IGCSE Biology Chapter 9 Transport in Animals

so works hi welcome back today we are talking about the work in chapter 9 which is transport in animals so how does our body transport substances such as fluids and molecules around well it does this by making use of our complex circulatory system our circulatory system is network of blood vessels which transports blood throughout our bodies now valves control the flow how it works is so blood normally flows in this direction this is our blood vessel and over here we can see the valves these are our valve leaflets and they allow the blood to go through because as you see they are fault they fold open averse away if blood tries to flow in the wrong direction which will be this way the blood will push up against these vowels and this will resolve them to closed and shut that's not allowing blood to flow in this direction so we have what is known as double circulatory system what that means is that blood is found through our heart twice and to complete one circuit let's take look at what that looks like this is our double circulatory system blood flows into the right atrium it flows it goes to the right ventricle from the right ventricle it's pumped to the lungs here blood is oxygenated and this oxygenated blood travels back to the heart to the left atrium it's pushed into the left ventricle when elect ventricle contracts and push this the blood to the rest of the body at the body the blood gives off the oxygen so oxygenated Charles to the body our body takes up oxygen from the blood then our deoxygenated blood returns back to the right side of the heart to the right goes to the right ventricle again and goes back to the lungs this is one circulate or one cycle in our circulation story system now fish for example have they don't have double circulatory system from the heart of that is pumped to the gills whit's oxygenated year the oxygenated blood goes to the body where the body takes up the oxygen and deoxygenated blood travels back to the heart so blood passes through the hearts only once on cycle alright so here we've got our heart don't get overwhelmed by all of these labels you do not need to know them or I've underlined the ones in red which are the ones we will be looking at so let's talk about cardiac cycle or heart blood travels through the heart yeah we've got our right side of the heart and here we have our left side of the heart you can see the wall of the left side of the ventricle is much thicker than the right side you can see the size and this is one way in which you can determine which side of the heart you're looking at if you compare the two sides you can see that the thicker side will be your left side of the heart alright so how it works is blood flows in through the superior vena cava as well as the inferior vena cava this is deoxygenated blood that's come from the brain and from the body so the blood flows into the right atrium the blood goes to the right ventricle by flowing through the atrioventricular or the tricuspid valve then the right ventricle contracts and this pushes blood through the pulmonary valve into the pulmonary artery this is one of the few arteries that carries deoxygenated blood this Audrey goes to the right and the left lung here blood will get oxygenated and returned back to the heart in our pulmonary veins these are one of the few veins in the body that carries oxygenated blood once blood is in - in the left atrium it all goes through the left atrioventricular or mitral valve into the left ventricle in the left ventricle the blood will follow the ventricle and the ventricle wall our contract this will same blood and really high pressure out into the singing altar where the blood will go to the body and to respiring tissues after blood has gone through the body it will return back through the either the inferior or the superior vena cava now coronary heart disease or HD is the disease that affects the currently arteries of the heart muscle when these arteries become blocked or become the lumen becomes narrowed because of the follow-up of plot then the heart muscle does not get the oxygen supply that it means and this this is basically career or disease if the colonel autism are completely blocked this is known as heart attack factors that increases the risk of coronary artery disease smoking's and time bad diet lack of exercise stress and certain genes so when we measure our pulse rate we are actually heart rate indirectly our portrait is caused by the expansion and relaxation of our paula trees as blood as pushes through them it's important to note that when oxygen demand increases our hardware will increase as well to deliver this oxygen to muscles now our pacemaker cells which is patch of muscle cells in the heart actually control the harder they do this by sending out an electrical signal over the myocardial site which is the muscles of the heart and this electrical signal causes these muscles to contract and this way this little patch of cells actually controls the heartbeat by sending out signals or pulses of electrical currents here we have our sign of atrial node which contains the pacemaker cells of the heart signal to increase our heart rate would be when our pH actually decreases and our muscles produce city provide products and when this acidity was our pH to decrease our heart will get the signal to increase the heart rate and this will increase oxygen flow to the tissues so let's take look at our blood vessels we have arteries which carry fresh oxygenated blood from the heart to the body when the arteries gates to the tissues they start to branch out and form smaller vessels these are known as our capillaries and they've got very thin walls our watches have everything strong elastic walls to regulate the heartbeat because as the heartbeat that is pushed to and the wall stretches and then it contracts and this evens out our pulse but now when we look at our capillary state of branches of our and they are very thin-walled missiles and some of them even get that small that only one red blood cell can squeeze through the amount of time this allows very short distance for oxygen to diffuse to the tissues or the cells outside the capillaries so the oxygen will be very close to the cell of tissue because the capillary wall in between is very thin once the blood has gone through the tissue at the end of the capillary babe or mater work these batteries will start to come together to form one bigger vessel again which is known as vein and things do not have as strong elastic walls they have thinner walls but they've got bigand lumen so that blood can flow easily through backs in the heart they also have an valves to prevents blood from flowing in the wrong direction that's not allowing blood to flow in this direction sorry table 9.1 this contains really critical information that you absolutely need to know now let's take look at blood blood is made up of our plasma our white blood cells and our red blood cells as well as platelets now plasma is the fluid portion of life it's liquid with cells suspended in it as well as other dissolved substances such as our Meyer acids red blood cells do not have nucleus they have 5.8 disc shape which you'll see in the images this increases the surface area of the sub to allow for more greater oxygen carrying capacity red blood cells contain hemoglobin which is the red pigment that you see it causes the red color and each hemoglobin molecule has iron molecules inside and oxygen actually binds to the iron and this way red blood cells transports oxygen white blood cells on the island do have new pieces and these are often large and low what's interesting about white blood cells is they can actually migrate out of the blood vessels through little holes or gaps of the blood vessels and they go out of the vessels into tissues to help fight pathogens where they can actually engulf them or they can produce antibodies against these organisms platelets are made in the bone marrow and actually small fragments of South platelets of critical in blood clotting Samurai say on i-43 this really brings the section together so how does blood clot form well you've got cut when is cut platelets will come and aggregate at the site they will release chemicals and the tissue that mean damage will also release chemicals these chemicals cause protein called fibrin to be converted to insoluble fiber nogen fibrinogen pulls mesh like network because it actually traps red blood cells and other platelets in this network and this is what actually causes clot which is sort of like plug and stops the beam so how does oxygen actually transported in the blood well hemoglobin picks up oxygen and win hemoglobin and oxygen combined after lungs they form what's called oxyhemoglobin this is the in transported by being pumped by the heart to the body's respiring tissues here the tissues have high affinity for oxygen then the hemoglobin so oxygen diffuses to the tissues and oxyhemoglobin becomes more global again and then can travel back to the lungs to go pick up another oxygen molecule on the other hand carbon dioxide is also carried in the blood but it is carry from the tissues to the lungs to be excreted so carbon dioxide is carried out mostly hydrogen carbonate ions and some of the carbon oxide older is actually paid by the hemoglobin molecule as well so the blood takes this back to the lungs and here we breathe out carbon dioxide now let's take look at how lymph is formed our capillaries have tiny gaps in them and these gaps allow for fluid to leak out of the capillaries as well as macrophages as they are able to fit and squeeze through these gas by changing shape the fluid then becomes what is known as tissue fluid and this fluid seeps in through the cells the tissue fluid then collects at open lymphatic ducts or vessels lymphatic vessels within Ireland back to the subclavian veins where the lymph fluid is put back into circulation into the bloodstream all right well that's all for less than nine hope you guys enjoyed it let's take look at some past papers question 18 asks us the diagram shows section through the human heart which is the right Hof in tricular valve yeah we can clearly see that this side of the heart muscle is lot thicker and stronger than this side thus this must be the left side of the heart as the left side is the larger more stronger muscular wall but you can see the wall of the left side of the ventricle is much thicker than the right side so our atrial ventricular valve that is the valve between the atrium and the ventricle the name will tell you where the valve is situated so these are our atrium and these at the bottom are ventricles we also take look at the right side of the heart so year over here must be our atrioventricular valve question 17 when blood is flowing through vena cava which main blood vessel wall it flows through next so blood flows into the heart into the right side of the heart via the vena cava blood flows in through the superior vena cava as well as the inferior vena cava so which blood vessel which main blood vessel will it flow through next so the blood is coming into the heart is going into our atrium it's gonna go through the atrioventricular valve into our ventricle and then it's gonna exit the bottom of the heart via the pulmonary artery ventricle contracts and this pushes blood through the pulmonary valve into the pulmonary vein because the right side of the heart goes to the lungs via the pulmonary artery that's all for today hope you guys enjoyed this good luck with stunning and go and get those good marks