 The final medical example I'm going to show you is just as severe if not worse. Not so many decades ago premature infants that were born roughly before week 26 or 30 or so would die simply because they couldn't breathe. The reason for that is that the babies do not yet express some protein, some genes that are required for breathing because again the body does not expect to have to breathe until week 40 when you're born. It took quite a while before researchers understood exactly why this happened but it has to do with the structure in our lungs, in particular the alveoli responsible for the very end of the cells where we had the air exchanging air molecules with the hemoglobin on the inside. This alveoli will have to undergo some structural changes where we breathe in, they have to expand and contain more air and when I when I exhale they're going to need to collapse a bit right and contain a much smaller surface and that's mean that the membrane around them will have to expand and compress all the time. That takes a lot of energy and nature has optimized this in ways I will show you in the next slide so avoid this taking too much energy by expressing some proteins helping but these are not expressed if you're 25 weeks old fetus. It's not entirely easy to treat that but we would like to create some sort of artificial protein or something that had properties similar to this. I'm going to need to show you what this pulmonary surfactant is and how it works. So in your lungs there are two phases when we compress the membrane that means that you're going to end up with extra membrane and what this surfactant appears to do that is binding one membrane layer to the next membrane later almost like folding up laundry or something so this takes care of the excess membrane but in a very nice and tidy way. Then when we breathe in that I expand the lungs then I'm going to need that extra layers of lipids the laundry and then they rapidly let go of each other again so that keep things in order but make sure that there is always spare membrane available and occasionally that's even in some separate vesicles or so. This works when we're adults because a few weeks before we're born it works when you're when it works from your born because a few weeks before you're born we start expressing these proteins that are required for respiration and that is occasionally why you hit the baby on the bottom to get make sure that it takes its first breath. Taking that first breath is the first expansion that might require a bit of extra force. What we would need to cure this is that we would need a protein that has exactly the surfactant properties and acts in roughly this way and then we could just give that to the baby and in that case the babies would survive. You know what that is not science fiction you do that with premature babies now and you've done it for probably two decades and that's why it's routine babies will survive for week 24 or so. Here's an example of a chest x-ray roughly 30 minutes after administering the pulmonary surfactant and then a couple of hours after administering it. Part of this might be exposure but in particular you can see that there is now air in the lungs of the infant that is likely going to be healthy and lip because again now the baby is born and a few weeks later I bet it's going to express its own pulmonary surfactant. It's a very temporary measure but without this measure they die because they could not breathe on their own. There are a whole lot of people alive today that can that have their lives to thank for pulmonary surfactant.