Cystic fibrosis pathophysiology

so the gene that's not working well in cystic fibrosis is called the C F T C R gene so my gosh it's long acronym and it stands for a thread that's quickly cystic fibrosis so they obviously named this after they ding to disease cystic fibrosis transmembrane which means it goes from one side of the membrane to the other conductance is letting things through across the membrane from one side to the other and then regulator so it controls the movement of something going across a membrane the two ions that are affected are chloride and sodium but keep in mind that cftc are is a chloride channel so chloride is physically being blocked by this channel networking and sodium is affected because as a relationship with chloride but sodium has its own channel which is not affected in cystic fibrosis the cftc our gene is all over the body and depending on where it is the situation is a little different but the common rule is the same and to illustrate this let's talk about this sweat gland this is a place where this gene has a big role and from this example it's kind of the same thing going across the body for cystic fibrosis symptoms so if this is our sweat gland it starts here so what is secreted into here it's a channel and then here is the surface to our skin I'm going to label this side skin so when sweat is first secreted by this gland there's a lot of sodium and chloride in it for sodium let's use blue notice that it has a plus charge sodium all over here at the same time there's also a lot of chloride in it chloride is a negative sign as you can see in nature positive and negative attract right so sodium the chloride like to balance each other out and their friends in other words the body likes the amount of sodium chloride to be about balanced so going along this sweat gland going towards the skin there's going to be channels to reabsorb this chloride and sodium into the body we don't want to secrete out so for sodium we have its own channels I'm going to use blue here they're just dotted along the way of course next to them there's the chloride channels now these channels are the ones that are affected by our CFTC our thing I'm going to label this so C F T C R in cystic fibrosis these channels are not working but let's look at this as a normal one so let's see is this normal sweat gland and normally as the chloride floats down here everything goes this way as it flows down here you'll leave through these channels and go back into the body so this space here is the body that's the skin that's the outside so these as they go along go back into the body and sodium does the same thing remember that we want to keep our amount of sodium chloride pretty balanced so as the chloride leaves so does the sodium through their channels and they kind of keep an eye on each other to make sure that their numbers are about balanced so when we get to the end here let's say that there's let's just say there are two sodium molecules left and they're buddies two chloride ions now sodium chloride this is table salt so this is why our sweat tastes slightly salty in our skin and this is normal because not all the sodium chloride will be reabsorbed just as an aside have you noticed that when you sweat a lot it gets to be a little saltier or the sweat has a stronger smell that's because this is going through this channel faster when you're sweating a lot and there's less time for these reabsorption so there's more salt left but that's still normal here let's look at a channel width in a person with cystic fibrosis so same channel structurally everything's going to be the same and here I'm going to label this one C F now initially the sweat the content of it being secreted into here is the same so I'm going to use the little dots instead of writing it out this time you already know blue is sodium and orange is chloride so same channels for the sodium and they're working just the same there's no problem with sodium channels however this time the cftc R Gean is not working so the chloride channels are all messed up so they look like this it's not open so so chloride floats down this way it can't leave you see it just has to stay in here and it keeps going towards the skin in sodium at this point this sees that the chloride is still in here the negative and positive want to stay together so even though the sodium channel is open the sodium doesn't go either because it's buddy chloride is still in here the body won't just take the positive sodium ions and leave the negative in here it has to be balanced so same thing the sodium gets trapped in here too pulled by the chloride so in this person when get to the skin it's almost the same content of sodium chloride as before as you can see this is a lot more than just two of each now I chose two as an arbitrary number which is to show you that this one is going to have a lot more and this is a lot saltier on the skin so one of the symptoms of having CF is having salty skin or even a baby with you a chloride test to see how much chloride is on the skin and they can point to CF but the pathophysiology of this channel is similar throughout the body I just chose one organ here to show you now really quickly in the lungs the problem is secreting chloride into the epic across the epithelium to moisten the lungs and since the chloride can't get secreted the sodium also doesn't get secreted in water follow sodium that's what the secretions are really thick because they're lacking in water that's how you get the thick secretions in the lungs and in the pancreas but here in the skin you get salty sweat