all right let's talk A Little Bit about the bicarbonate buffering system and so I 'm to try to make this as straight forward as Possible I like this particular illustration because there Are other WAYS that CO2 is moved in the Blood but the bicarbonate buffer system which is really What we're Looking at here is the majority of the WAYS that the way that CO2 is transported and so I think it's really effective to start with One idea and then Add the details On Top of it so This is meant to be kind of the introduction by no means ex expl of how this process works but I think it's really helpful to get kind of the Big picture idea here What your body is trying to do and we're going to Stay focused on this particular reaction that you see Right here we're going to look at it both at the tissues which is What's represented on the left hand Side and at the lungs and specifically the alveolus on the right hand Side and so if it's not obvious to you Why CO2 is produced by Cell metabolism you go and cite your textbook or find other videos talking about kind of the cellular mechanisms of the tca cycle or citric acid cycle as you see here but basically When we're using Oxygen to make ATP one of the Major byproduct here is CO2 and so Active cells which All Of The body All of our cells in our body are Pretty darn Active they're going to be kicking off a lot of CO2 especially when you increase your level of Activity or your metabolic rate in any way so these Active cells we're going to start with the tissues and we're going to work our way to the lungs the reactions are identical here Just Like Chemical reactions they're always going to be able to go both directions This is the same Chemical reaction but at the tissues it goes One Direction it kind of Flows with a High concentration of CO2 whereas at the lungs It's going to go The Other Direction It's going to go towards CO2 offloading so our cells are going to be producing lots of CO2 which is very soluble which is different than Oxygen CO2 is going to diffuse through the interstitial Space and make ITS way to the Blood vessels CO2 When mixed with water will actually form a weak acid called carbonic acid and that will happen on ITS own so if you take a Glass of water and you Just Blow Into it for for a while maybe like four five minutes you Just exhale All Of The Air that you exhale you put in there It will actually change the pH of the Water the Water will become more acidic now in our body We actually have an enzyme and called carbonic anhydrase and it does What all enzymes Do It speeds Up this Chemical reaction and so in the presence of a lot of CO2 and water carbonic and hydrates will very very rapidly convert CO2 and water Into carbonic acid Now then carbonic acid does What it always will do which a certain proportion of this carbonic acid that you produce will dissociation proton ler the pH This is fund mechanism ch pH Due to Cell metabolism a lot of times We Just Say that pH changes but This is the act maj mechanism behind that lactic acid is a lot of times What people think of When they think of Activity leading to a pH change Now lactic acid is Due to fermentation which Is actually not usually being used When going to be producing Mass CO2 and so This is lactic acid can change pH as Well but This is major mechanism and this is what links CO2 and changes in proton concentration in your Blood Once you get to this step what you actually done hydrogen Ion will actually GO off and bind to hogl which is what this Blue HB is representing That's What will happen to that proton but the BB is leftover and It's leftover negative and so if the Story ended Right here you would actually Start accumulating negative charges inside of the Cell and you would have a really really unbalanced electrical situation here so by Carbon It's going to move out of the Cell actually and in order to balance that change in negative charge you actually bring in chloride and this is called the chloride Shift and so chloride isn't really participating directly in this reaction What it's doing is basically balancing the charge because BB concentration are to get so high in the Cell It's going to move down concentration gradient if you lose too many negative charges you also have an electrical imbalance so You're going to have chloride moving back in Simply to to balance charges and if you notice a lot of times in Cell biology When You're Looking at these kind of reactions That's primarily What chloride does as an anion it basically Just balances charges probably before they even knew or tested that chloride actually did this they probably Just assumed that it did because they've seen it so many other places and so That's really What's going to be going on here When You're at an Active tissue You're going to be producing CO2 You're going to be changing your pH slightly and You're going to be kicking off bicarbonate Into the plasma and so This is the explanation when you read or have someone tell you that that BIC Carbon it is our Primary Place that we have CO2 in our Blood and so This is the Primary Carrier This is how CO2 is mostly transported in the Blood so as this Red Blood moves through your blood all the way back to yours lungs you have the situation over here and Again the Chemical reaction Is The Other Way around so pause the video right now Just take a look at the Chemical reaction It's the same thing you Just fli The arrows around and so What's important in context you guys We Just Went over the detail and so What's important in context is Just to notice that you are pushing CO2 Into this chemical reaction is breathing whole idea of breathing and Why you have to constantly breathe is in order to keep the concentration of CO2 very low in the alveoli if you do that then you will Pull in the bicarbonate Pull in the excess protons you Run this reaction backwards and produce CO2 in the Alve then bre out which keeps your body Stable basically you have a constant production of CO2 and if you don't do anything about it have too much CO2 and therefore too low of a pH in your body so the output is Right here but This output is Totally dependent upon your ability to breathe which drives down the CO2 level in your lungs because CO2 is very low in our atmosphere if we breathe We Keep this level very very low the partial pressure of CO2 Remains low and everything is happy you have this cycle of CO2 being produced and CO2 being kicked if you change your ventilation rate or you Just Don't bre Enough or Sometimes if you breathe too much You can cause pH imbalances and It's because if you hyper ventilate right now do it while You're sitting down if You're going to do it You will actually Drive the CO2 too low Pull in too many protons and actually make yourself slightly Basic and the neurons in your Brain will s first get A Little Bit of spotty Vision but Just try to Look at this in Grand sche stepping back Looking at this whole process of CO2 production CO2 EF Flux or getting rid of that CO2 that you've produced and you do this through this main Chemical reaction here the whole thing is this bicarbonate buffering equation that you can see illustrated a billion different WAYS but I think This is a Pretty good introduction to the main idea behind this