welcome to learn a love apology for free with mr. ik in this video I'll be going through gas exchange in terrestrial insects so we're looking at the anatomy adaptations and how they vent water loss so first of all just a bit of an overview on the terrestrial insects so they all have this exoskeleton which is made up of chitin which is a hard fibrous material to help protect them but also it contains a lipid layer to prevent water loss they don't have lungs for their ventilation and gas exchange system instead they have a tracheal system and that's all be going through so limiting water loss this is one of the big things for any organism that lives on land which is what we mean by terrestrial they have to balance being able to exchange gases with reducing the amount of water loss and in particular a 2 I focused on insects and plants so what we'll be looking at is what are the adaptations insects have to reduce water loss so there's three key things first of all their gas exchange system has quite a small surface area to volume ratio where water can evaporate from so having that small surface which is linked the side of spiracles there's only a very very small hole where water can evaporate from we also mentioned they have that lipid layer on their exoskeleton and that makes them waterproof so water can't evaporate across all of their body and it's just through the spiracles and the spiracles which we're going to look at in a bit more detail this is tiny holes on their abdomen where gases can enter and exits but also water can evaporate from but number one list of the very small but also they can open and close so they won't remain open permanently so they can be closed and this is to prevent water loss so we ever look then at the trick your system so involves trachea tracheas and spiracles as the three structures within this tracheal system so first of all the spiracles are round their valve like opening I mean and they can open and shuts and they run along the length of admin so here on this insect all of these tiny holes we've got one here here here here here and here that's another one to stab those are the spiracles so they're just tiny tiny circles right on the outside which we can see down here as well which then lead into the tracheal tube system so those spiracles that can open and close to control water loss and oxygen will be diffusing in calmed outside diffusing pants and the spiracles attached to the trachea so takea are a network of internal tubes within the insects to keep those tubes open a bit like the trachea in animals they have rings within the trachea to strengthen them to keep them open and to stop it from collapsing so gases can constantly move in and out the final structure is the trachea so the trachea branch into even smaller tubules and that's what their trails are and the trachea will then reach to every single tissue within the insect to deliver oxygen at the respiring cells so that's how all the cells within the insect will receive oxygen and we'll pick up the carbon dioxide from aspiration to then diffuse out so those are the key structures the final parts are just looking at how then gases can move in and around the tracheal system so the first method out of the three is just simple diffusion so when the cells respire within the insects body they're using up oxygen and they're producing carbon dioxide and that creates a concentration gradient between the concentrations of those two gases inside of the insect compared to the outside atmosphere and because of that concentration gradient and because the insects are so small and this distance between the trachea and outside is missing that then means a simple diffusion can occur number two is gas exchange in mass transport so this is where the muscles within insects abdomen can contract and relax and in doing this it's a way to pump and move gases on mass in and out of the insects tracheal system so that's just going to speed up and increase the volume of gases the final method is quite different and this is fluid pressure changes so when the insects are flying the muscle cells will be respired respiring aerobically to begin with but very quickly it will turn to anaerobic respiration as they run out of oxygen and that will then produce lactate or lactic acid because those cells are producing lots of lactate that lowers the water potential of the cells and that causes water to move from Shaquille's those tiny tiny tubules into the cells bars Moses now because liquid that naturally occurs in the Shaquille's is moving out into the cells it then provides a lower pressure in the trick eels compared to the atmosphere and if you've got a lower pressure sorry a lower volume you will also have a lower pressure compared to the atmosphere and that is then what then forces in more air from the atmosphere this drop in volume of gas and drop and pressure causing the air from the atmosphere to draw into the tracheal system so just in summary for any gas exchange and system that you learn you're always looking for what provides the large surface area and in this case it's a large number of these fine trick eels as well as it's lots of sphericals running along the abdomen sure diffusion distance or pathway and in this case the walls are the trick eels are very thin but all say the distance between the abdomen and the outside of the insect so the difference between the distance and the spiracles and the tracheal is very very short it's the gases they have far to defuse and finally is how is that concentration gradient maintained and in this case it's because those respiring cells will be using up oxygen and producing carbon dioxide that is maintaining this steep diffusion gradient so that is this four gets exchanged in insects if you found a helpful please give it a thumbs up and click subscribe to keep up to date [Music]