Quantitative changes in urine. Urine formation: primary, secondary phase, composition

This sub-process is called glomerular filtration, and it occurs when the second phase of urine production enters: tubular reabsorption. The filtered glomerular fluid moves to the renal tubules, and there useful material are reabsorbed and reincorporated into the blood, which must be carried to the organs that need them.

The renal tubules are divided into: proximal coiled tubule, distal coiled tubule and collecting duct. During filtration, organic waste is removed by expelling it from the blood plasma into the so-called urine space. But waste also moves throughout the renal tubule, starting in tubular capillaries and ending in the lumen of the tubule.

Most of these elements expelled in the urine are formed during the renal glomerulum process and also belong to that part of the fluids that have not been reabsorbed into the blood. Another part of the waste was created and carried by the cells of the renal tubules.

After passing through the tubes, the liquid enters the collecting tube, and even there water can be integrated. But it is at this time and in this place that the liquid can be called urine. These collection tubes culminate in the renal calyces, which in turn reach the renal pelvis, ureters, and bladder, where urine accumulates and waits for the desire and reflex to urinate. Urine is expelled through the urethra.

A common question people have is: Why does urine seem more concentrated or yellow than usual at certain times? As urine moves through the various ducts formed by the renal tubule, glomerular filtration changes in its composition. As already mentioned, in the latter, all those substances that can affect the body and are harmful to it are removed from the blood.

However, from this process there is an amount of water and solutes that are reabsorbed into the peritubular capillaries, and this is how more concentrated hypotonic urine is more dilute in water or hypertonic urine. This happens when a person is in a state of dehydration. The body prefers to reserve water, and renal tubules at this time, they again absorb more water than is done in normal conditions. This is why urine is produced and expelled more concentrated.

Change in urine volume

On the other hand, when there is good, the renal tubules reabsorb less water and the urine produced is excreted in a more diluted way. It is assumed that in the conditions of a normal, good and healthy person, your urine level is more or less always the same, you can say that it remains in the same range.

However, there is no doubt that there are daily factors that can affect this range, and it is there that the body reacts instantly, causing a process called hydrosaline homeostasis, which basically helps to maintain this range of urine at the same volume and level.

It should be noted and noted that higher or lower urine levels will occur depending on the needs of the body, as well as with the concentration of the same fluid. That is why various elements intervene in this process of homeostasis, which guarantee an increase or decrease in water reabsorption, depending on the environment and context.

For example, these mechanisms should help increase water reabsorption when vital fluid intake has decreased or when water loss has been increased by sweating. In this process nervous system and endocrine system interfere in some way. They help form more concentrated or more dilute urine, not to mention that it occurs at a higher or lower level. It all depends on the requirements of the body to maintain homeostasis or balance.

Management of urinary tract infections. . Written by Heidi Wiesenfelder. At any given time, about 20% of the blood passes through the kidneys to be filtered so the body can eliminate waste and maintain hydration, blood pH and correct levels substances in the blood. The first part of the process of urine formation occurs in the glomeruli, which are small groups blood vessels. The glomeruli act as a filter, allowing water, glucose, salt, and waste to pass through the Bowman's capsule, which surrounds each glomerulus and prevents the passage of red blood cells.

The fluid in Bowman's capsule is known as nephrite filtration and resembles blood plasma. It also includes ammonia-derived urea, which builds up as the liver processes amino acids and filters through the glomerulus. About 43 gallons of fluid pass through the filtration process, but most of it is then reabsorbed rather than eliminated. Reabsorption occurs in the proximal tubules of the nephron, which is absorption behind the capsule, in the loop of Henle, and in the distal and collecting tubules, which are further along the loop of Henle.

Water, glucose, amino acids, sodium and others nutrients reabsorbed into the bloodstream into the capillaries around the tubules. Water goes through the process of osmosis: moving water out of the area high concentration to an area of ​​low concentration. Sodium and other ions are not completely reabsorbed, while most of remains in the filtrate when more is consumed in the diet, resulting in higher blood concentrations.

Hormones regulate an active transport process in which ions such as sodium and phosphorus are reabsorbed. Secretion is final stage during the formation of urine. Some substances move directly from the blood into the capillaries around the distal and collecting tubules within these tubules. The secretion of hydrogen ions in this process is part of the body's mechanism to maintain the correct pH or base acid balance. More ions are secreted when the blood is acidic and less when it is alkaline.

Potassium, calcium, and ammonium ions, as well as some drugs, are also released at this stage. This is done in part by increasing the secretion of substances such as potassium and calcium when concentrations are high and increase reabsorption and decrease secretion when low levels. The urine created by this process then passes into central part kidney, called the pelvis, where it flows into the ureters and then through the bladder.

Excretion is the process by which the body removes metabolic waste from the body

In humans, this function is responsible for various organs. However, the kidney plays important role in the allocation of waste products of food metabolism. After food products digested into digestive system and are absorbed and transported to the circulatory system to be used by the cells, waste products are formed that are removed from the body through the renal system.

These substances are eliminated by the formation of urine, the main components of which are water, electrolytes, urea, uric acid and end products of hemoglobin metabolism and hormone metabolites. To perform an excretory function, the renal system has a number of structures that perform certain functions.

Kidneys: Secretory organs in which urine is produced. Cleaners: Collect the ducts that collect urine as it exits the kidney. Veiga: Organ receptor urine. Urethra: Secretory duct that drains urine out. Figure 11: Diagram of the urinary system.

The organ responsible for the formation of urine is the kidney. In the kidneys, we can distinguish three segments: the cortex, the brain, and the renal pelvis. The cortex and brain are formed by the nephrons, which are the functional unit of the kidneys and which allow the formation of urine. The pelvis corresponds to the dilated segment of the ureter and receives the already formed urine.

Since the debris must be removed from the blood, important aspect The function of the kidneys is its connection with the circulatory system. Through renal artery, which flows into small capillaries, the blood enters the kidney, which is cleaned, and then returned to the circulatory system through the renal vein.

Figure 12: Structure of a sectioned kidney to show the main internal structures. We have already mentioned that the functional unit of the kidney is the nephron. This is where the blood is filtered to extract waste. Figure 13: Structure of the nephron. How does the extraction process take place? The kidney performs its functions through several mechanisms: glomerular filtration, tubular reabsorption, secretion, and excretion through the urine.

Recall that it is the vascular element that is responsible for removing waste and other materials to the excretory tubules, returning materials reabsorbed by the kidney or synthesized for the systemic circulation, and delivering oxygen and other metabolic substrates to the nephron.

The excretion process begins in the renal corpuscle, which is formed by blood capillaries and Bowman's capsule. The glamululus, formed by a porous capillary network, acts as a plasma filter. The division is based on molecular structure. Due to this process, plasma filtration of blood is formed, which is formed during the passage of plasma without cellular elements and mostly devoid of proteins from the interior of the glomerular capillaries into the space of Bowman's capsule. This is approximately 180 liters per day.

Red arrows indicate blood flow and blue arrows indicate ultrafiltrate. If the glomeruli filter 180 liters per day, it follows that there must be resorption, since 180 liters of urine per day does not seem to be ruled out. Resorption occurs throughout the tubular system of the nephron, but is more active in the proximal tubule. Tubular reabsorption allows you to save substances that are important for the body, such as water, glucose, amino acids, vitamins, etc. Which again occur with blood. In addition, reabsorption is able to adapt to the needs of the moment, that is, it participates in the homeostasis of the internal environment.