The topic we have been working on in Science at the moment is called 'Heart and Lungs'. As the name suggests, this topic explores the heart and lungs as well as the blood and circulatory system. We have learnt the difference between oxygenated and deoxygenated blood, which is commonly represented by red and blue, red being oxygenated and blue representing deoxygenated blood. We learnt the function of the lungs, which is to reoxygenate the blood as it passes through on its way to the heart. The heart itself is extremely strong, pumping the equivalent of 7, 200 litres of blood each day. Comprised of four chambers known as atrium's and ventricles, which accurately makes our heart known as a four chambered heart. The blood travels into the atrium and is then pumped into the ventricle, before being pumped out of the heart and to its respective place. Valves in the lining of the artery's that lead to the heart, known as semi-lunar valves, fill with escaping blood and press together to form a seal, preventing blood from falling back into the heart. We also learnt about the two different jobs that the heart completes. The right side of the heart is responsible for pumping deoxygenated blood to the lungs to get reoxygenated and then pumping it back into the heart, to be pumped around the body. For this reason, the right side of the heart is often much weaker, the muscle not as thick, due to the fact that it only needs to be pumped to the lungs and not around the entire body. That is the job of the left side of the heart, which is constantly working to pump the newly oxygenated blood around the body. This is why the left side of the heart is visibly much stronger, because it's job is to pump blood to the entire body, which is much more strenuous. We learnt about the coronary veins which line the surface of the heart and are responsible for providing the heart with a constant source of oxygen to prevent it from becoming too strained. Finally we learn about the actual composition of blood, and the four main components which make it up. Plasma, the liquid component of blood which is responsible for transporting the nutrients around the body. Plasma makes up 55% of the blood. Next are the Red Blood Cells, or RBC. They are the cells responsible for transporting oxygen around the body. They are the only cell that does not possess a nucleus, instead possessing haemoglobin, which attracts oxygen to affix itself to the cell and gives it its read colour. They make up 45% of the blood. The remaining less than 1% is made up of leukocytes (White blood cells, WBC) and platelets. WBC are responsible for producing the necessary antibodies to help arm the immune system and fight infection. Platelets are the body's natural plaster, clotting the blood around open wounds to form scabs which prevent the wound from bleeding; they make up less than 1% of the bloods volume. That concluded our learning for this unit for the duration of 2020. We will finalise the topic with an assessment when we return in 2021.
