How Is Blood Pressure Generated?

How Is Blood Pressure Generated?

The left lower chamber of the heart (ventricle) receives oxygenated blood from the lungs and pumps it throughout the body. The heart fills with blood between heartbeats. This phase in the heart cycle is called diastole. When the heart pumps to push blood throughout the arteries, this phase is called systole. You can place your fingers on your neck or the inside of your wrist to detect your heartbeat. The pulse you feel is the contraction of the heart's left ventricle.

Several factors influence blood pressure. Blood volume and blood vessel wall behavior are two important determinants of blood pressure. The more blood pumped with each heartbeat, the higher the blood pressure. The presence of stiff or narrow artery walls that resist blood flow also increases blood pressure. Having lower blood volume and open, flexible arteries decreases blood pressure.
Baroreceptors are small nerve cells within arteries close to the heart that help regulate blood pressure. Baroreceptors communicate with the kidneys, arteries, veins, and heart to increase, decrease, or maintain blood pressure, as needed. The function of the baroreceptors is to ensure that sufficient blood reaches the organs and tissues of the body.
If blood pressure becomes too low, baroreceptors send signals to the heart telling it to beat faster and pump more blood per minute. The result is blood flow increases and blood pressure rises. If blood pressure becomes too high, baroreceptors send signals to the veins instructing them to expand and store more blood and return less blood to the heart. The result is blood flow decreases and blood pressure becomes lower. Conversely, veins can become narrower and return more blood to the heart, which increases blood pressure.
Baroreceptors communicate directly with arteries when blood pressure is too high or too low to bring it into a more appropriate level. Baroreceptors tell arteries to constrict when blood pressure is too low to help raise blood pressure. Baroreceptors tell arteries to relax when blood pressure is too high to help lower blood pressure.
Kidneys participate in blood pressure control by regulating urine production. When kidneys pull more water out of the blood, blood pressure decreases. When the kidneys decrease urine output, water remains in the blood and blood pressure increases. The action of the kidneys on blood pressure is slow -- acting over hours to days -- compared to baroreceptor control and other systems that influence blood pressure very quickly.
Lower blood pressure is a good thing as long as it doesn't cause symptoms that could damage organs and tissues of the body. Many people live with low blood pressure but they don't experience any symptoms. If that's the case, the low blood pressure is of no consequence. However, others who have low blood pressure experience dizziness and light headedness. This is an indication that insufficient blood flow is reaching the brain. This, in turn, can lead to weakness, nausea, confusion, and blurry vision. Low blood pressure can affect other organs leading to shortness of breath, fainting, blacking out, chest pain, and cool, clammy skin.
Low blood pressure may be induced by conditions that decrease tension in artery walls or decrease blood volume. Dehydration and bleeding are two examples of conditions that reduce blood volume. Conditions that reduce the amount of blood pumped by the heart -- such as cardiomyopathy and heart attack -- may be associated with lower blood pressure. Injuries to the spinal cord and side effects from certain medications can also reduce blood pressure.
Proper functioning of the central nervous system is necessary to maintain adequate blood pressure. The vagus nerve and adrenaline system of the body work together to affect blood pressure. When the vagus nerve is overstimulated, veins expand, insufficient blood returns to the heart, and blood pressure may decrease. Vasovagal syncope is a term for a type of fainting that occurs when the vagus nerve is overstimulated. Vasovagal syncope may happen to those who are sensitive to pain or cannot stand the sight of blood. The vagus nerve is overstimulated in these cases and fainting occurs. This type of fainting may even occur when straining to urinate or while having a bowel movement.
Conditions not associated with the neurological system may cause low blood pressure. Anything that causes a loss of fluids, including dehydration from diarrhea, vomiting, or bleeding may cause low blood pressure. Adrenal gland dysfunction, pregnancy, and blood loss may lower blood pressure as well. more  

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Thanks Brij ji. more  
Thanks Durga ji. What you have written is absolutely correct and I have also read this article. more  
I read an article in a news paper of the results of the latest research on cholesterol and heart attacks. The research claims that cholesterol has nothing to do with heart related problems. And that cholesterol levels have no direct connection with consumption of oils, meats, eggs and even fried foods and butter. In fact it has recommended consumption of fat and butter and eggs without any hesitation. Cholesterol is produced in the liver and liver is the main culprit for increased cholesterol. Cholesterol is essential for the body tissues to function smoothly. Every research paper adds more confusion to a common man's already confused information on body functioning and medications etc! more  
Dear Mr Sathyaprakash Nair , you have mentioned -When the arteries become hardened and narrowed with cholesterol plaque and calcium (atherosclerosis), the heart has to strain much harder to pump blood through them. As a result, blood pressure becomes abnormally high. I wish to understand since Cholesterol hardens the Arteries , we should avoid intake of items having Cholesterol ie Animal Products then Arteries of Vegetarian People should not become hard . Pl. advise how can we judge hardness of arteries . what is the role of Triglycerides from veg Oils etc & cholesterol produced by the Liver to meet the Body Requirements & external sources only making up the shortfall . So how to strike a bal. After blockages of my all 3 main arteries I am on ZERO Oil Diet since March 2016.but some people /Drs advise that Cholesterol is a must for body & I must take Virgin Veg Oils ( Not Chemically Processed /refined oils ) + Pure Desi Ghee to a certain extent . What are your comments & advice for optimum quantity pl. Coming to Calcium , Milk one of main source of Calcium is recommended for the benefit of strong bones but it you say causes Calcium deposit in arteries of Entire Body but the effect is more noticed in Heart Arteries which are Narrow & are Narrower in case of Indians as compared to other Countries . So here too we have to strike a bal. Supposing we infuse some Scale removal chemicals in Blood , like Ethylenediaminetetraacetic acid (EDTA), , it should be possible to dissolve the scale & open up the scaled arteries . But practically I hv seen after 20infusions of EDTA + Vitamins there is not much difference ,. Also certain items like Juices of Ginger / Garlic / Lemon ( Equal Parts with equal qty . of Apple Cider with honey are supposed to remove Calcium from Blood Circulation but I hv not noticed any change in Blood Calcium . The Normal value of blood Calcium are 8.80-10.6but mine is around 9.02-9.08 but all my 3 arteries got blocked upto 95,90& 85 % pl . The deficiency is bad for bones & excess may narrow arteries & Kidney so how to optimise & keep a bal. pl Once my arteries were blocked I took 35 sittings of ECP ( External Counter Pulsations ) but my LEVEF which was 60% in Dec.2015 has reduced to 50% in Dec 2016ie after the treatment , ie Zero Oil + Medicines + daily walk of 45 mins . Yes the breathlessness problem in Dec 2015 is not there & I hv still to walk slowly ie 3 KMs in 45 mins. People say whatever Collaterals were to open had already opened & that's why my LVEF was 60 was in 2015 at age of 78 & now there is going to be hardly any effect of EECP undertaken in March 2016 . May I hv your comments on the above issues & your experience about the same pl more  
High blood pressure (hypertension) and high cholesterol also are linked. When the arteries become hardened and narrowed with cholesterol plaque and calcium (atherosclerosis), the heart has to strain much harder to pump blood through them. As a result, blood pressure becomes abnormally high. Eating low-fat foods is just one part of a healthy diet to help your heart and blood pressure, there are a number of others that will help to lower your risk of heart attack and stroke: Eat less salt to lower blood pressure. more  
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