|Posted by firstname.lastname@example.org on September 23, 2015 at 2:05 PM|
Youtube Link: https://www.youtube.com/watch?v=GWZ8xoI_ezA
If you lined up all the blood vessels in your body, they would be 95,000 kilometers long. And every day they carry the equivalent of over 7,500 litres blood though that's actually the same 4 or 5 litres recycled over and over delivering oxygen and precious nutrients like glucose and amino acids to the body's tissue.
All that blood exerts a force on the muscular walls of the blood vessels. That force is called blood pressure and it rises and falls with the phases of the heartbeat. It is highest during systole when the heart contracts to force blood through the arteries. This is your systolic blood pressure.
When the heart is at rest between beats, blood pressure falls to its lowest value, the diastolic pressure. A typical healthy individual produces a systolic pressure between 90 and 120 millimetres of mercury and diastolic pressure between 60 and 80. Taken together a normal reading is a bit less than 120/80.
The blood traverses the landscape of the body through the pipes of the circulatory system. In any plumbing system several things can increase the force on the walls of the pipes: the properties of the fluid, extra fluid or narrower pipes. So if the blood thickens, a higher pressure is needed to push it. So the heart will pump harder. A high-salt diet will lead to a similar result. The salt promotes water retention and the extra fluid increases the blood volume and blood pressure. And stress like the fight-or-flight response releases hormones like happen epinephrine and nonepinephrine, that constrict key vessels, increasing the resistance to flow and raising the pressure upstream.
Blood vessels can usually handle these fluctuations easily. Elastic fibers embedded in their walls make them resilient. But if your blood pressure regularly rises above about 140/90, what we call hypertension and stays there, it can cause serious problems.
That's because the extra strain on the arterial wall can produce small tears. When the injured tissue swells up substances that respond to the inflammation like white blood cells collect around the tears. Fat and cholesterol floating in the blood latch onto, eventually building up to form a plaque thats stiffens and thickens the inner arterial wall. This condition is called atherosclerosis and it can have dangerous consequences. If the plaque ruptures, a blood clot forms on top of the tear, clogging the already narrowed pipe. If the clot is big enough it can completely block the flow of oxygen and nutrients to cells downstream.
In vessels that feed the heart, that will cause a heart attack when oxygen deprived cardiac muscle cells start to die. If the clog cuts off blood flow to the brain, it causes a stroke. Dangerously clogged blood vessels can be widened by a procedure called an angioplasty.There doctors thread a wire through the vessel to the obstructed site and then pass a deflated balloon catheter over the wire. When the balloon is inflated it forces the passageway to open again.
Sometimes a rigid tube called a stent is placed in the vessel to help hold it open, letting the blood flow freely to replenish the oxygen starved cells downstream. Staying flexible under pressure is a tough job for arteries. The fluid they pump is composed of substances that can get sticky and clog them. Your typical healthy heart beats about 70 times a minute and at least two and a half billion times during an average lifetime. That may sound like an insurmountable amount of pressure but don't worry your arteries are well suited for the challenge.
See Testimonials on Hypertension Here.