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Information on Blood Pressure Regulation in the Body

Dhanashree Patane
There are many elements and processes that enable your body to maintain the flow and pressure of blood.
Blood pressure and our health have a deep relation. Blood is an important composition of human body and is the fluid that the heart pumps throughout the body. This flow of blood has a certain velocity, while it travels through and to the many organs and blood vessels. This velocity and flow of blood creates pressure on organs and vessels it travels through.
This is referred to as the pressure of blood. To define blood pressure in scientific terms, it is the calculation and measurement of the amount of pressure exerted on the artery walls, as the heart pumps blood. Now blood pressure is measured as diastolic pressure and systolic pressure. 
Diastolic is the low recording of blood pressure, when the heart is relaxing between every beat and as the arteries relax, while systolic determines the high recording, when the pressure is more, as the heart forces the blood out to the arteries, that is, pumps blood. 
The factors that determine blood pressure are the force that pushes the blood through the arteries, the size or flexibility of the arteries, and the amount of blood that is pumped, the thickness or viscosity of the blood. These were the internal factors determining blood pressure, while there are many external factors that can affect blood pressure.
Blood pressure can change with a person's mood like anger, depression and stress. Some other causes of fluctuation in blood pressure are physical activity like exercise, food and diet, certain diseases, obesity, alcohol, etc. When this happens, the blood pressure can change, go high or low. 
The ideal blood pressure should be 120 over 80, that is, systolic - 120 and diastolic - 80. If the range goes high or low, it can cause health complications. In these conditions the body has its own way of regulating the blood pressure. And certain changes are executed by the organs and blood vessels to balance out the flow of blood.

How Does Your Body Regulate Your Blood Pressure

Regulation of blood pressure needs to be maintained so as to prevent damage to the blood vessels and to make sure that accurate amount of blood is delivered. The body will self regulate the flow of blood at all times during fluctuation in the pressure. This is achieved by:

Role of Arteries

The carotid artery has sensory neurons called baroreceptors that are sensitive to changes in the blood pressure (BP) in arteries. They signal the nerves in the brain to balance the heartbeat according to the increase/decrease in pressure. When BP rises, the arteries and blood vessels widen and create more space for blood flow to decrease the BP. 
They will also store more blood in them, so that less blood is pumped by the heart. Similarly, in a contrasting situation, the blood vessels narrow down to increase the blood flow and pressure. Arteries and veins store less blood so that more blood gets back to the heart for pumping.

Role of the Central Nervous System

The aorta or the heart alters the rate of pumping with change in blood pressure. If the blood flow is high, the heart will beat slowly. The parasympathetic vagus nerves send signals to the cardiac center to decrease the rate of pumping blood. If the blood flow is low, the heart starts pumping more blood, that is it beats faster.
This is made possible by the cardiac center, that sends neuro signals to the sympathetic cardiac nerves to pump more blood and faster. The size of the blood vessels is regulated by the vasomotor center.
This is where the nerve signals are sent from. The vasomotor nerves carry these signals and reduce or increase the diameter of the blood vessels. So as a result blood pressure is regulated.

Role of Kidneys

Renin-angiotensin-aldosterone system, also known as RAS, is the mechanism behind the role of the kidneys in regulating blood pressure. The kidneys have cells called the juxtaglomerular cells. These cells are responsible for secretion of the enzyme renin, which is further responsible to convert the blood plasma into certain protein.
This protein signals the blood vessels to shrink. Certain enzymes form hormones in the kidney, these hormones act as controllers of water and sodium retention in the body. Sodium is an important element for the balance of fluid in blood vessels. This leads to lesser blood supply to the kidney and lesser production of urine.
Due to the retention of water, the blood volume increases. This process increases the blood pressure. Similarly in the case of high blood pressure, the hormones signal less retention of sodium and water, which in turn signal the blood vessels to expand. This helps in lowering the blood pressure.
To summarize on how does the body regulate blood pressure, we can say that, all these organs and the nervous system play a major role in adapting their mechanisms according to the fluctuation in the blood pressure.
Many hormones too are involved in this process. We all thought of blood pressure as a simple term, ever thought there would be such a complex contribution by your body to regulate it?