Photoreceptors (rods vs cones) | Processing the Environment | MCAT | Khan Academy

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  • Опубліковано 23 гру 2024

КОМЕНТАРІ • 73

  • @gavinh2614
    @gavinh2614 3 роки тому +13

    Please note that the discs inside a rod are NOT called optic discs. The optic disc is equivalent to the blind spot since this is where the optic nerve is exiting the retina. It's important to know that there are no rods or cones in the optic disc as well

  • @rawdonwaller
    @rawdonwaller 9 років тому +25

    as someone else commented: action potentials only arise from the ganglion cells.

  • @johntepp
    @johntepp 8 років тому +38

    rods and cones dont fire APs, just transmit graded potentials.

  • @edwinrelf8454
    @edwinrelf8454 11 років тому +82

    Rods and cones do not fire action potentials

    • @c00perz1
      @c00perz1 10 років тому +3

      Can you explain further, how do they convert this iforrmation

    • @iamjoshua
      @iamjoshua 10 років тому +17

      Jack Coupland They are actually always "on", continuously releasing the neurotransmitter glutamate to attached bipolar cells. They stop doing so when they become stimulated by photons. So this video is incorrect as Edwin points out. en.wikipedia.org/wiki/Photoreceptor_cell

    • @byronstrohm3887
      @byronstrohm3887 5 років тому +4

      Correct, they are constantly generating excitatory graded potentials in the absence of light, causing the release of inhibitory NT in the synapse between them and the bipolar cells they communicate with. In the presence of light, these graded potentials in the photoreceptors stop which stops the release of the inhibitory NT at the synapse. This causes the postsynaptic bipolar cell to depolarize. They release excitatory NT in the synapse between them (bipolar cell) and the Ganglion cell they are hooked up to. Ganglion cells then depolarize which turn into the optic nerve and an action potentials makes its way down the optic tract. Life is truly amazing

    • @Ispeaktruth18
      @Ispeaktruth18 4 роки тому +3

      Byron Strohm if you know all that why are you watching this video?

    • @francescakhamisa9757
      @francescakhamisa9757 4 роки тому

      true. only ganglion cells generate action potentials!

  • @zuhraaziz8225
    @zuhraaziz8225 9 років тому +13

    I don't know if Khan academy has already done this or not, but you should make a video on the visual pathways (Geniculostriate, tectopulvoinar, and Retinohypothalamic). It is a bit hard to understand just by reading about them from the textbook.

  • @savannahtallino8534
    @savannahtallino8534 8 років тому +7

    Looks like the video (at the end) is also incorrect about dark vs. light adaptation (they got it backward). Bummer. Was going to use this video to help my students but there's too many conflicting details and I don't want to confuse them.

  • @christiandorcaskisely3946
    @christiandorcaskisely3946 4 роки тому +2

    Thanks a lot ! Great video ! Well illustrated

  • @PhysiologyOpen
    @PhysiologyOpen 4 роки тому +3

    In rods the discs are not membrane-bound, they are free-floating..In cones, they are membrane-bound. Also as many people mentioned, rods and cones don't fire action potential

  • @adamjzimmer
    @adamjzimmer 7 років тому +31

    I spent a solid hour of searching to find this exact explanation, and then I read the comments and key parts are wrong?? If this is not accurate you should delete or edit the video. You're misinforming people. If you have other videos, you should fact check them and make sure you're correct when stating scientific facts.

    • @RxlredE
      @RxlredE 5 років тому

      Just correct what's the mistake

    • @Sora-ce1zx
      @Sora-ce1zx 5 років тому +14

      I think this is the reason why the comment section exists.
      Khan academy are not experts and not well paid. And it’s free to anybody.
      In a lot of Khan academy videos, mistakes are here and there, but we can’t blame them.
      Instead, we should just point it out in the comment section and support them.

  • @albertesquivel6545
    @albertesquivel6545 6 років тому +3

    You shouldn't use the terminology optic disks because that also refers to the optic nerve.

  • @b.bharathkumar7332
    @b.bharathkumar7332 2 роки тому

    worthy till now.....

  • @parakhmody1413
    @parakhmody1413 10 років тому +5

    "Rods and cones do not fire action potentials" ---Edwin Relf
    How do you respond to that?
    Also, isn't the slow recovery time due to pupil dilation/contraction?
    What I'm getting at is that isn't there a time limit(refractory period), which, once elapsed, any neuron will necessarily fire an action potential, regardless of what kind of neuron it is, given the right conditions(more permeability for Na+ than K+)?

  • @attractive5858
    @attractive5858 10 років тому +1

    this video was helped me! thanks a lot

  • @LegiRGomes
    @LegiRGomes 7 років тому +1

    Thanks for your explanation it really helped me a lot

  • @DannyMercer1993
    @DannyMercer1993 10 років тому +1

    That was excellent :)

  • @UHFStation1
    @UHFStation1 5 років тому

    Is it the shape of the cones that give us fine detail, and do certain retina diseases that damage fine detail alter the cones' shape?

  • @haroentmimi
    @haroentmimi 2 роки тому

    thank you so much

  • @mcmuffin1220
    @mcmuffin1220 9 років тому +1

    What is the difference between photopsin and iodopsin? My book says that cones contain iodopsin. Are they just two words for the same thing?

    • @sugarsugar4410
      @sugarsugar4410 8 років тому +2

      +Mac Muffin photopsin is a more specified kind of iodopsin !

  • @zachklepper
    @zachklepper 3 роки тому

    What is the method to determine how many rods/cones there are?

  • @camilacruz1937
    @camilacruz1937 10 років тому +1

    Great explanation!Thank You!

  • @abiabisiscutty9221
    @abiabisiscutty9221 4 роки тому

    Tq

  • @passer-by8732
    @passer-by8732 2 роки тому

    merci

  • @iwillbeback8686
    @iwillbeback8686 4 роки тому

    3:13 function

  • @MadTwatter
    @MadTwatter 8 років тому +6

    *Re-ina*

  • @paradiseentertainment166
    @paradiseentertainment166 2 роки тому

    What are the 3 photopigments in cone ?

  • @krugertiaantk
    @krugertiaantk 8 років тому

    great!!!

  • @keegancan
    @keegancan 4 роки тому

    So, if we run inside after playing sports to get a cup of water maybe our eyes adjust better to lighting that changes just a little bit compared to going to a lighted room to a darker room?

    • @simranyadav9275
      @simranyadav9275 4 роки тому

      Ya most probably because even the iris needs to adjust it's size according to the light intensity.

  • @cosycheung
    @cosycheung 10 років тому

    Thanks for sharing

  • @orchidsrain
    @orchidsrain 11 років тому

    this really helped ! Thankyou

  • @varunjoshi8251
    @varunjoshi8251 10 років тому

    Thank you :-)

  • @zamzam515
    @zamzam515 6 років тому +3

    it’s cone shaped: draws a triangle

    • @youreanonshareer
      @youreanonshareer 5 років тому +5

      zamzam are you dumb...?

    • @Distruct10
      @Distruct10 4 роки тому

      what do you think a cone looks like from the side

    • @zamzam515
      @zamzam515 4 роки тому +1

      youreanonshareer I was going through it that time period.

    • @zamzam515
      @zamzam515 4 роки тому +1

      SugarNaught pls I was just a dumb sophomore let me live

    • @Distruct10
      @Distruct10 4 роки тому +2

      @@zamzam515 lol its ok glad you got through it

  • @mintmonkey1017
    @mintmonkey1017 9 років тому

    Please could I have a list of keywords for the parts?!📚

  • @Hellohellonamehere
    @Hellohellonamehere 5 років тому

    Only ganglion cells fire, correct?

  • @khal2652
    @khal2652 3 роки тому

    Cones and rods are neurones not nerves right???

  • @perrymiddaugh8614
    @perrymiddaugh8614 3 роки тому

    Taped on this and through it was the Blue Man Group song😂

  • @barbaricrawr4190
    @barbaricrawr4190 3 роки тому

    Wouldn't the cells be called neurons and NOT nerves? Nerves are bundles of axons...

  • @bellpepper3166
    @bellpepper3166 8 років тому

    You can learn this from blue man group.

    • @frosty5090
      @frosty5090 7 років тому

      Dubbers Voicemai has

  • @ghkageyama
    @ghkageyama 4 роки тому

    Rods and Cones do not generate action potentials.

  • @KiranSingh-es2ot
    @KiranSingh-es2ot 4 роки тому

    Why do you keep saying “optic discs”? Optic discs actually have a very defined meaning in optic terminology. Optic discs refer to the optic nerve head (ONH). You’re misleading people by calling the photoreceptor discs of rods “optic discs”. It’ll get confusing for people when textbooks refer to the optic discs for other explanations not related to photoreceptors

  • @BostonPower
    @BostonPower 2 роки тому +1

    ABRUPT ENDING MUCH? LOL

  • @vechniyyt5778
    @vechniyyt5778 Рік тому

    МАШУКА МАШУКА Т

    • @9-volt247
      @9-volt247 Рік тому

      Huh? I can't understand that language! It may be Russian that you're speaking. I only speak English and Spanish.

  • @holyspecs
    @holyspecs 6 років тому +1

    Poda

  • @tachtoucho
    @tachtoucho 7 років тому

    everything he said is false !

  • @milindpathak-here
    @milindpathak-here 2 роки тому

    And many say , God doesn't exist !!

    • @9-volt247
      @9-volt247 Рік тому

      GOD DOES EXIST!! WHERE IS YOUR COMMON SENSE?! 🤬🤬🤬

  • @Juhcamposc
    @Juhcamposc 4 роки тому +2

    What a great explanation! Thank you

  • @meenasalve9146
    @meenasalve9146 2 роки тому

    Thank you so much

  • @moongirl6128
    @moongirl6128 3 роки тому +1

    What a great explanation! Thank you