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060 Hemoglobin and the Oxygen-Dissociation Curve

Ever wonder how the oxygen binds to our blood cells and sent to the different parts of our body? Watch and learn with Leslie as he explains how this happens and uses the Oxygen-Dissociation Curve to describe this event.

Have fun!

Transcript of Today’s Episode

Hello and welcome to another episode of Interactive-Biology T.V. where we’re making Biology fun! My name is Leslie Samuel and in this episode, Episode 60, I’m going to be talking about hemoglobin and what’s called the oxygen-dissociation curve. So, let’s get right into it.

We’ve already done an introduction to the respiratory system and we’ve shown how the heart beats and sends the blood. When the right ventricle sends the blood, it sends it to the lungs that comes back to the left atria and then, the left ventricle pumps and that sends the blood through the rest of the body.

We’ve also looked in the lungs and seen how we have the trachea going into the bronchi and then that splits off into the bronchioles, and as you can see here, that gives us the alveoli and it’s in the alveoli where we have the exchange between the oxygen coming into the bloodstream, via the capillaries that we have here, and the carbon dioxide leaving the capillaries going into the lungs and being sent from the body.

Now, when the blood comes in here, it is picking up oxygen, and the type of blood cells that are picking up the oxygen, would be the red blood cells. Here you can see a picture of a few red blood cells, of course, it’s simplified. It’s not showing the white blood cells or anything else. It’s just showing the red blood cells and these are the blood cells that pick up that oxygen.

In the red blood cells, we have special molecule. That molecule is called hemoglobin. You can see a three-dimensional image here of the structure of hemoglobin so, this is, (let me write it here), hemoglobin. This molecule, it’s actually a protein, and this protein is the protein that is responsible for picking up the oxygen.

Now, let’s go into a little more detail. You can see here, that we have these four structures. Those four structures are called, (let’s do that in blue), those are heme groups. All right, so these are the four heme groups. The special thing about these heme groups is that those are the parts where the oxygen is attracted, so, we have O2 that actually comes and binds to the heme groups. As you would imagine since we have four heme groups, we can take a total of four oxygen molecules. So, this is one oxygen molecule here, and we can have another oxygen molecule here, here, and also here. So, this hemoglobin molecule once again, has a capacity to hold four oxygen molecules.

What’s interesting about the hemoglobin is that whenever one oxygen binds to a heme group, that causes the entire hemoglobin structure to undergo a conformational change so, basically changing the site of the molecule whenever one oxygen binds. As you can see here, this is the heme group but, there’s stuff around on it, and you can imagine that it would be relatively hard for the oxygen to get in there and find the right spot.

However, when one binds, it causes a change which opens it up a little bit to make it a little easier for another oxygen to come in and bind. And, when that other oxygen comes in and bind, it causes another conformational change, making it easier for another oxygen to come and bind and, once again, once that oxygen comes and binds here, it makes it easier for another oxygen to come in here and bind to it. So, in other words, as it starts taking up oxygen, it makes it easier for it to take up more oxygen. And then, of course, the opposite will be true. If we have a hemoglobin molecule that has four oxygen attached and, for some reason it gives up one oxygen, that’s going to cause a change that makes it a little harder for the other oxygen to bind. In other words, it becomes easier for oxygen to leave. So, as oxygen leaves, it’s easier for more to leave; as oxygen binds, it makes it easier for more oxygen to bind.

As a result of this, we get a relationship that is shown in this oxygen-dissociation curve. And, what you can see here is, (we’re going to be looking at this blue line) and, as you can see here, it’s not a linear relationship. In other words, as the amount of oxygen increases, so here, we’re showing the pressure of oxygen, as the pressure of oxygen increases in the environment that the hemoglobin is in, you’re going to get more binding, making it easier for more to bind, making it easier for more to bind, and the graph is going to increase faster as you’re going to the right where you have an increased partial pressure of oxygen.

Not a linear relationship but, as some binds it becomes easier so, more bind faster and it becomes easier and it gets faster and faster until, of course, it reaches to where it’s getting saturated and, it dies off.

Now, you might be wondering why it’s not just four-levels since we only have four binding spots for the oxygen, the four heme groups. However, this is not looking at one hemoglobin molecule. This is looking at a bunch of hemoglobin molecules in a bunch of red blood cells and, overall, as some starts binding, it makes it easier and easier so, it’s going to increase faster and faster until it reaches to the saturation and then, it’s going to slow down when it reaches its full saturation.

Also, as you come in this direction, as the pressure of oxygen decreases, and oxygen starts to leave, here it’s leaving slowly but, as it starts to leave more, it’s dropping down faster, and faster, and faster, until all of the oxygen is gone.

So, this is the oxygen-dissociation curve showing once again, as you pick up oxygen, it makes it easier for oxygen to be picked up, so here it starts slow and it goes faster and faster and faster and as you release oxygen, it makes it easier for oxygen to leave and then, that goes down faster and faster. This is called the oxygen-dissociation curve.

That’s pretty much it for this video. If you want to see more videos like this and check out the other resources we have available, visit the website at www.interactive-biology.com.

That’s it for this video and I’ll see you on the next one.

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Leslie Samuel is the creator of Interactive Biology. His mission is to use this site to Make Biology fun for people all over the world.

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Leave An AWESOME Comment

141 Responses to “060 Hemoglobin and the Oxygen-Dissociation Curve”

  1. kakaonkaka June 7, 2011 at 6:57 pm #

    nice comprehensive resp physio review for me! thx a lot!

  2. kakaonkaka June 7, 2011 at 6:57 pm #

    nice comprehensive resp physio review for me! thx a lot!

  3. InteractiveBiology June 7, 2011 at 6:58 pm #

    @kakaonkaka Glad it helped. Stay tuned for more :)

  4. InteractiveBiology June 7, 2011 at 6:58 pm #

    @kakaonkaka Glad it helped. Stay tuned for more :)

  5. Hiko June 7, 2011 at 9:01 pm #

    Learnt something today! thanks

    • Lrsamuel June 8, 2011 at 6:51 am #

      You are Very Much Welcome. Always glad when someone learns :)

  6. Zendiya1 June 8, 2011 at 9:24 am #

    thank you so much Lesile..it helped a lot.

  7. Zendiya1 June 8, 2011 at 9:24 am #

    thank you so much Lesile..it helped a lot.

  8. InteractiveBiology June 8, 2011 at 10:03 am #

    That’s awesome. Glad it helped. Stay tuned for MANY more :D

  9. InteractiveBiology June 8, 2011 at 10:03 am #

    @Zendiya1 That’s awesome. Glad it helped. Stay tuned for MANY more :D

  10. InteractiveBiology June 8, 2011 at 10:03 am #

    @Zendiya1 That’s awesome. Glad it helped. Stay tuned for MANY more :D

  11. Shrikharan June 8, 2011 at 3:26 pm #

    Dear Leslie

    I think I must correct you. You were not very clear on the interpretation and the proper message offered by the O2 dissociation curve. I am a doctor and O2 dissociation curve is a very important component of respiratory physiology, and understanding of the diseases of the lungs.

    The real purpose of the sigma shaped O2 dissociation curve is to illustrate one important point. For the hemoglobin (Hb) to be saturated fully with O2 at the alveolar end, there must be a PO2 of 75 -100 mm Hg.

    At lower PO2, the Hb will become deoxygenated. To repeat PO2 > 75 mm Hg encourages saturation of Hb where else when PO2 is <75 encourage desaturation of Hb. This is how O2 is transported and delivered to the tissues.

    At the tissue level, where the PO2 is low makes the Hb to become deoxygenated and thus deliver the O2 to the tissue. This is how Hb does its function. It must capture O2 when PO2 is high (at alveolar level) and release the O2 when PO2 is low (at tissue level).

    The real message of the O2 dissociation curve is that at the alveolar level we have to maintain a good PO2 (75- 100mmHg) otherwise, Hb cannot be saturated and thus fails in its O2 transporting ability. O2 is poorly soluble in plasma and thus depends on the Hb to carry it to the tissues.

    Now see the graph again. According to the graph once PO2 drops to below 70 then it reaches a slippery slope and with slight decrease of the PO2 thereafter there is a rapid desaturation of HB (at the alveolar level) and loses its O2 carrying capacity and there is severe O2 lack/starvation by the tissues. PO2 at alveolar level can get affected by breathing O2 lacking air or due to pathology or disease of the lungs and proper gas exchange cannot take place to maintain a good PO2 (>75mmHg) so proper oxygenation of the Hb can take place to produce Oxyhemoglobin.

    This is the real message of the O2 dissociation curve – to see that PO2 does not drop below 75, and if you do, you will go down a slippery slope where a small drop of PO2 will produce a drastic drop in the O2 Saturation.

    • Lrsamuel June 8, 2011 at 3:57 pm #

      Hi there,

      Is that really a correction of what I said in the video? Or does it just look at it from a different perspective? You are right. That would’ve been a good thing to add in the video. However, that’s part of the reason why I have comments enabled. So that people could contribute what they know to what I put here.

      Do you think I said something that was wrong in the video? I’d like to know your answer to that.

      • Shrikharan June 8, 2011 at 8:52 pm #

        I think you are not really ‘wrong’ in what you said.

        You missed the main point behind the Sigma shape of the graph. Hb needs the high PO2 to saturate it. Below a point, a small drop in the X-axis produces a remarkable drop in the Y-axis.

        The Sigma has three legs, a horizontal, then a steep oblique and then a horizontal leg.

        This is my understanding. I am a doctor but not really a medical physiologist.

  12. eddieyou1018 June 30, 2011 at 5:39 am #

    good stuff yet annoying voice

  13. InteractiveBiology June 30, 2011 at 9:46 am #

    @eddieyou1018 Oh, you poor guy. Having to listen to my annoying voice, lol.
    It’s really easy though. All you have to do is not watch the videos, and
    everything will be ok. You won’t have to deal with such an annoying voice.
    All the best :D

  14. InteractiveBiology June 30, 2011 at 9:46 am #

    @eddieyou1018 Oh, you poor guy. Having to listen to my annoying voice, lol. It’s really easy though. All you have to do is not watch the videos, and everything will be ok. You won’t have to deal with such an annoying voice. All the best :D

  15. InteractiveBiology June 30, 2011 at 9:46 am #

    Oh, you poor guy. Having to listen to my annoying voice, lol. It’s really easy though. All you have to do is not watch the videos, and everything will be ok. You won’t have to deal with such an annoying voice. All the best :D

  16. olb852 August 3, 2011 at 4:12 pm #

    just ignore that asshole complaining about your voice. this is great.

  17. olb852 August 3, 2011 at 4:12 pm #

    just ignore that asshole complaining about your voice. this is great.

  18. InteractiveBiology August 3, 2011 at 4:26 pm #

    @olb852 Hey, everyone’s entitled to their own opinions :)

  19. InteractiveBiology August 3, 2011 at 4:26 pm #

    @olb852 Hey, everyone’s entitled to their own opinions :)

  20. InteractiveBiology August 3, 2011 at 4:26 pm #

    Hey, everyone’s entitled to their own opinions :)

  21. teddyasok August 3, 2011 at 9:17 pm #

    Above all, thank you for the help Leslie. It helps me a lot. God bless!

  22. InteractiveBiology August 3, 2011 at 9:33 pm #

    @teddyasok Glad to know it helps. All the best with your studies. Many more
    coming, so stay tuned!

  23. InteractiveBiology August 3, 2011 at 9:33 pm #

    @teddyasok Glad to know it helps. All the best with your studies. Many more coming, so stay tuned!

  24. InteractiveBiology August 3, 2011 at 9:33 pm #

    Glad to know it helps. All the best with your studies. Many more coming, so stay tuned!

  25. Rathana San August 25, 2011 at 5:38 am #

    Iron is necessary to make hemoglobin. Don’t forget Iron in your diet.

  26. Rathanasan August 25, 2011 at 5:38 am #

    Iron is necessary to make hemoglobin. Don’t forget Iron in your diet.

  27. Rathanasan August 25, 2011 at 5:38 am #

    Iron is necessary to make hemoglobin. Don’t forget Iron in your diet.

  28. m0elnaggar September 22, 2011 at 3:49 pm #

    @eddieyou1018 Fasc-austic lol

  29. m0elnaggar September 22, 2011 at 3:49 pm #

    Fasc-austic lol

  30. Kevin Sauntokhee November 23, 2011 at 6:42 am #

    its heam group

  31. MrKelvinatorboy November 23, 2011 at 6:42 am #

    its heam group

  32. 0326hkim November 24, 2011 at 2:34 am #

    !!!! Remember everyone….pH can also be Hydrogen Ion. the arrows would
    just be the opposite. High pH = low H and vice versa !!!!!!! Just in case
    your exam comes out tricky like that.

  33. 0326hkim November 24, 2011 at 2:34 am #

    !!!! Remember everyone….pH can also be Hydrogen Ion. the arrows would just be the opposite. High pH = low H and vice versa !!!!!!!

    Just in case your exam comes out tricky like that.

  34. nuzzy December 5, 2011 at 9:41 pm #

    you just make everything so easy ..thank youuuuuuuuuuuuuuuuuuuuu!

  35. Anna32071 December 5, 2011 at 9:41 pm #

    you just make everything so easy ..thank youuuuuuuuuuuuuuuuuuuuu!

  36. InteractiveBiology December 6, 2011 at 9:57 am #

    @Anna32071 You’re very much welcome :) Stay tuned for more Biology videos!

  37. InteractiveBiology December 6, 2011 at 9:57 am #

    You’re very much welcome :) Stay tuned for more Biology videos!

  38. InteractiveBiology December 6, 2011 at 2:57 pm #

    You’re very much welcome :) Stay tuned for more Biology videos!

  39. Tinkerbell1554 December 10, 2011 at 2:15 pm #

    this is great!!!!!!!!!!!!!!!!!!! It’s so easy!!!! although I’m german I can understand you better than my teacher.

  40. Tinkerbell1554 December 10, 2011 at 7:15 pm #

    this is great!!!!!!!!!!!!!!!!!!! It’s so easy!!!! although I’m german I can understand you better than my teacher.

  41. InteractiveBiology December 11, 2011 at 1:12 am #

    @Tinkerbell1554 :) Thank you! Glad you got something out of it. We have more Biology videos in the website, and more to be added so, please stay tuned for more!

  42. InteractiveBiology December 11, 2011 at 1:12 am #

    :) Thank you! Glad you got something out of it. We have more Biology videos in the website, and more to be added so, please stay tuned for more!

  43. InteractiveBiology December 11, 2011 at 6:12 am #

    :) Thank you! Glad you got something out of it. We have more Biology videos in the website, and more to be added so, please stay tuned for more!

  44. DiyaBabyee December 27, 2011 at 1:15 pm #

    Don’t you spell it like heam and heamoglobin?

  45. DiyaBabyee December 27, 2011 at 6:15 pm #

    Don’t you spell it like heam and heamoglobin?

  46. othoooo December 27, 2011 at 8:23 pm #

    wooooooow :) this is greaaaaaaaat vidoe man.. i ve biolgy exam in jan and i’m so glad to find such video >> i’m going to watch the rest :) thank u indeed mate

  47. othoooo December 27, 2011 at 8:23 pm #

    wooooooow :) this is greaaaaaaaat vidoe man.. i ve biolgy exam in jan and i’m so glad to find such video >> i’m going to watch the rest :) thank u indeed mate

  48. othoooo December 28, 2011 at 1:23 am #

    wooooooow :) this is greaaaaaaaat vidoe man.. i ve biolgy exam in jan and i’m so glad to find such video >> i’m going to watch the rest :) thank u indeed mate

  49. kerrie337 December 29, 2011 at 10:35 am #

    @DiyaBabyee nope its haemoglobin

  50. kerrie337 December 29, 2011 at 10:35 am #

    nope its haemoglobin

  51. kerrie337 December 29, 2011 at 3:35 pm #

    nope its haemoglobin

  52. pinappleexpress45 January 2, 2012 at 9:28 am #

    haemoglobin and haem groups good video though

  53. pinappleexpress45 January 2, 2012 at 9:28 am #

    haemoglobin and haem groups good video though

  54. pinappleexpress45 January 2, 2012 at 2:28 pm #

    haemoglobin and haem groups good video though

  55. WoWGuildVids January 10, 2012 at 2:28 pm #

    brilliant video

  56. WoWGuildVids January 10, 2012 at 7:28 pm #

    brilliant video

  57. sweetmeme1987 March 12, 2012 at 7:32 am #

    this is life saving. thank you a lot

  58. Omnia Khalid March 12, 2012 at 11:32 am #

    this is life saving. thank you a lot

  59. Omnia Khalid March 12, 2012 at 11:32 am #

    this is life saving. thank you a lot

  60. LilSayWhat March 12, 2012 at 2:59 pm #

    Actually, it is very difficult for the fourth oxygen molecule to diffuse in and associate with the last available haem group.

  61. LilSayWhat March 12, 2012 at 6:59 pm #

    Actually, it is very difficult for the fourth oxygen molecule to diffuse in and associate with the last available haem group.

  62. newlynappynat March 19, 2012 at 8:35 pm #

    Bless you for doing this, love your voice and find that you seem to make the most sense for me on YT. great job!

  63. snow12367 March 20, 2012 at 12:30 am #

    thankssss

  64. newlynappynat March 20, 2012 at 12:35 am #

    Bless you for doing this, love your voice and find that you seem to make the most sense for me on YT. great job!

  65. snow12367 March 20, 2012 at 4:30 am #

    thankssss

  66. topspinserve94 March 28, 2012 at 2:31 pm #

    Is the haemoglobin inside the red blood cell or is it just floating inside the blood plasma, if its inside the red blood cell doesn’t that lengthen the diffusion pathway making it less effective at picking up oxygen. Great video by the way it really helped.

  67. topspinserve94 March 28, 2012 at 6:31 pm #

    Is the haemoglobin inside the red blood cell or is it just floating inside the blood plasma, if its inside the red blood cell doesn’t that lengthen the diffusion pathway making it less effective at picking up oxygen. Great video by the way it really helped.

  68. TheTackyGirl April 1, 2012 at 11:23 pm #

    AMAZING. Thank you.

  69. TheTackyGirl April 2, 2012 at 3:23 am #

    AMAZING. Thank you.

  70. Jacob920826 April 4, 2012 at 11:47 pm #

    Thanks for your vid! It makes so much easier to study! :D
    Regards from Mexico city

  71. Jacob920826 April 5, 2012 at 3:47 am #

    Thanks for your vid! It makes so much easier to study! :D
    Regards from Mexico city

  72. machacoification April 5, 2012 at 11:55 am #

    that’s it my lecturer is a cunt

  73. marleyJJJ1 April 5, 2012 at 12:50 pm #

    You spelt Haemoglobin wrong.

  74. machacoification April 5, 2012 at 3:55 pm #

    that’s it my lecturer is a cunt

  75. marleyJJJ1 April 5, 2012 at 4:50 pm #

    You spelt Haemoglobin wrong.

  76. Babyxcakes1 April 9, 2012 at 9:24 am #

    This was the most useful video ever. I have recently started my degree and have never understood this concept so well as I have today! 10 star! Fantastic!!

  77. Babyxcakes1 April 9, 2012 at 1:24 pm #

    This was the most useful video ever. I have recently started my degree and have never understood this concept so well as I have today! 10 star! Fantastic!!

  78. Lightestin April 23, 2012 at 3:19 pm #

    Thank you so much!!
    This is so easy to understand compared to my AS book!

  79. Lightestin April 23, 2012 at 3:19 pm #

    Thank you so much!!
    This is so easy to understand compared to my AS book!

  80. Lightestin April 23, 2012 at 7:19 pm #

    Thank you so much!!
    This is so easy to understand compared to my AS book!

  81. fight4urpointofveiw May 7, 2012 at 1:38 pm #

    Spelt ‘Haemoglobin’ not ‘Hemeglobin’ apart from that very helpful :)

  82. fight4urpointofveiw May 7, 2012 at 1:38 pm #

    Spelt ‘Haemoglobin’ not ‘Hemeglobin’ apart from that very helpful :)

  83. nonoooooooooo1 May 11, 2012 at 11:17 am #

    U r the BEST ! thank u

  84. nonoooooooooo1 May 11, 2012 at 11:17 am #

    U r the BEST ! thank u

  85. Domhogan16 May 20, 2012 at 7:43 pm #

    well he’s clearly American.

  86. Domhogan16 May 20, 2012 at 7:43 pm #

    well he’s clearly American.

  87. fight4urpointofveiw May 20, 2012 at 8:44 pm #

    Haha yeah.

  88. fight4urpointofveiw May 20, 2012 at 8:44 pm #

    Haha yeah.

  89. DiamondNotch May 23, 2012 at 10:58 pm #

    Brilliant video. You deserve a some sort of prize :)

  90. DiamondNotch May 23, 2012 at 10:58 pm #

    Brilliant video. You deserve a some sort of prize :)

  91. malik007 June 3, 2012 at 11:07 am #

    thank you very much :D this video made my day :)

  92. electricmeatloaf June 16, 2012 at 2:44 am #

    Thanks so much for clarifying cooperative binding!! You make things so clear.

  93. divisorplot June 22, 2012 at 4:12 pm #

    Nice audio signature, appreciate the spoken word without the hyper noise noisy music.Information theory ,noise ect. Ture pure puer spoken word lecture.

  94. divisorplot June 22, 2012 at 4:12 pm #

    Nice audio signature, appreciate the spoken word without the hyper noise noisy music.Information theory ,noise ect. Ture pure puer spoken word lecture.

  95. andrewcunningham101 July 31, 2012 at 4:14 pm #

    really great video. thank you so much for taking the time to do this. you are a great teacher!!!

  96. Nim565 August 29, 2012 at 9:00 pm #

    I’ve been trying to understand this stupid dissociation curve for a year from a lot of different people but somehow i understood your explanation.
    Seriously you’ve helped me a lot!! :)

  97. Nespithe September 3, 2012 at 7:44 pm #

    Great video. Really helped me understand this concept.

  98. unhwildcat627 September 26, 2012 at 4:07 am #

    THIS SAVED MY GRADE!!!!!! Thank you so much Leslie!

  99. jonathan October 22, 2012 at 10:21 am #

    I go to a college in england, doing my A levels and this video really helped. thanks guys!!

  100. sarva khitana Bunbulama November 5, 2012 at 9:26 am #

    thank you. I was reading about partial pressure of gasses in blood and how that is related to H ions and bicarbonic ions but it was great to watch this now i know what they mean with conformational changes.

  101. chrissaygal November 10, 2012 at 9:11 am #

    would the release of oxygen from hemoglobon be consider a negative or positive feedback system?

  102. mrtigerucantfly December 13, 2012 at 9:57 am #

    Does it really matter how haemoglobin is spelt? I’m American and have always spelt certain words the British way….not sure why but to me the British spelling has always seemed correct. Like if my professor writes “liters” on the board, without hesitation I write “litres”, if he writes hemo- I write haemo- and so on….I know weird.

    Well anyway this video has been very helpful. Thank you very much! :-)

  103. Viren Chouhan December 23, 2012 at 3:39 pm #

    lol he sounds so happy!

  104. TheMinecraftingTom December 25, 2012 at 12:36 am #

    Doesn’t the 3rd conformational change make it harder for the 4th O2 do associate?

  105. gracecamp1 December 26, 2012 at 8:57 pm #

    I know I got confused too, think I worked it out:
    As the conformational change changes the shape of the haemoglobin it makes it easier for O2 to attach. However FIRST the O2 has to DIFFUSE into the red blood cell before it attaches.If you have 3 O2 already in there then it cant diffuse in as the concentration of O2 is too high in the RBC. However if it was near the lungs then the O2 could diffuse in as the concentration of O2 is lower in the RBC than the surrounding enviroment.RBC=RED BLOOD CELL

  106. gracecamp1 December 26, 2012 at 8:58 pm #

    Not sure if that’s right, but it’s the only thing I could think of!

  107. bunieshit January 1, 2013 at 2:54 pm #

    I don’t know what’s his problem, but I love your voice :D I love how easily I can understand every word you say, even if english isn’t my first language. If I have something I don’t understand, I come to your channel, because you are my favorite biology teacher online :] I can’t express how much you helped me, I have poor biology skills, but you actually made me understand it. I wish you were my teacher, not like it’s possible or something. :D

  108. MissRosy942 January 4, 2013 at 12:09 pm #

    This is great! im revising for alevel biology and i was struggling with this topic, this has cleared it was up! thanks!
    however did you spell haemoglobin right?? in England we spell it with an “a” before the e!!!

  109. Catherine Ruane January 4, 2013 at 8:07 pm #

    Thanks, hopefully this comes up in my exam tomorrow hehe

  110. Daniel Raza January 6, 2013 at 6:45 pm #

    love your accent!

  111. jcornwell4692 January 21, 2013 at 12:24 am #

    Thanks for help on my MCAT!

  112. Melissa Norris January 27, 2013 at 4:19 am #

    Just like everyone else, I have to say Thank You!! Extremely helpful and your enthusiasm towards this subject makes it much more enjoyable to watch! Blessings!

  113. ThaNosaN January 29, 2013 at 7:23 pm #

    Thanks a lot for this, after 1 year of studying physiology this is the only tutorial actually opening my eyes on what’s up with the curve! Your voice is so cool it would be insane if you wore dreadlocks as well hehe.
    Keep up with the great work! :)

  114. pellykate February 2, 2013 at 4:23 am #

    A-HA! Thank you!

  115. ReecieChan February 12, 2013 at 5:41 pm #

    Thank you very much for this video! I feel like I can understand anything in my biology lessons now!=)

  116. Flerick February 16, 2013 at 3:51 pm #

    Thank you!

  117. zombietokvid March 4, 2013 at 8:29 am #

    Straightforward and easy to understand!! Thank you :)

  118. dorothywx March 7, 2013 at 9:56 pm #

    Wowzers. This is super-duper-awesomely filled with awesomeness. Yesterday I thought to myself, I dont understand this, why is this so confusing, but after watching this today I can FINALLY say I understand oxygen dissociation curves. woot woot! Yesterday I even thought I could never understand this ever again, now today I am like wow its clear in my head, I can understand it!

    Anyways just want to thank you for your uber awesome efforts

    Byzers
    x
    o
    x
    o
    x :)

  119. zombietokvid March 9, 2013 at 7:40 pm #

    I agree~

  120. alexandanu March 17, 2013 at 5:49 pm #

    Thanks, this stuff actually makes sense now. it’s explained at a nice pace. Thanks

  121. LFCowen95 March 24, 2013 at 6:46 pm #

    You could’ve mentioned the change in the diffusion gradient when the haemoglobin molecule becomes more saturated. It’ll be harder for an oxygen molecule to bind with a haem group when it’s nearly completely saturated because it will be highly concentrated with oxygen so diffusion gradient changes. This explains the decrease in the gradient on the curve towards the end and explains why it’s difficult for 100% saturation. Still a fantastic video though

  122. Emily Walker April 14, 2013 at 3:22 pm #

    So good!

  123. raquelborn April 19, 2013 at 8:12 am #

    THANK YOU. Fantastic voice, nice speed, good use of language, no umming or ahhing. Don’t know what people are complaining about.

  124. Halfbloodwiz May 1, 2013 at 2:07 pm #

    OMG thank you so so so much!! Totally didn’t get this at all and now I finally get it!

  125. OOjuniperberry May 18, 2013 at 10:02 am #

    Your videos have helped me so much! Thank you :) xxx

  126. ibrahim2ibrahim May 20, 2013 at 3:25 pm #

    I hate American spelling… sheesh, imagine if I write that in my exam

  127. ibrahim2ibrahim May 20, 2013 at 3:37 pm #

    someone please enlighten me because i am very confused… if it becomes easier for other O2 molecules to join the Hb the more there are, how comes the graphs are sigmoid? shouldn’t they become steeper?

  128. notice0071 May 26, 2013 at 5:45 am #

    Tx

  129. cuoredipietra89 May 29, 2013 at 6:05 am #

    I’m sorry for english I’m an Italian student
    the curve is a sigmoidal curve because it is’ the result of an average between 2 other curves: the curve of high affinity (hyperbolic) that we get when hemoglobin binds O2 in the lungs….and the curve with low affinity (hyperbolic) that we get when hemoglobin leaves the ‘O2 in the tissues. by union of the two curves you obtain the sigmoid as you see in the video. XD

  130. cuoredipietra89 May 29, 2013 at 6:12 am #

    in effect the video is very simplistic and gives us a vision of elementary’ hemoglobin and its operation that in reality is far more complicated …. luckily XD

  131. gareth davies May 29, 2013 at 7:40 am #

    Sorry if I’m wrong, but is it not “haemoglobin”?
    Am i wrong? or does it change for different countries?

  132. boštjan kramar June 1, 2013 at 11:00 am #

    Thank you!!!!

  133. PalmeiroAna June 27, 2013 at 7:49 pm #

    Thank you, I love your videos!

  134. Kai Y June 29, 2013 at 12:12 pm #

    Thank you s to much. I’m a nursing student and I just could not wrap my head around this concept.

  135. Binayak October 1, 2013 at 6:28 am #

    This is a very interesting lecture with useful illustrations. Thanks for such a nice learning Website.
    Binayak

  136. Kayla Cassedy October 7, 2013 at 11:23 am #

    These videos are amazing! Please dont ever stop, you are helping my whole class learn this difficult subject!

  137. Angelo Classen November 8, 2013 at 11:17 am #

    you cant spell haemoglobin

  138. Samrina Ahmed January 30, 2014 at 12:36 am #

    Heloo Leslie

    I am realy feel excitement to read the comments of ur fans but Leslie in my computer all other videos are properly working except this web site(ww.interactive-biology.com).plz let me know the reason.Is any other softwere used here for working or same other.
    waiting ur reply
    Samrina ahmed