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So I have been reading about the RAAS system and I was wondering how natrium (sodium ) ions increase blood pressure.I have been looking up on the internet and have yet to find an answer.Help

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Sodium acts on the juxtaglomerular cells of the kidney, which are then activated to produce and secrete renin. Renin hydrolyses angiotensinogen into angiotensin I. Next angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II.

Angiotensin II is the product that causes the increase in blood pressure, because it is a potent vasoconstrictor. With peripheral vasocontriction the heart has more resistance to pump blood against, thus higher blood pressure. Additionally, angiotensin II stimulates secretion of aldosterone from the adrenal glands, which acts on the distal tubules and collecting ducts in the kidney to retain sodium and water, thereby increasing blood volume and thus blood pressure.

enter image description here Image: RVC 2008

This pathway is one reason why ACE-inhibitors, such as benazepril, enalapril, lisinopril, or perindopril, are used to treat hypertension (high blood pressure). With less activity of ACE, there is less angiotensin II, and blood pressure goes down. Hypertensive patients are told to consume a lower sodium diet because that will lead to less activation of the JG cells in the kidney, which will eventually result in less angiotensin II, and thus lower blood pressure.

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  • $\begingroup$ This is a thorough answer, and I like the graphic. However it's a DROP in sodium that is detected by the macula densa that ticks up RAAS. That's the whole point of the system: since water follows salt the two parameters usually have a high degree of correlation and a drop in sodium suggests a drop in blood volume. Thus the need to kick up AT2 to keep the blood pressure up when volume is low. $\endgroup$ – kingfishersfire Dec 18 '16 at 22:55
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Your body removes unwanted fluid by filtering your blood throught your kidneys, the extra fluid is eliminated in urine. Basically the kidneys uses osmosis to draw the extra water out of your blood, using a delicate balance process of sodium and potassium. When you eat too much salt it increases the sodium in your bloodstream than wrecks the delicate balance, reducing the ability of your kidneys to remove the water. So the blood preassure gets higher due to the extra fluid and extra strain on the delicate blood vessels leading to the kidneys.

Here´s a link to help more : http://www.bloodpressureuk.org/microsites/salt/Home/Whysaltisbad/Saltseffects

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The increasing of the concentration of sodium ions in blood would attract water from the surrounding tissues, because of the osmotic pressure. The increasing of the total volume of blood(it has adsorbed water) makes the blood pressure higher. That is why in summer the blood pressure decreases. In fact sweating makes us lose body salts, so the volume of blood decrease and so the pressure.

http://www.bloodpressureuk.org/BloodPressureandyou/Yourlifestyle/Eatingwell/Salt http://www.medscape.com/viewarticle/489515

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Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.

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    $\begingroup$ "I guess" is not an acceptable supporting citation for an answer. Please support your claims with links to the relevant primary literature, or at the very least from secondary sources that cite primary ones, such as Wikipedia. I'm very interested in particular to see supporting evidence for your claim that blood pressure decreases in summer. $\endgroup$ – MattDMo Jul 4 '16 at 23:26
  • $\begingroup$ Please add a reference that can be accessed (ideally through PubMed). The one from Medscape cannot be accessed. $\endgroup$ – Chris Jul 5 '16 at 8:50
  • $\begingroup$ This answer was expected at our high-school chemistry exams. $\endgroup$ – Always Confused Nov 4 '16 at 4:46

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