The Heart & The Cardiac Cycle

The heart is a pump

The Circulatory System comprises of 3 main parts:
1) Medium: Blood
2) Pump: Heart
3) Tubes: Blood Vessels


We have already learnt about blood (medium) and its various components (there are 4 if you remember) and we have learnt about blood vessels (tubes) and why each of the 3 different blood vessels: arteries, veins and capillaries have different structures so that they can serve different functions. (*Remember this link between Structure & Function)


Now, let us focus on the ***HEART***.


We have learnt about the structure of the heart: the 4 chambers, which blood vessel goes into the heart at which specific location of the heart, the direction of blood flow in the heart, the septum: and why do we need the septum, the valves located in the heart and vessels leaving the heart (you have learnt about 4 valves in total: can you name them and place them at their exact positions in the heart?), what is the function of these valves, how to distinguish between the right side of the heart and the left side and the reason as to why it is so, you have seen the coronary arteries that bring oxygen and food to the heart  ...


Remember that Biology is a very logical science. There is a reason for everything under the sun, that one of the main principles underlying Biology is the link between STRUCTURE and FUNCTION. And after all our lessons so far, I hope that I have been able to show you that, that for *everything, there is a reason why it is structured as such. (*in Biology, there are always exceptions... thus, for almost everything!) So, always try to see this link when you learn. 


In our next lesson, we will study, in greater detail, the Cardiac Cycle. I will introduce you to the various diagrams that people draw to interpret the Cardiac Cycle and I will explain to you in greater detail how exactly our heart contracts and relaxes to pump blood around our body, very efficiently, from when we were in our mother's womb as a foetus, till the last day of our lives. Our heart, never stops pumping. 


That is why learning about the heart and how it works is no doubt interesting AND important.