Blood pressure regulation of renal

The kidneys control the amount of fluid in the body. The kidneys are the main site of blood pressure regulation in the human body. The blood pressure is restricted to do with how big is the total amount of blood that circulates in the blood vessels. The kidneys are the organ of the body that regulates the amounts of liquid. This of course also affect the blood volume.


The blood pressure must be kept constant within narrow limits
Maintaining a certain blood pressure is for the functioning of the human organism is of vital importance. If blood pressure is too low, then the blood may not reach all organs. These are then not sufficiently supplied with oxygen and nutrients. The result would be an impairment, organ failure or death (for example, a shock). The blood pressure exceeds a certain limit, this would damage the vessels first and then the institutions themselves (such as stroke). The blood pressure should therefore be kept constant within narrow limits.


The amount of blood and the diameter of the vessels have an impact on blood pressure
Decisive influence on blood pressure has on the one hand, the diameter of blood vessels and other blood volume. Imagine a garden in front of cleverness. If you squeeze at the opening, so the pressure is higher and you can spray on. The same can be reached also if you turn on the faucet more and more water flows through the hose. With regard to blood pressure means: The smaller the diameter of blood vessels and the larger the volume of blood in the circulation moving, the higher the blood pressure. The same applies vice versa for low blood pressure: The more the blood vessels and the smaller the blood volume, the lower the blood pressure. For example, atherosclerosis of the vessels are narrowed by deposits. That is one reason for the high blood pressure.

Vessel diameter
Hormonal control systems regulate the diameter of blood vessels.
On both factors exert a decisive influence of the kidneys. Central control mechanism is the "renin-angiotensin-aldosterone mechanism." In the kidneys, special cells, the sodium concentration measured in the Tubulusflüssigkeit. If the concentration of sodium is too low, the renin is activated. Renin is produced in the cells of the juxtaglomerular apparatus in the kidneys. Also, a too low blood pressure and the hormones epinephrine and norepinephrine from the adrenal medulla to activate the renin. Renin causes an increased formation of angiotensin II. Angiotensin II in turn causes:

    Constriction of blood vessels
    increased thirst
    increased secretion of aldosterone and catecholamines
    Secretion of hypothalamic hormone Adiuretin (ADH) from the posterior pituitary

This combination increases the blood pressure, the sodium concentration of the blood and the blood volume. The potassium concentration in the blood decreases.




Angiotensin II, the most powerful hormone that leads to vasoconstriction, is at the end of a hormonal cascade that takes its beginning in the kidney. The starting point is the renin.

    Renin acts on a substance that is produced in the liver, angiotensinogen.
    From angiotensinogen is cleaved by the action of the renin angiotensin I.
    Another substance that the enzyme angiotensin-converting enzyme (ACE), which cleaves angiotensin I into its active form, angiotensin II

The enzyme angiotensin-converting enzyme (ACE) is a target in the treatment of hypertension. ACE inhibitors do what its name says, they inhibit the ACE enzyme. The result is that not much can be made effective angiotensin II and lowers blood pressure.

To the catecholamines, their distribution is encouraged (see chart), for example, is the adrenaline, the others increasing blood pressure in the short term effect.


Blood volume
A detailed description of sodium and water balance and disturbances in the metabolism of electrolytes can be found in metabolism and metabolic disorders in endocrinology Medizinfo ®.
The regulation of blood volume is very complex and is influenced from many sides and stimulated. The decisive factor is the sodium concentration in the blood: sodium ions bind water itself. If sodium is excreted, so that also means that the body loses water. By increased aldosterone secretion is counteracted. Aldosterone promotes the reabsorption of sodium ions from the distal tubule and increases the excretion of potassium. The blood volume increases.



Register a pressure receptors on the heart to overload.
The ANP (atrial peptide netriuretisches) does the opposite. This hormone is distributed in the heart of cells that have stretch receptors. If in the opinion of the heart too much blood volume in the cycle, then it becomes very stretched, and thus too much stress. In this case, ANP is released. It causes a decreased reabsorption of sodium. This means it is excreted more sodium and hence more water. The blood volume decreases.


The reabsorption of water is regulated by the hormone Adiuretin.
The Adiuretin or antidiuretic hormone (ADH) plays an important role in regulating the osmotic pressure and fluid volume of the body. ADH promotes the reabsorption of fluid from the distal tubule and collecting duct of the kidney into the blood. Has anyone been drinking for a long time as nothing, then the osmotic pressure increases in the blood. This means that, the concentration of blood cells in the blood increases in proportion to the liquid concentration. Blood is thicker, so to speak. By discarding Adiuretin is then delivered in the kidney increased fluid from the primary back into the blood. This increases the fluid level in the blood and the osmotic pressure falls again. The distribution of Adiuretin is also funded by angiotensin II.


The different regulatory mechanisms interact and are interdependent. In this way, the blood pressure regulation is subject to a cycle of continuous monitoring and correction.