back to it's original configuration. It takes energy from the photons to keep it in the modified configuration.
I have a question that you told that in presence of light release of neurotransmitter slows down.then the signal do not pass to the brain then how we have see in presence of light?how we sense it?
According to my teacher quoting Lodish, PDE inhibitory sites are the gama subunits and not the alpha subunits. Alpha and beta subunits are the catalytic subunits of activated PDE which convert cGMP to GMP. Can you clarify?
@InteractiveBiology Yeah I understood that about they nearly have the same process. And that about the attractive young lady. Oh wait NOW I UNDERSTAND!!! I totaly misunderstood it. The normal form is when it's dark. I thought the normal form was in the day, that was why I couldn't really understand it. I was wondering how the light could stop the light, if you can say so. And now your comments make perfect sense.
Rails646 Cool, thx :D. BTW, do you know if other rhodopsins found in nature are part of different types of receptors such as ionotropic receptors? I'm trying to understand the mechanisms of optogenetics.
there are two types of bipolar cells, "ON" and "OFF". in the light, rods release inhibitory neurotransmitters, which activate the "ON" bipolar cells but inhibit the "OFF" cells, so the response is only sent through the "ON" route. in the dark, it's vice versa. rods don't release any more inhibitory neurotransmitters, "ON" cells are inactive, but "OFF" become depolarized and the signal is sent out through "OFF" route. now, bipolar cells can't affect rod cells, but horizontal cells can. they connect between rods and participate in lateral inhibition, a process when a neural signal from one rod cell is enhanced by hyperpolarising another rod cell next to it.
+Tanya Mejia Opsin is a protein and is a part of Rhodopsin. Rhodopsin is the visual pigment in rod cells. Production could, theoretically, be restricted through a transgenic animal model. However, this would probably produce a model that completely lacks Rhodopsin.
you according to lecture when no light present(night) cGMP gated channel is open letting in sodium and depolarise rods which then release glumate(excitatory nt) on bipolar cell then bipolar cell releases GABA (inh. nt) on optic nerve so we can not see. but when dim light present(few photons) all the opposite happens and we can see in night. but what happens in day(when lots of photon) to rods ? and please clarify lights in this vedio you mean day light or night
Really appreciate Leslie making all these videos. It helps me in my study of optometry courses and i have better understanding. It's very helpful for those student that lack of imagination. this video just help me to have a clear view and better understanding of the parts and structures
Excellent video series. Not certain why persons are being so critical, when they are clearly made to give students a general understanding. Thanks, You've helped sooo much!
You helped me get a distinction for my Advanced Physiology unit. God bless you! Thank you!
Nice video. I'm an ECE student doing biophysics. your videos really gave me insights into biological processes.
this was so well explained. There's hope that I might start to understand all of this. Thank you!
@InteractiveBiology Can't wait for that video. I remember this video was why I subscribed. You really saved my day!
This is really really good, keep making these videos. This helps a lot, because reading the textbook on stuff like this gets really wordy.
12 years ago and only 1 like lol
My professor posts really vague notes and I had no idea what's actually happening and this was so helpful.
Very coherent, well explained, good diagrams, very good breakdown of the processes. Only one mistake, though a major one and basic still does not take away from what a great video this is. Thanks!
@joinmebowser9000 What you see in this video is what happens in response to light. So light enters, hits the rods, and then this process (shown in the video) happens. It's very similar in the cones, but uses different pigments (not rhodopsin).
My professor referred me again to your meaningful contents...Thanks a lot,Leslie.
Make sure to thank your professor for me 😃
Great video, thanks! Helped a lot for my Systems Neuroscience exam.
im going to pass this section of my pscyh exam thanks to you
This was the one part of our unit that confused me so much (prof went through it super fast) thank you for this, it's helped me understand more. Thank you!!!!!
Got little confused at cGMP gated channels point...but then gradually I got it. thanks you.
Dr.Shams from Pakistan
u r great man...i really was in mess cramming of info worthlessly...know i understand tomorrow i have test..u've saved me..thanks!
@GoldenPhoenix223 Glad to know the video helped. Stay tuned for more Biology videos coming very soon!
Great Video. Thanks for your effort and time creating this!
I thought the fovea only contains cones ..
what is function of fovea.if it occurs more then what will do .that situation
I also
Our teacher says fovea has only cones not rodes
@joinmebowser9000 No such thing as a dumb question. Yes, we use rods to see at night, but even then - that's because light is entering our eyes. We can't see with light (even when it's relatively dark). Hope that helps answer your question.
"attractive young lady" - I nearly choked on my coffee. Very well done, thanks!!
@bizz76 I'm sorry, but Leslie won't be able to answer your question as he is busy with a lot of stuff. He'll be making more Biology videos for the site though tackling more systems and other topics, so stay tuned for more! :)
Thanks for the video, but you might want to correct your graph of membrane potential. Open cGMP-gated channels keep membrane potential relatively "depolarized" and permissive for glutamate release from terminal. Closing these channels causes an increase in membrane potential, not a decrease as drawn.
jim miller clarification, starting membrane potential is negative, so increase in membrane potential is more negative and graph, as drawn, is correct
@Ckaotenkind Well, we're glad to know you've gained something from it. We hope you aced your test. Stay tuned because we have new Biology videos coming very soon :)
thanks so much for your help I bet this is a very good explanation but I am so confused maybe I need to watch video more than once. Thanks again for your hard work and interest in educating the world :)
awesome! Now I can understand better about this topic. Clear and easy to understand!
I don't think it will complicate things, just chemically speaking there is a big difference and writing the wrong one down in an exam is not the best. If you just kept it as retinal throughout the video, then i would consider it a general introduction and wouldnt criticise. in all fairness, its great that things like this are available on youtube and that people take the time to upload them. i would keep it as retinal for simplicity and only mention the retinol etc in a more in depth video.
Great video! very simple explained. It helps me to understand my medical study about the eye. Thank youuuu soo much.
Sir I am very very thankful to you for clearing my concepts. Can you tell me if you have any video made on sympathetic and parasympathetic response.
Very clear and helpful! Thank you so much.
Very simply explained...
Great video...Thanx...
Appreciate your video! Nonetheless I wanted to inform you that what you said in minute 0:47 isn't quite correct from what I know. The foeva does not contain both cones and rods. The foeva only contains cones; thats why visual acuity is best there. Have an amazing day :).
Thanks for adding that. You're correct. What I said was wrong. I should've said that it has a lot of cones, but it doesn't have rods.
Thanks so much for this video, it has been so helpful.
At about 9:50 you mentioned a "depolarization" from cGMP gated-ion channels. but you also said that Na+ ions were leaving the cell, wouldn't this cause a hyperpolarization?
Yes it will cause Hyperpolarization, but the moment it happens, this polarization of membrane will release neurotransmitter into the synapse of the rods membrane and the bipolar neuron, thus impulse is generated to the occipital region for vision processing.
depolarization from cGMP causes Na+ to enter the cell via the ion-channels, not to exit
keep in mine that the bipolar neuron has on-center and off-center which works differently
I always thought that the rods and cones' resting state was a depolarized membrane potential, and they are constantly releasing NT onto the bipolar cells. Once visual transduction processes have been performed that constant stream of NT is shut off creating a change in membrane potential of the bipolar which can code for ON or OFF.
(NT = neurotransmitter)
Madjack
Your last comment is correct. Some Na+ ions are always leaving the cell, whether it's light or dark, due to the ongoing activity of the Na+/K+-ATPase, which pumps Na+ out and K+ in. On its own, this would cause the membrane potential to be set at approximately -70mV (which is the case for many neurons). However, in photoreceptor cells, the cGMP-gated Na+ channels allow Na+ ions to diffuse into the cell faster than they are being pumped out by the sodium-potassium pump, causing the cell to be depolarised in the absence of light.
I just got a little question. Aren't rods them we see with in the night? Then why does the procces begin when the light comes in, and not when it stops?
And sorry for my dumb question, but I just came to see about rods and cones, and I haven't seen any of your other episodes, if that can explain why I'm so confused.
There are no rods in the fovea
+Samantha Opara yep i agree (0.45)...only cone cells are mainly found in the fovea
ya in the fovea centralis there no rods only cones but in the maucla lutea there are many cones and a few of rods
thats true
@InteractiveBiology Thanks for the answer. Well I think that kinda answered my question, but I'm still a little bit confused. So the light enters our Rods at night, or in dark places, and then the procces begins, or does Rhodopsin first goes in contact in transducin at night. You helped me with some of the question, but in just 10 hours, I should tell something about Rods and Cornes. People in my class always puts "?" on everything (just like I do)
I'm reallly glad I found your channel Subbed:)
@InteractiveBiology What are you planning to make your next video about ? I am asking because I have physiology right now and so far you have covered similar concepts. If that continues on I will have to check back more often.
@Malikorous LOL. Not sure, but glad you are finding value in them. All the best!
This is perfect! Thank you!
@bizz76 Yes, we entirely use cones in bright light since there are very low cGMP levels in rods and no further hyperpolarization can be done. Also, the process is same for cones as well and in response to light, they also go through hyperpolarization. Only difference is cones have different type/s of opsins present.
I think you are confusing cones with the Bipolar cells? I hope InteractiveBiology can cover a topic on Bipolar cells and their receptive field.
Thanks you interactiveBiology.... What does 'Em' mean? just confused with the little graph at 10:30?
Yesterday, I am diagnosed for a ERG and confirmed that I have Cone-Rod Dystrophy... And I am here for searching for this...
one major mistake, its 11-cis retinal. 11-cis retinol is an intermediate which is formed in the transformation from 11-trans retinal back to the light sensitive 11-cis retinal.
thank you SO much from japan!
that was very helpful!
Opsin activated opsin activates transducin tranducin activates
phosphodiesterase cyclic GMP levels decrease gated Na+ channels close
neurotransmitter release decreases
How would the process be in the cones? If the rods are hyperpolarized and not releasing neurotransmitters, how would it work out in the cones? Thanks!!
Cu99460 ... Em is the membrane potential, usually measured in volts. No doubt you will have seen a graph that shows an action potential/spike before, when there is depolarisation above a threshold value due to sodium ions raising the membrane potential. On this graph, it is a similar phenomenon, but because there is less sodium ions, the membrane potential becomes lower, which is known as hyperpolatisation..hope you see this in time for when you need it, I cannot reply inline on my tablet!
@mp5yourmp3 You are incorrect. While the central 300 µm of the fovea, called the foveola, is totally rod-free, there are actually some rods scattered amongst the cones in the rest of the fovea.
@SuperLLL Once the energy from the photon is used up, the retinol goes back to it's original configuration. It takes energy from the photons to keep it in the modified configuration.
Thank you sooooo much what an amazing video!
I have a question that you told that in presence of light release of neurotransmitter slows down.then the signal do not pass to the brain then how we have see in presence of light?how we sense it?
Thankyou so much. This video was very helpful 😊
Ain't the alpha subunit of Transducin (G protein) which gets separated on conversion of GMP to GTP , activates PDE?
According to my teacher quoting Lodish, PDE inhibitory sites are the gama subunits and not the alpha subunits. Alpha and beta subunits are the catalytic subunits of activated PDE which convert cGMP to GMP. Can you clarify?
I concur
Which software did you use to make this beautiful video? 👍
what role does arrestin and Rhodopsin kinase play in phototransduction?
Wow this video helped me a lot and i really appreciate it... GOD bless you
Thank you so much, love your channel! Very helpful.
This video is very useful but there should be cis retinal/ retinene instead ogf retinol. Its a bit confusing, please make me correct if I am wrong...
@InteractiveBiology Yeah I understood that about they nearly have the same process. And that about the attractive young lady.
Oh wait NOW I UNDERSTAND!!! I totaly misunderstood it. The normal form is when it's dark. I thought the normal form was in the day, that was why I couldn't really understand it. I was wondering how the light could stop the light, if you can say so. And now your comments make perfect sense.
thank you so much! amazing how you made this so much simpler than the textbook !
Very interesting. This video alone prompted me to subscribe. Keep it up! :)
How does the retinal get back to its original position?
found it extremely helpful♥️
Thankyou sir.. 🙏🙏
It helps out me a lot... 🙂🙂
If rhodopsin works as a light-sensitive pigment, how do cones know what wavelenght be sensitive for?
Well first of all Rhodopsin is predominant in Rods not cones, and Photopsin is predominant in Cones.
Rails646 Cool, thx :D. BTW, do you know if other rhodopsins found in nature are part of different types of receptors such as ionotropic receptors? I'm trying to understand the mechanisms of optogenetics.
Nicely done.
I dont understand. Wouldnt the rod be releasing inhibitory neurotransmitters in its "on" state since the bipolar cell is off when the rod cell is on??
there are two types of bipolar cells, "ON" and "OFF". in the light, rods release inhibitory neurotransmitters, which activate the "ON" bipolar cells but inhibit the "OFF" cells, so the response is only sent through the "ON" route. in the dark, it's vice versa. rods don't release any more inhibitory neurotransmitters, "ON" cells are inactive, but "OFF" become depolarized and the signal is sent out through "OFF" route. now, bipolar cells can't affect rod cells, but horizontal cells can. they connect between rods and participate in lateral inhibition, a process when a neural signal from one rod cell is enhanced by hyperpolarising another rod cell next to it.
Your voice is just like Arnold Swazniger (dont mind about the spelling) and great lecture sir !
Waoooooo!!!!! Where have you been man. Thats soo helpful. Much appreciated
Emmanuel Korankye yeah💓
coursera rocks.Steve Joorden brought me here
me too
@InteractiveBiology I'm also glad I understand it now ;)
really informative video, good job :)
Great Work!!
Isn't it cis-retinal not retinol? Great video and very clear!
it's 11 cis retin
the rhodopsin is attached to the transducin before the light hits.
i want to ask admin.... is it the neurotransmitter released is the inhibitor (glutamate) ??
great video. but at the beginning you said the fovea contains a lot of rods and cones, which i believe is false. it ONLY contains cones.
How do you remove the other alpha with the system half reacted?
Oh its always on Na+ Regens
Really good. Had problems With the detachement of the retinal ^^
very helpful, thanks a lot
You're very much welcome
Does anyone know if there is a reaction during the rhodopsin cycle that would produce and emit light or perhaps a glow?
how is opsin produced and how could this production be restricted?
+Tanya Mejia Opsin is a protein and is a part of Rhodopsin. Rhodopsin is the visual pigment in rod cells. Production could, theoretically, be restricted through a transgenic animal model. However, this would probably produce a model that completely lacks Rhodopsin.
Sir , my eye vision is very low does it improve my vision with stem cell.
really a gud one...try making videos on center sorround receptive field too.
You are great!! Thank you soo much for the video! :D
u realy make biology fun thank u so much plz like this makde tuff topic easy for us
What are the 3 cone photo pigments ?
That sounds like a homework question 😉.
Check out this page on Wikipedia. It answers that question and more - en.wikipedia.org/wiki/Cone_cell
*Retinal (not retinol)...the molecule is an aldehyde, not an alcohol
Is this dark or light adaptation then? A little confused...
@Djalitana Probably the connection yes. Try again later and let me know
perfectly explained THANK YOU
thanks for the vid but my lecture says there are no rods in fovea
i think it's cis&trans retinal not retinol?!
yes, retinAl
Can you please help me. I would like to know what GDA is and what GTP is
thank you sir
this is helping me preparing for the first part examination in ophthalmology
wow..amazing..you me teacher of my friends....thank you so much leslie samuel
thank you, this was very helpful
you according to lecture when no light present(night) cGMP gated channel is open letting in sodium and depolarise rods which then release glumate(excitatory nt) on bipolar cell then bipolar cell releases GABA (inh. nt) on optic nerve so we can not see.
but when dim light present(few photons) all the opposite happens and we can see in night.
but what happens in day(when lots of photon) to rods ?
and please clarify lights in this vedio you mean day light or night