How and where the primary urine is formed: mechanisms in the norm and pathology

Have you ever wondered what kind of titanic work our bodies do every day to ensure the metabolism in the body? How and where is primary and secondary urine formed, what are the mechanisms of regulation of these complex processes, what happens to the organism in case of their disturbances? Let us consider these questions in detail in this article.

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 necessary, but also unnecessary, unnecessary or even toxic metabolites are formed that need to be released back into the environment. Ways for this 4: with air on exhalation, with skin secrets, through the intestines and kidneys. Here is the last mechanism we will consider in more detail, because it depends on most of the correct metabolism in our body, and hence its supply with all the necessary substances.

What is the significance of kidneys in the body?

Kidney, as is known, is normal - it is a paired organ, located extraperitoneally in the lumbar region of a person. It is this body that is responsible for isolating all toxins and metabolites of the body that are in the blood and do not enter bile, and for electrolyte balance. In addition, some hormones are synthesized and one of the main mechanisms of regulation of arterial pressure is the renin-angiotensin-aldosterone system, which, due to special juxtaglomerular cells in the renal corpuscle bringing the arterioles, reacts very sensitively to this index. The parenchyma of this organ consists of millions of nephrons, in the capillary glomeruli of which primary urine is formed, and in the tubules it is concentrated to the secondary one.

What is it based on?

This process is multi-stage and is based on the concept of a gradient, that is, the difference between quantities. Thus, the pressure gradient between the delivery and outgoing arterioles regulates the amount of urine released, and hence the value of the volume of circulating blood and blood pressure. And the gradient of ion concentration and the permeability to them of the tubular walls provides an electrolyte balance in our body. Thus, the kidneys are a vital organ, and the only correct answer to the question: "How and where is the primary urine formed?" In more detail about the structure of the nephron, there are two main parts in it: a renal corpuscle (capillary glomerulus + outer Bowman capsule Shumlyansky) and tubules (descending - proximal convoluted straight, Henle's loop, ascending - distal straight and convoluted). How and where is the primary urine formed in this complex system? Quite simply, if you understand.

How it works?

Thus, all processes occur precisely in the nephron structures through successive mechanisms. In fact, the primary urine is a fluid obtained by filtration from the cellular elements of the blood, and it occurs in the renal corpuscle. Due to the fact that the diameter of the arteriolar nephron is twice as large as the diameter of the nephron, blood under high pressure is injected into the Bowman-Shumlyansky capsule, and under the influence of the same force enters the capillary glomerulus. In this case, the cellular elements and coarse molecules do not pass through the barrier of the walls of the vessels, and thus they leave the capsule back along the vascular arterioles. This is how and where the primary urine is formed. And this process is repeated constantly, every second, because to maintain the vitality of our organs and tissues, the blood circulates continuously, passing through the kidneys as well.

A few more details

Thus, per day this organ passes through itself up to 1700 liters of blood, from which primary urine (150-170 liters) is formed, that is, 1 liter out of every ten. At the same time, enough fluid should be isolated from the body, because every day a person consumes about 2-3 liters of water, plus an additional half-liter is formed in the course of metabolic processes. And since the 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 primary urine, as they easily penetrate the vascular wall. Further, when it passes through the tubule system, reabsorption of water, electrolytes and, most importantly, glucose, takes place. That is why when a protein and sugar are found in the urine analysis, the doctor will invariably suspect the pathological state of the organism.

Diseases

The kidneys are exposed to many infectious agents, their own antibodies, as well as parasites. So, a formidable disease is glomerulonephritis, which affects, first of all, nephrons, where primary urine is formed. Then the inflammatory process passes to the tubules, and therefore a large amount of protein and electrolytes is found in urine tests.

The most common pathology is pyelonephritis, an inflammation of the bowel-and-pelvic system of infectious nature, that is, the kidneys that extract urine into the ureter. The parenchyma suffers insignificantly, so the protein is found in small amounts, but the bacteria and leukocytes are significant. In addition, various nephrites occur in 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 prone to pathological changes, and since their role in the body is vital, their health should be taken care of in their youth.