Have you ever wondered what titanic work our bodies do every day to ensure metabolism in the body? How and where is primary urine and secondary urine formed, what are the mechanisms of regulation of these complex processes, what happens to the body when they are disturbed? Consider these issues in this article in more detail.
Introduction
Metabolism is the only source of energy and nutrient substrates for all living organisms, including humans. And their main carrier is blood. However, in the process of metabolism, not only the necessary for us, but also unnecessary, unnecessary or even toxic metabolites are formed, which must be released back into the environment. There are 4 ways to do this: with expiratory air, with skin secrets, through the intestines and kidneys. Here we will consider the last mechanism in more detail, because most of the correct metabolism in our body, and, therefore, its provision with all necessary substances, depends on it.
What is the importance of kidneys in the body?
The kidneys, as you know, is normal - it is a paired organ located extraperitoneally in the lumbar region of a person. It is this body that is responsible for the release of all toxins and metabolites of the body that are in the blood and do not enter the bile, and for electrolyte balance. In addition, some hormones are synthesized in them and one of the main mechanisms of blood pressure regulation is located - the renin-angiotensin-aldosterone system, which, due to special juxtaglomerular cells in the renal corpuscle arteriole, reacts very sensitively to this indicator. The parenchyma of this organ consists of millions of nephrons, in the capillary glomeruli of which primary urine forms, and in the tubules its concentration is up to secondary.
What is everything based on?
This process is multi-stage and is based on the concept of a gradient, that is, the difference between the quantities. So, the pressure gradient between the bringing and carrying arterioles regulates the amount of urine excreted, and therefore the value of the volume of circulating blood and blood pressure. And the gradient of the concentration of ions and the permeability of the walls of the tubules for them provides electrolyte balance in our body. Thus, the kidneys are a vital organ, as well as the only correct answer to the question: “How and where is primary urine formed?” If we talk more about the structure of the nephron, then two main parts are distinguished in it: the renal body (capillary glomerulus + outer Bowman-Shumlyansky capsule) and tubules (descending - proximal convoluted straight line, Henle loop, ascending - distal straight and convoluted). How and where does primary urine form in this complex system? Pretty simple, if you look.
How it works?
So, all processes occur precisely in the structures of the nephron through sequential mechanisms. In fact, primary urine is a fluid obtained by filtration from the cellular elements of the blood, and this happens in the renal body. Due to the fact that the diameter of the arteriole-bearing nephron is twice the diameter of the efferent, the blood is pumped under high pressure into the Bowman-Shumlyansky capsule, and under the influence of the same force it enters the capillary glomerulus. At the same time, cellular elements and coarse-grained molecules do not pass the barrier of the walls of blood vessels, and thus they exit the capsule back along the efferent arteriole. This is how and where primary urine is formed. And this process is repeated constantly, every second, because to maintain the viability of our organs and tissues, the blood circulates continuously, passing through the kidneys as well.
Somewhat more detailed
Thus, per day this organ passes through itself up to 1700 liters of blood, from which primary urine is formed (150-170 liters), that is, 1 liter out of every ten. In this case, enough fluid must be excreted from the body, because every day a person consumes about 2-3 liters of water, plus an additional half liter is formed during metabolic processes. And since primary urine is obtained by the simplest filtration of blood through membranes, it is practically plasma, but without large molecules. But unlike the final one, many ions and glucose are also included in the composition of primary urine, since they easily penetrate the vascular wall. Further, when it passes through the tubule system, reabsorption of water, electrolytes and, most importantly, glucose occurs. That is why, when a protein and sugar are found in urine analysis, the doctor will certainly suspect the pathological condition of the body.
Diseases
The kidneys are exposed to many infectious agents, their own antibodies, and parasites. So, a terrible disease is glomerulonephritis, which affects, first of all, nephrons, where primary urine is formed. Further, the inflammatory process goes to the tubules, and therefore, in the analysis of urine, a large amount of protein and electrolytes is found.
The most common pathology is pyelonephritis - an inflammation of the pyelocaliceal system of an infectious nature, that is, sections of the kidney that drain urine into the ureter already. At the same time, the parenchyma suffers slightly, so protein is found in small quantities, but bacteria and white blood cells - in significant. In addition, nephritis of various nature occurs during systemic pathologies of the body (amyloidosis), diseases of the cardiovascular system (atherosclerosis, arterial hypertension, thrombosis), metabolic disorders. There are also congenital malformations of the urinary system. Thus, the kidneys are extremely susceptible to pathological changes, and since their role in the body is vitally high, their health should be taken care of from a young age.