 While visiting a doctor, you must have observed how most visits would start with a blood pressure check. So a few years back, when I went to my doctor, I was told that my blood pressure was normal, okay? And he said it was 120 over 80. I smiled at him and acted as if I understood, but in reality, I had no clue what he was talking about. I had so many questions in my mind. The first among them was, what is this blood pressure in the first place? And what is this blood pressure number? Why do we have two numbers for a single person's blood pressure, right? And the third question was, does this blood pressure have any effect on my health? So let's discuss about these questions in this video. Okay, and we will begin by talking about where blood is. Only then will we be able to measure the pressure, right? So blood is found in the blood vessels or let's just write in the arteries, because arteries take blood from the heart to all different body parts. So when the blood flows through the arteries, it exerts the pressure on the wall of the arteries as well. Right, so the push or the pressure that the wall of the arteries feel when the blood moves or flows through it is the blood pressure. So we can write that the pressure exerted on the walls of the arteries is the blood pressure. Okay, BP is the blood pressure. Simple, right? Okay, so we understood what is blood pressure. Coming back to the next question, what are these blood pressure numbers? 120 over 80, why do we have two separate numbers for my blood pressure? Well, for that, we need to have a look at our heart. So this is the pumping machine of our body, right? Blood pumping machine of our body. So when the heart pumps blood out during systole, the pressure in the arteries will be high. So let's make the arteries here. So as you can see, during systole, there is a forceful contraction of the heart that sends a wave or a forceful push to the blood into the arteries that creates a very high pressure at that moment in the arteries. That is what I'm trying to show through the animation. So the higher number or the bigger number or the number at the top is called the systolic pressure of the heart. But when the heart is not pumping or during diastole, or we also call it the time between two heart beats. So the pressure in the arteries then is less, right? So the number or the denominator here is the diastolic pressure. So here we learned that we have two separate numbers because one is the systolic or the pumping pressure and the other is the diastolic or the resting pressure. Okay, now coming back to the final and the most important question. What is the blood pressure's effect on our health? Especially what would happen if our blood pressure is high? Well, again, blood pressure lower than normal is also not good. But we will only discuss about high blood pressure because this is what our syllabus is asking. Now, when do we call the blood pressure high? The natural answer would be when it is above 120 over 80. Well, then let me tell you that a normal person with a normal blood pressure can have high or low pressure depending upon the activity of that person throughout the day. For example, let's say you're super stressed about something. Maybe around six o'clock in the morning. Okay, if we measure your pressure then it could be somewhere around 140 over 90. Your blood pressure could shoot up. But then by the evening the matter is resolved and you are happy now. Okay, you're in a normal mood. Your blood pressure will go back to the normal range. 120 over 80 or somewhere near to this normal range. So can we say that you have high blood pressure? The answer is no because it was temporary depending upon your activity or your mood or what is going on in your life at that time. But if a person has a pressure range of 140 over 90 consistently, that means this pressure persists no matter what is going on in his life, what he is doing, what his activities are, then we would say that that person has high blood pressure or the technical term is hypertension. Well now if you're wondering how can someone's mood or someone's activity affect the blood pressure, then I would recommend you to go back and watch the previous videos where we discussed about how hormones and neurotransmitters affect the heart rate. So in a stressful condition when your heart will beat faster more blood will be sent out into the arteries and the pressure there will increase. That is how the blood pressure rises. But now let's talk about what happens to a person or what happens to the arteries of a person who has hypertension. So the arteries have elastic fibers embedded in it and with a constant high pressure in the arteries for a very long time those fibers loses the elasticity. Same like the hair band that you use, the elastic rubber band to tie your hair. What happens to it after some time? It becomes loose. It no longer holds your hair efficiently, right? The same goes for the arteries. They are no longer efficient at transporting blood. And sometimes with excessive high pressure, the cells of the arterial wall gets damaged. So when the arterial wall is damaged, there will be a lot of cells that would come to the rescue or to help repair the wound. They would then deposit in that area and would narrow down the artery. As you can see, the space for the blood to flow has reduced in this area. Now if the flow continues to increase, then it can uproot the whole healing situation here. Okay? Let's say the flow of the blood is so, so high that it uprooted the whole accumulation or the deposit in that area. That can cause blood clot in that area and the blood clot can be so severe that it can completely block the artery. You see, there will be no blood moving from this side to the other side of the artery. In that case, the cells or the tissue to which the artery was carrying blood to will not receive blood and would gradually die. So this is why our blood pressures should be in the normal range. Because think about it, from the change of gases in our lungs to the filtration in our kidneys, it all depends on the blood pressure, isn't it? So maintaining a normal blood pressure is crucial for a healthy life.