Types of Circulatory Systems – Cardiovascular Heart Health

Types of Circulatory Systems - Cardiovascular - Biology - NEET 2021 - GCSE

Types of Circulatory Systems – Cardiovascular – Biology – NEET 2021 – GCSE
The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and pH, and maintain homeostasis.

The circulatory system includes the lymphatic system, which circulates lymph. The passage of lymph takes much longer than that of blood. Blood is a fluid consisting of plasma, red blood cells, white blood cells, and platelets that is circulated by the heart through the vertebrate vascular system, carrying oxygen and nutrients to and waste materials away from all body tissues. Lymph is essentially recycled excess blood plasma after it has been filtered from the interstitial fluid (between cells) and returned to the lymphatic system. The cardiovascular (from Latin words meaning “heart” and “vessel”) system comprises the blood, heart, and blood vessels. The lymph, lymph nodes, and lymph vessels form the lymphatic system, which returns filtered blood plasma from the interstitial fluid (between cells) as lymph.

The circulatory system of the blood has two components, a systemic circulation and a pulmonary circulation. While humans and other vertebrates have a closed cardiovascular system (which means that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open cardiovascular system. The lymphatic system, in contrast, is an open system providing an accessory route for excess interstitial fluid to be returned to the blood. The more primitive, diploblastic animal phyla lack circulatory systems.

Many diseases affect the circulatory system. This includes cardiovascular disease, affecting the cardiovascular system, and lymphatic disease affecting the lymphatic system. Cardiologists are medical professionals which specialise in the heart, and cardiothoracic surgeons specialise in operating on the heart and its surrounding areas. Vascular surgeons focus on other parts of the circulatory system.

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In the previous lecture we discussed about that why larger organisms with a higher metabolic rate need circulatory system what we discussed in the previous lecture we discussed mainly that unicellular organism or organism with very few cells do not need a special circulatory system but i explained it explained it very well that as organisms become larger as organisms become larger and their metabolic rate increases right then what happens that’s in so many cells to provide the nutrients and remove the waste products we need special fluid which can be circulating and transporting the substances within the organism from one place to the other place right now in today’s lecture we are going to talk about types of circulatory system previously we discussed why we need circulatory system and in this lecture we are starting with the topic of what are the different types of circulatory system and we will start with the simplest circulatory system and see that how circulatory system during the evolution right it grows and gets more complex and more efficient right for example we’ll start first of all with the open circulatory system right which is the simplest form of circulating system and it’s present in the insects right for example in insects then we’ll talk about closed circulatory system right an example of closed circulatory system the simplest closed circulatory system is single closed circulatory system we will discuss about circulating system of fish after that we will discuss the differences between open and closed circulatory system right again i will repeat first we are going to talk about the simplest circulatory system that is open circulatory system will discuss in detail don’t worry you will know each and everything right classically we can give an example that this circulatory system is present in insects right then we will talk about in the next part of the lecture that what are the closed circulatory system right and in the closed circular system and second part of the lecture we will discuss that single closed circulatory system which is present in fish right after that i will mainly focus on what are the real differences between open and closed circulatory system once we have mastered these things then we will go to that thing how in the frogs single circulating system is converted into double circulatory system right now so once we have developed the double circulatory system into frog is that right while circulating system from single is converting into double system initially it is partially developed so we call it double closed circulatory system which is incomplete or we simply call it incomplete double circulatory system incomplete double circulatory system after that when we go to more advanced animals like okay talk about beautiful human beings right some of them are sitting here others are hearing me hopefully so watching me in them there is fully developed complete double circulatory system is that right and closed so let’s come over here what is what is what we are going to talk about first of all in the previous lecture i just want to basically tell you what we are supposed to learn in this series of lectures previously we talked about why multi-cellular organisms with relatively higher metabolism need circulatory systems right then today’s story will start different types of circulatory system first of all we’ll talk about simplest circulatory system which is open circulatory system right classically present in fish insects it means you are listening yes classically presenting insects open circulatory system after that we’ll talk about we’ll talk about closed circulatory system right we can say that circulatory system can be divided into yes circulatory system can be divided into open circulatory system and closed circulatory system right and closed circulatory system can be yes single circulatory system which we’ll discuss later and single closed circulatory system and double closed circulatory system and double closed circulatory system is yes incomplete incomplete and complete right now classical example in case of open circulatory system is yes insects right insects then in closed circulatory system right single closed circulatory system is yes what is this fish there are other examples too but we are going to discuss typically about fish then double closed circulatory system from single closed we shift to the double close and when we go to the double close there is incomplete double close and fully developed or complete double clues incomplete classical example is frog and complete is like mammals other members like human beings right now let’s start with what is the open circulatory system in an insect right what is open circulatory system in an insect again i will repeat circulating system consists of a yes consists of some fluid which needs to be circulated within the body of the organism to transport nutrients and transport different metabolic waste products right now let’s come back let’s draw a beautiful insect which is very happy because we are going to study that insect right where it’s going to be now yes this insect why it is happy because it is center of attention right right okay here it’s not it’s just a schematic diagram of a happy insect which we are going to study you can see it it’s like that right these are the okay wings now how the circulatory system works inside that how this open circulating system works inside that how the simplest one of the simplest form of circulatory system to understand the circulatory system you just remember one thing there’s a fountain within the insects there’s a fountain now what i mean by fountain have you seen water fountains right if i draw a water fountain what it should be doing let’s suppose this is water fountain it should be taking up the yes fluid blood pumping it upward and then throwing it out and then this water come down and again it is going in so we’ll go of course into detail but simplest way insect arthropods their circulatory system is just a very little fountain present within their body cavity the headset very little fountain right now why we call it open circulatory system because part of the fluid will circulate through a tube and part of it is moving through the cavities of through the open cavities let’s start into detail first of all in the middle mid section in the middle of the insect there’s a tube i’m not an insect but for a while you just imagine right on the insect now this side is my dorsal side this side is my ventral side here i want to tell that dorsal side mean any side in an animal which is up upper and back part back part this is dorsal and ventral is front part or belly part and under part right in the same way insect this insect i’m showing like that so you are looking like this but if you look at the insect like this insect like this then this will be the dorsal part this is the back of the insect and this is the belly of the insect so this is the dorsal part is that right but when we draw this insect if we draw it like this so this is the dorsal side but if i make a diagram like that then i will make it in the center is it right so this tube this tube i am going to draw it here right so what is there in the dorsal part of the insect near the back in the midline in the middle in the middle is that right there is a tube there’s a vessel we call it dorsal vessel what should be the name of this vessel dorsal vessel right so insects have a dorsal vessel now this vessel is just like a mountain i will draw it okay now don’t imagine other things it’s just dorsal vessel right now this dorsal vessel if i show it on the side it will be like this is it right but if we are looking like in this form it’s going from down down side or back side of it and it’s going to the or we can say from its tail end of course insects don’t have tail but just tail end or back end to the head end right now what is happening this tube which is called dorsal tube or dorsal vessel so i will write down the term here dorsal vessel now this dorsal vessel has one part which is towards the back end of the insect and other part which is towards the head of the insect is that right now with this bad part okay i’ll make it a little more this back part is able to contract expand and contract right it will expand and then contract expand and then contract so you can say it is working like a pump this part is working like a pump because it is able to generate the pressure it can squeeze the fluid which is present within it can squeeze the fluid which is present within is that right now when it will squeeze the fluid fluid will move to the head is that right so what is happening that it is pushing the fluid upward to the head side and because this part of the dorsal vessel is able to compress the fluid which is present over here i will tell you the name of this fluid later you just trust me there is something some fluid here right so it is compressing and squeezing or milking have you milked the i mean cow or you have never milked cow or buffalo no very sad have you ever milked the cows or buffalos only cows not uh ox or anything else yes good so if you know what is milking so what is happening that this part of the tube it will have squeezing movements and pressurize the fluid which is present within the tube this fluid will move towards the head this will move towards head and this part of the tube which is actually it is extending up to the hydrogen right i should make it a little correction you know insect is so happy getting so much attention it’s just like i think it must be a female insect now once fluid reaches circulating fluid reaches to to the that end of the dorsal tube or dorsal vessel which is to the head side right fluid will eject from it it will come out of it it will eject out of it the word is ejection right not any other word so fluid will eject and it will start yes it will set free now previously fluid was present within the tube and now it is ejected released in the body cavity of the insect where there are other organs also now this fluid which is released from here from the head end gradually it will percolate yes downward yes it will move in body cavity and it will keep on moving down and as it is moving down what it will do right it will basically there are special type of openings here right and these openings are called ostia what is this called one one opening is ostium and these openings are called together as a group ostia so what happens that this fluid which has been ejected or released near the head region or within the hydrogen into the body cavity of the insect this fluid will percolate down move the move down or move backward right and from the head end of the insect right it will start moving down and when it is moving down then what happens from these osteo it will re-enter from these ostia this will re-enter into dorsal tube right which region this area which is able to pump we can say it it’s really not a true heart but we can say it this part of the dorsal vessel is basically heart of the insect for me it was very surprising that even insects have heart right i don’t know who’s maybe female insects also steal their hearts or i don’t know what happened there but there is some hard business there too so again there’s a dorsal vessel right which was present on the back end of it not to near the belly end rather on the back of this and most posterior part posterior part i mean towards the tail end this is contractile it’s able to milk the fluid and push the fluid forward towards the head end is that right this component can we can say it is behaving like a heart it is behaving like a pump actually it is a sort of very rudimentary primitive pump right so what will happen with these are multiple chambers right in between the two chambers there’s a little opening this opening is called osteum and because there are multiple openings as a group we can say they are ostia and because this ostia allow the fluid to enter is that right allow the fluid to enter into heart of the insect we can say what kind of ost are these they are they are taking the current of the fluid inside they are taking the fluid inside so we call it in current in current ostia so we can say now that basically circulatory system of the insect consists of mainly a dorsal vessel the back end of the dorsal vessel has contractile elements and in current austria now there are special valves at this ostia let me draw one ostia osterium now let’s suppose i am saying that there is ostium here opening here these are vertical slits this is also a vertical opening or slit this word is slight slit not right slit so these are vertical slits or ostium ah fluid is supposed to move in is that right move supposed to move n now when fluid will move in answer is after squeezing the fluid this chamber relax of course they will contract and then relax after contraction when they compress they push the fluid forward to the head but when they relax pressure inside drop pressure inside drop when they are relaxing pressure inside drop and these slit valves open and they will suck the fluid in you understand it they will suck the fluid in but once fluid is in then they will squeeze it sucking and squeezing sucking and squeezing so this sucking and then squeeze now once they will squeeze when they will squeeze what will happen now you might think that it will reverse outward no it will not reverse outward the reason being now listen carefully here there are there is a special valve mechanism there is a special valve mechanism and this is the valve inside right again these are also valves inside now what happened once the contract let’s suppose this squeeze and this also squeeze the fluid which is already in that will push the flaps flaps of the valves and valves will close they will close so what we have what i’m saying that when this is going to first of all let me repeat this is which part this is the posterior most or backward most part of the dorsal vessel right this has slight dilations which are able to contract and relax and these are called heart component of the insect is that right now special thing is that in between these chambers there are special openings which are called ostia right now these ostia have special valves okay i will make the valves color different let me make it the valves which are inside they are like this now what happens this is a valve and this is a valve when they will squeeze the pressure inside will go up but they are designed like this that when pressure goes up fluid will push the leaflets push the leaflets and close these valves it means that they but when these chambers will relax pressure will drop and valves will open so it means these are one-way valves when tube is contracting and start squeezing the fluid the valves will close right and when it will relax pressure inside will drop and valve will open if it is relaxing the valves will open the valves open so this is when it is relaxing but as soon as start pressurizing before the fluid eject out it will push these valves together and they will close is that right so we can say that due to this special openings only back part of this dorsal tube which is acting as heart can pull the fluid from the body cavity in can pull the fluid in through the ostia but once it start contracting fluid will not go out through these openings because valves will close so when it contract the only option for the fluid is move forward is that right now once it again i will repeat so it is just like a fountain that at the bottom of the fountain it is able to take the fluid and then within the fountain base this is the base of this like a fountain it is able to take the water in then there is a pumping mechanism which will throw the water upward through a tube and then tube at the top must be open and from here this fluid will go into open cavity so this is a and because this fluid when it will come down again it will be taken in and again it will be squeezed this is the fundamental basic model of open circulation the question is that why we call this open circulation answer is very simple we call it open circulation because fluid all the time the circulating fluid all the time is not present in tubes here it comes out of the tube into open spaces in the body cavity closed circulatory systems are those circulatory system where circulating circulating fluid is always remaining within the special tubes like our circulatory system right our circulatory system how is it that in our circulatory system fluid is present in heart fluid is of course blood then from the heart blood is carried to the arteries then into capillaries then into veins and then back to the heart this is the basic model now i will just for comparison purpose let me show you the difference between a basic difference between open and close circulation there are many many differences which i will talk later but basic differences let’s suppose this is a circulatory system suppose yes i can say that that here is hard and these are the different vessels these are the vessels and even circulating fluid if it always remains within the vessels mainly it is always remaining within the vessels and this fluid is not coming out as such right let’s suppose these are the cells right these are the cells we should get nutrients from the blood and this is example of closed circulation then i will show you how it differs from open now in for example in human beings hard and very simple form of circulation later on we’ll discuss in detail that human beings have double circulatory system but for a while you just imagine there’s a heart and circulatory fluid is blood and blood is moving within the different vessels now if it is having a molecule of nutrition here let’s suppose this is nutrient right this nutrient is not exchanged between the blood and the cell directly rather there is another type of t fluid which is around the cell and this fluid is called tissue fluid right this is tissue fluid which is present around the cells is that right to be more technical this fluid which is out of the vascular system but in between the cells this is called interstitial fluid what is it called interstitial fluid so actually if this nutrient molecule let’s suppose glucose molecule if this is a glucose molecule it has to reach to the cell first from the blood this should go to the interstitial fluid then from the interstitial fluid it will be taken up by the cell it means that in closed circulatory system substances which are present within the circulating fluid they do not directly exchange with the cells from the blood from the circulatory fluid first they have to shift to the interstitial fluid and from there they can be exchanged with the cells in the same way if this cell is supposed to produce a waste product it will not throw the waste product directly into blood this cell will throw it into interstitial fluid and from there it will diffuse into blood you are getting it so this type of circulatory system where the circulating fluid with all transport substances even though it’s circulating in the body but it stays within the special type of tubes called arteries capillaries and veins and within the heart right this is called closed circulatory system what is it called closed circulation system and in closed circulatory system the substances don’t directly exchange between the circulating fluid and the cells substances are exchanged via the through the interstitial fluid but look here here the circulating fluid even though initially it is present in a tube but eventually it released into body cavity now in the body cavity there are many tissues suspended right here i want to tell that body cavity here by different type of septa i will not go into detail now when i will teach you in detail cockroach anatomy then i will mention the different type of partitions or divines we call them septa with this body cavity has some sceptical deviance and input and these space between the septa let’s suppose this space and the space right these species are called sinuses what are they called sinuses now listen actually this circulating fluid i have not told you the name of the circulating fluid i’m holding it this circulating fluid will come out from the head region of dorsal vessel and now it is op now it is no more in a tube now it is no more in a tube it has ejected into body in the body cavity and body cavity is having multiple septa which divide the body cavity into interconnecting spaces which are called sinuses body cavity is having deviance called septa we’ll discuss that into detail later and these septa divide the body cavity of the insect into intercon connecting spacing with spaces which are called sinuses so what happens this fluid will percolate through it will wash through freely splashing around you are understanding if the insects start dancing the fluid is also jumping around within the body splashing it is free it is not in a specific vascular tube so this free tube free circulatory fluid will move through the yes sinuses right and if there are cells which are waiting for nutrients let’s suppose here’s the okay there’s a cell here right there’s the cell here this is i’m just showing one or two cells but actually there are millions of cells which are making different organ of this insect or this cockroach now what will happen this fluid will directly bathe the cells this fluid will directly go to the cell and give them the nutrients and take away the metabolic waste no no special interstitial fluid in between so if there was molecule of glucose here which was pumped through it it will come into open space this glucose molecule in the body cavity and when fluid is passing actually i can say the fluid is washing over the different cells and tissues while it is washing it is providing them the nutrients directly without it and taking up the metabolic waste directly and because now once it is ejected from here it is no more in a special tube no more in a vascular tube it is percolating and moving freely in a body cavity so we call this system is open system but even in the open system fluid will gradually return back to the pumping mechanism and again it will be what it will do fluid will go from here of course it will go to gastrointestinal system elementary systems insect take up the nutrients or right from the provide the cells nutrients give the waste product to the excretory organs and eventually return back to the dorsal tube back part of the dorsal tube right and from here that will again enter into it and then again it will be pumped right and it will again release this part can be called heart of insect if this is called heart then this part which is no not having pumping gravity activity it is not having pumping activity it is just acting as a pipe this can be called aorta very little leota rudimentary primitive iota right so now you understand why this system is called open system and why that is called closed system so primarily the circulatory system in organisms is divided into open system and closed system open system is classically present in insects and closed system is present in fish in simplest form then closed system becomes more advanced for example will study in frog then closed system become very advanced for example human beings is that right mammals now come back question is what is the name of this fluid in human being the circulating fluid which is present into closed system we call this fluid blood and human being we call this blood and what is this fluid interstitial fluid what is it called interstitial fluid and i want to mention one more thing some when nutrients come out some fluid component and proteins from the blood also come out blood as such total blood as a whole component does not come out but some nutrients come out of the blood into interstitial fluid uh through the capillaries which are very thin vessels through that a little fluid with proteins also come out into interstitial fluid that fluid which is added to the intestinal fluid from the vascular system that can be drained by special pipes right and brought it back to the circulatory system this fluid and this fluid is called lymph what is it called lymph so what is lymph lymph is the fluid which is present in lymphatic vessels but what are lymphatic vessels lymphatic vessels of course are having lymph so we couldn’t make a proper concept we should say that vascular from the vascular system of the closed closed circulatory system right substances are exchanged between the interstitial fluid and blood and then between the interstitial interstitial fluid and tissue cells exchanges occur but whatever extra fluid which comes over in the interstitial area or extra substances which cannot go back to the blood they are drained by an accessory pathway they are drained by an additional pathway right this pathway is called lymphatic system and fluid in it called lymph so in close circulatory system like humans classically we have circulating fluid called blood which is present within the closed system then outside the vascular system and in between the cell there is interstitial fluid and then there is lymph so we can say here what kind of fluids are there there are three types of fluid in closed system circulating fluid like blood which is present within the vascular heart and tubes then second was interstitial interstitial fluid which was present in between the cells we also call it tissue fluid and then another draining system some of the protein rich fluid is draining right this is called lymph so when we talk about closed circulated system like humans we have three components we have blood we have what is this enter special fluid and we have length now let’s compare comparison is very very uh i must say it should not be done let’s compare a human being with an insect circulation system now insect this fluid is present for some part within the tube from here up to here so it is behaving like blood it is behaving like blood it is not true blood but when it comes out it becomes something like interstitial fluid and something like lymph so it means this fluid which is moving around right this fluid it is working as blood are also working as interstitial fluid and also working as lymph right so it means that in open circulation clearly we cannot demarcate between the blood interstitial fluid and the lymph right so but here what is happening in more advanced system blood interstitial fluid and lymph can be distinctly differentiated is that right so because this fluid cannot be differentiated where it is blood and or we can say this functionally this this fluid circulating fluid in the insect is behaving like blood also blood anything which is blood can be called him him i don’t know what is the right spelling h-e-m or h-a-e-m just confirm it right my spellings are usually not that good as now listen this what is this study of the blood and its component is called hematology this is heme right now this fluid here is behaving like him then it is behaving like interstitial fluid then it will behaving like lymph also so this fluid is given a very special name that is called hemolymph what we call it hemolymph so what is this green fluid in the insect hemo lymph hemolymph so these spelling the right haem him or we h e m o also is okay now hemolymph so what we’ll say now that basically the circulating fluid in the insect is not blood that is hemolymph why we call it hemolymph because sometimes it is behaving like heme like blood and sometimes it is behaving like lymph and body fluids right so this is hemolymph so if i’m no i’m not insect if you are insect what kind of circulating fluid you have hemolymph and if you are human then what kind of circulating fluid you have blood with that in between the cells you have interstitial fluid and another draining system for the lymph fluid am i clear so what is this say loudly what kind of fluid is this hemolymph right then this hemolymph even though passes is present within the dorsal vessel and it is pumped by the back end of the dorsal vessel and it is ejected on the head end into free body cavity there is a special name of this body cavity also it is open here but there is a special name of this body cavity the special name of this body cavity is yes this cavity in which this is freely percolating splashing washing the cells providing the nutrients removing the metabolic waste moving the hormones about here and there right this uh this body cavity through which this fluid move that is called hemo coal hemo coal uh some people call it hemocyl both terms are used and both are right here you know in life they’re very less situation where you have options this is one of that situation you have options you can call it hemocol you can call it hemo seen i would love to call it hemocol right so in our lecture we will continue saying it hemo coal but whenever i talk about hemo coal you understand i’m talking about hemo seal they are one and the same thing and what is hemocholohemosil in an insect hemo coal or hemocyle in an insect is basically body cavity of the insect in which hemolymph freely moves and circulate right now this hemochole h a e m hemo coal hemolymph hemochole now now we can explain it in another way insect circulate another oh very important thing which i remember suddenly yes you see our blood is red color right you can say insects are not having blood not having true blood or we can say insects are not bloody right they are just having hemochol now a hemolymph circulating through the hemo coal hemocoil is the cavity divided by the septa into interconnecting sinuses in which hemolymph is moving and coming in direct contact with the cells and doing the exchanges is that clear any question up to this now a very important thing our blood is red but this hemolymph is not red why it is not red it is somewhat greenish or someone depending upon the insect that what kind of insect you are it depends on what kind of hemo lymph color will be there but basically it is not red why our blood blood is red because our blood is having hemoglobin our blood has red blood cells right and red blood cells are having a special molecule which is called hemoglobin this is oxygen carrying capacity oxygen carrying pigment or oxygen transporting molecule hemoglobin now their fluid is not having red blood cells and of course not having hemoglobin it means it is not red and of course it is not red so this is another difference that in close circulatory system hemoglobin is present and red blood cells are present but in open circulatory system red bloods are not present hemoglobin is not present or hemoglobin which can transport the gases we call it respiratory pigments respiratory pigments are not present the question is that then how the seldom insect get oxygen and release carbon dioxide the answer to that is listen carefully answer to that is that this hemolymph passing through what is this hemo coal is a very slow system it is very slow system but this pumping system which is closed system we’ll discuss later it is very rapid system is that right now this system hemolymph circulating through the hemocore going back to the dorsal vessel and again pump back into hemochol or body cavity this whole system open circulatory system the fluid moves very slowly fluid move very slowly and we don’t need much energy to move it right we don’t need not we insects don’t need much energy to keep keep or maintaining this circulatory system functional it’s a low energy demanding system slow movement of the circulation of the fluid slow circulation of the hemo lymph right problem is that cells require oxygen very rapidly they cannot wait that fluid will do a catwalk and come slowly and maybe it will it is stuck in some sinus and maybe it moves forward or backward or if insect become like this fluid also become like this cells want oxygen immediately cells need removal of carbon dioxide immediately that is why here nature does not depend on the circulatory fluid for transport of gases insects have special mechanism an independent mechanism of air supply we’ll discuss that later but that mechanism is called tracheal system what is that called tracheal system tracheal system which is present in insects this is a network of very elaborate network of tubings through which air is moving and bringing oxygen rapidly and removing the carbon dioxide rapidly that is why hemolymph does not need hemoglobin so it means hemolymph which is circulating fluid it is not rapid enough to transport the gases that is why insects for gas transport are having tracheal system is that right but in humans from respiratory system from the lungs gases oxygen is transferred into blood and blood is circulated very rapidly in human system and rapidly transported to the tissues health oxygen is supplied and removes the carbon dioxide but as compared to that if you talk about insects their circulatory system is very slow advantage of slow circulation circulatory system is that less energy is spent to maintain the circulatory pattern the disadvantage is that it can there are many disadvantages one disadvantage is that it cannot it with this slow movement the system is not rapid enough to transport gases so insects for transport of gases is the independent system called tracheal system and their circulatory fluid or hemolymph does not transport gases significantly that mainly transport different nutrients mainly transport hormones within that insect and transport here and there and remove the waste product is that right am i clear this is one advantage that it is low energy is required to maintain the circulatory system but here i mentioned one disadvantage what was that disadvantage yes what was that disadvantage that it is so slow that it cannot be dependent for transport of oxygen and carbon dioxide for that we need special type of then another thing if the system is so slow can this slow layerly moving fluid transporting mechanism can it maintain the metabolism of very big organism no look if you compare one insect with the one elephant or camel do you think camel or elephant can depend on such kind of circulatory system no they have closed and very efficient and very rapid flowing fluid blood is that right but in fact i have this issue that this kind of open circulatory system can occur is suitable only for smaller organisms like insects do you find a big insect like a donkey have you seen that not yet okay good no i think you are not going to see that right but here it reminds me one thing there were times in evolution about 200 million years back there were very big insights [Music] very very big insects right but the problem was that they were having circulated system which was very very slow so those insects were also very slow but then some animals developed more rapid and advanced circulatory system like birds birds have a closed system and four chambered heart then bird evolved and birds were very happy to prey upon and eat such insects and such insects so big even unable to compete with the birds for the nutrients eat apples that is why over the evolution only smaller insects are left why because bigger could not compete is that right but we have so many birds around right one of my students his name was birdie i never knew why but anyway come back so we were talking about disadvantages of this system disadvantage of this system is because it is slow it can cannot carry the oxygen and carbon dioxide because it is slow it cannot effectively take the nutrients to very distantly distant organs like human if if human have open system do you think they will survive they will not because the slower system will take maybe five months to reach to your foot to take the nutrients is that right so for little insect with relatively low metabolic rate the system works okay again open circulatory system why we call it open circulatory system because part of the circulatory root is open in the cavity it is no more in a specific tube that is white open circulatory system we can say this is half loop complete loop is not by the tube any question up to this okay let’s come back let’s review it very rapidly insect circulatory system we can say if i happen to be insect i hope not so but you never know even maybe they are happier than us we don’t know i’m sure insects don’t need to give the lectures they don’t need to attend the lectures or memorize these things but anyway let’s come back if i happen to to be an insect first of all on my dorsal side there should be a vessel what is this name of this vessel dorsal vessel now back end of this dorsal vessel is contractile so it is called pump and front end of this which is towards the head is not contractile it acts as a simple tube which is called iota dorsal aorta is that right now this pump this contracting chambers in between the chambers there are special openings which are called austria right when this is squeezing the fluid the what is this valve of the ostia and some sexy people call it lips of the austria right valves of the austria or lips of the austria close when it is contracting and fluid is ejected towards the head but whenever they relax ostia lips move away and let the fluid in so what is happening that in the insect there’s a dorsal vessel and backhanders of the dorsal vessel act as pumping mechanism and within the segments of the pumping mechanism there are openings called ostia ostia are having in current direction of the fluid guarded by the valves not lips right or okay you want to call lips or lipstick it’s up to you so ostia are having lips right distract me lips okay uh call it valves while they’re designed like this that whenever they are squeezing valves will close and fluid will only move upward forward or headward and whenever they relax they are able to suck the fluid in so again basic pumping mechanism back end of the dorsal tube right when it relaxes it sucks the fluid in and when it squeezes it pushes the fluid headword towards the head right what is the name of this fluid hemo lymph why we call it hemolymph because it is working like heme blood and also working like lift and also working like interstitial fluid so we call it hemo lymph and closed circulatory system as i told you here blood interstitial fluid and lymph are distinct fluids they can be differentiated from each other but here in hemolymph we cannot say that it is really blood or it’s really lymph or it’s really interstitial fluid actually actually really speaking it’s all of them so we call it hemolymph and once hemolymph on that near the head from the dorsal vessel is ejected into which cavity hemo coal right and once this fluid is present in hemoglobin what it will do it will pass through the interconnecting different sinuses and service the cells directly this fluid will go directly to the cell service them what is the service providing the cells with nutrients and removing the metabolic waste and then it come backward and again it is taken up and this system moves on such kind of open circulatory system it is not very efficient system it’s not a great system but it’s not super duper right performer but still it’s okay for our little insects right because it is okay for the smaller organisms with relatively less metabolic rate or metabolic needs the only problem which is here i am talking about is that because the system is too slow it cannot carry gases because gases need to be transported very rapidly so for that purpose the hemolymph is not designed to transport the gases so hemolymph does not have respiratory pigments like hemoglobin that is why it’s not red right it may be white or it may be gray or maybe bluish or it may be yellowish whatever depending upon the depending upon the organisms okay but here for the gas transport we have a special system what is that system so now we know advantages and disadvantages of open circulation main advantages that very little energy is required to keep on the fluid fluid circulating disadvantage there is very slow movement of the fluid so it cannot due to the slow movement there are three problems number one problem that it cannot transport gases with enough speed number two it if organism is too big it cannot effectively take the nutrients and other substances for distant organs right so it feels in larger organisms it cannot sustain this kind of system cannot sustain the life of cells in the larger organism with high metabolism is that right another thing this is slow moving fluid but as compared to the total size of the organism hemolymph is in big amount you know in one insect in a given insect in a typical given insect 50 to 60 percent of the volume is hemolymph so it means there is very big volume which is slowly slowly moving but if we come to the human beings if your weight is 70 kg you have about 5 liters of blood not 40 liters of blood so what we do here the volume is too big but when systems become efficient as we will see in closed circulatory system the advantage is we take less fluid right percentage wise total volume of the organism and volume of the circulating fluid we take less fluid but move it high efficiency and use more energy to move this fluid and keep it within the tubes and exchange the fluid with the nutrient substances or metabolic waste or other substances with the interstitial fluid this requires a high energy but it is so rapid it can sustain high metabolisms it it can go to distant limbs limbs distant organs so closed circulatory system can and is suitable for bigger organism with more rapid metabolism and this is considered more effective circulatory system okay after the break we will talk about second part that is we have discussed about the fish fish no sorry insect circulatory system we have not discussed the total structure of the insect just circulating system after that i will give you an example of closed circulatory system closed circulatory system which is with single loop right we’ll discuss that is classically present in fish right so after this break in the second part of the lecture we’ll talk about single closed circulatory system as present in fish after that we’ll take another break and then we’ll talk about the real lecture the comparison between open and close circulatory system once you are crystal clear about that then we’ll come to more advanced circulatory system we’ll talk about our dear friend frogs we’ll talk about yes our real friends human beings then you will know that your beloved girl a boy what kind of circulatory system she or he has okay let’s have a break thank you

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