The phototransduction cascade | Processing the Environment | MCAT | Khan Academy

This explains phototransduction cascade which is critical to our sense of vision. By Ronald Sahyouni. Created by Ronald Sahyouni.
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[@suhheecook4910]

PhD student in biomedical engineering taking my last qualifying course ever... medical physiology. you're saving my life!

[@katharinalysy1518]

"We'll just give it kind of a neutral face because it's ... bipolar." :'D I love this, makes me remember things way better!

[@NicMNeves]

hey, i'd like to amend what you said about the naming of the bipolar cells, its actually not "bipolar" because it's on or off, its actually referencing the structure of the cell (it has two poles). This differentiates it from a unipolar cell, which is like a rod with only a single pole, transmitting a signal in 1 direction.

[@casslovesyhuu]

This was such a great help! My physiology lecturer literally had no idea when he was teaching me this... Thank you! :)

[@S_a_Z_m]

Best part 0:49 but even without it, it's still a good video.

[@JealousyIsMadness]

Thank you!!!!! I'm trying to absorb information for my Neuro final, this was super helpful

[@sofiab3829]

You made this more clear than more neurophysiology teacher in optometry school! Thanks a ton

[@MsChaosbutterfly]

One error: These cells do not produce action potentials. (Neither do bipolar cells.)

[@SoDrigh]

So how are signals transmitted?

[@jessmason2161]

***** Graded Potentials. More efficient transmission over short distances.

[@croin6020]

Amacrine cells are the first once who produce an ap

[@halwa8128]

true. when he said "action potential", i thought i misread my book. it's transmitted by the graded potential. correct me if im wrong

[@guminjrng5610]

They produce graded potential

[@lensmaticoptical4083]

Millions of claps for you Sir. You are a real teacher..... Thank you

[@offsp25]

Good presentation... i have more understanding point from you. Thank you.

[@trisch7499]

This is exactly what i need right now! Thank you!

[@marianahozahoza6496]

With khanAcademy it feels like I found a treasure . 🗽 Thx a lot !

[@fatimah9815]

Great Video and very clear explanations! Thank you very much

[@BenBezpark]

Thanks so much for the video. Was a great help glad to have you around :)

[@itskittyme]

Just another beautiful example of Intelligent Design.

[@yaytheo3289]

Really nice explanation, but the rod does not hyperpolarise only due to the Na channels being blocked, but also due to K channels remaining open and pumping K outside the cell. Other than that, great! ;)

[@zas881]

Very clear explanation! Thank you so much. Effort appreciated

[@Shyam-wz5ro]

Hats off ...great video. Very thankful

[@existentia1krisis]

I have to turn down most videos because they're super loud, but with this one, I had the volume turned up all the way on youtube and on my computer settings and still had to turn on subtitles. Other than that, great video!

[@stevenk113]

The 11-cis conformation drawing is a little misleading. The branch should be angled downward after carbon 11 to indicate it being "bent"

[@jimmiller8875]

maybe someone mentioned this in previous comment (apologies if so): opsins don't have seven subunits, they have seven transmembrane helices

[@Sally6861]

Thank you! It makes more sense now!

[@smileki89]

do the same happen for the cones?

[@TadanoCandy]

Thank you for a very helpful video :)

[@MrPridizzle]

Thank goodness for 1.75x playback speed.....

[@kaijaeseri8990]

Thank you for the elaborate explanation

[@jiedeng3934]

Thank you!!

[@jazminbrantley3325]

Great video. Very helpful.

[@nimraaslam7715]

Thank you so very much!

[@selenozmen2251]

Nice way of telling a boring subject, thank you very much for the explanation :))) Now that I understand the mechanism, I don't have to memorise it ;)

[@Safestreet]

Very nicely explained.

[@keighleyhayes]

let's give him a little smiley face because he's happy

[@karedo9924]

you sir rock!

[@slobberdan8428]

Beautifully explained thanks

[@robertryansantamaria75]

Very nice... :) additional input, metarhodopsin II activates transducin...

[@anamika4088]

U made it really easy to visualize

[@oop8599]

thankyou so much :D really easy to understand

[@evanpham7881]

Actually crying in happiness!

[@itstheannas]

Explanation so clear I can finally sense my cones when ma man changed the colors of his markers

[@acevedoyadi]

Thank you.

[@txaitxaitxai]

the name "rhodopsin" is actually coming from the latin for "red" (rhodo-) not because it's in the rods. That's just a way to remember it.

[@laured7593]

THank you so much for the video, it helped me so much! I do belive though that the word "rhodopsine" does not come from "rods" but from the Greek "rhodon" meaning "pink", but I am sure someone mentioned it already.

[@jonathanklein1133]

Yup, and the protein in cones isn't called conopsin it's called iodopsin

[@guminjrng5610]

Not pink its purple

[@SkyZone57]

I just love you

[@mahtabfotovat4908]

Hello, thank you for this amazing video, I have both a question and and a suggestion, Q: do you mean outer nuclear layer and inner plexiform layer by mentioning two types of bipolar neurons or actually there two distinct types of them? And my suggestion is it would be nice to have clarification when when have Rhodopsin kinase activity and its association with reduced activity of transducin also maybe the role of arrestin, thank you

[@user-iu7yu6us7i]

Like this can you explain what happens in cone cell

[@miss0noodle]

Anyone else hear sweet birdie chirps around 7:25?

[@debbee5898]

I've read that there are 'on-centre bipolar cells' and 'off-centre bipolar cells', correct? When light hits rods, the off-centre bipolar cell depolarizes and releases a neurotransmitter. when no light= rod on= off-centre bipolar cell depolarizes and releases neurotransmitters. My question is which neurotransmitters the bipolar cells release and if we need to know that on the MCAT.

[@MarttyLovato]

i love smiley faces on rods and cones

[@queenofunderland]

Many of us , like me , turn to be crazy 'bout it

[@MsTommyknocker]

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??

[@jimmiller8875]

MsTommyknocker it could, but doesn't; vertebrate photoreceptor cells (rods and cones) release glutamate from end opposite to outer segment to bipolar cell, so in dark they are "on"; cGMP-regulated channels in outer segment essentially "leak" sodium and calcium into outer segment and keep the cell relatively "depolarized" in dark (so glutamate is released), closing these channels decreases "leak", makes the cell more "polarized" (membrane potential more negative) and glutamate release is decreased

[@intj1434]

^What I learned is that, you know how the video mentions that there are 2 types of bipolar cells? On-bipolar cells have mGLuR6 receptors (G-protein coupled metabotropic receptors) on the terminal where they synapse with the photoreceptors. Off-bipolar cells have ionotropic receptors on the terminal. Photoreceptors always release glutamate as their neurotransmitter. mGluR6, when bound to glutamate, actually closes the cation channels on the On-bipolar cells, hyperpolarising it. So even if the photoreceptor is depolarised, On-bipolar cell coupled with it will be hyperpolarised. Ionotropic receptors on the other hand allows cation influx into off-bipolar cells, depolarising it. Which one of these happens depends on the amount of glutamate released by the photoreceptors (less if the rod is off, more if it's on) and what type of bipolar cell is coupled with it.

[@halwa8128]

does the cone cell have the same cascade as well?

[@_adi_dev_]

Rhodopsin isn't named for what type of cell its in, it was named for its colour

[@user-kk5ep8sk6z]

How does rods have power to convert it? How does the process take place?

[@IK-fg4gw]

No mention of opsin?

[@tova6273]

Great video. One thing I don't get- is phosphodiesterase another name for cGMP? Or are they different things?

[@Vimarphil]

+Tova They're different : phosphodiesterase is activated by the alpha subunit of the rhodopsin, and then takes cGMP from intracellular milieu to turn it into GMP ! I hope I helped and that there's no english mistakes !

[@NLSoulja99]

cGMP (cyclic guanosine monophosphate) and PDEs (phosphodiesterases): PDEs are those enzymes that catalytically convert the so called "second messenger" cGMP to GMP (by breaking a phosphodiester bond). When cGMP levels are elevated, PDEs are then responsible for decreasing its levels back to normal, thereby being responsible for its regulation. It's also interesting to know that the actual sex drug Viagra (Sildenafil) is just an inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5). This enhances the vasodilatory effects of cGMP in the corpus cavernosum. Cyclic GMP has literally dozens of functions, apart from vision and erectile (dys)function, also is implicated in other cellular functions, like proliferation, apoptosis etc.

[@monday2471]

what's the purpose of having on and off bipolar cells?

[@adityarizqi8429]

Please help me, how can or why the Alpha cell come over to bind with phospodiester?

[@pfln]

isnt phosphodiessterase an enzyme?

[@nadaid8449]

I need to understand how the rod work please anybody can help my it's confuse for my

[@lorrainebennett9187]

laymans terms my rods are in an umbrella dome and gold whats the meaning

[@EDUARDO12348]

at 4:40 did anybody else hear birds or am I just studying too much?

[@oviaxanax5645]

EDUARDO12348 i did mate

[@BakrAli10]

@@oviaxanax5645 yeah we are studying too much

[@pfln]

And arent the ganglion cells the one that initiate action potentials, not bipolar cells? Im just making sure b/c i have a physio test thursday and im panicing HEEHOOHEEHOO

[@rachelwhipple677]

what about scotopsin?

[@ShiranaiNeko]

It's a good video but you didn't really explain why it's called a cascade

[@francoisjeffery1606]

reIHnal

[@fadisoltan5113]

fucking life saver

[@user-gi2vc5xg5f]

자막애 한국어 지원부탁드립니다.

[@purplestains7426]

very basic video... missed out on many details thumbs down!