Excreting Urine in Kidney In the body there are a pair of kidneys located on the right and left adjacent to the waist bones.The shape of the kidney is like a pea with a length of approximately 10 cm. a. Kidney Structure The kidney consists of two layers, namely the outer layer called the cortex and the inner layer called the medulla. The cortex contains millions of filtering devices called nephrons. Each nephron contains a Malpighian body (renal body). Malpighian bodies are composed of Bowman's capsule and glomerulus.The medulla contains convoluted tubules (renal tubules) which open into bulges in the renal pelvis (kidney chamber).There are three types of renal tubules, namely convoluted tubules the proximal channel which channels the filtrate from Bowman's capsule, the loop of Henle which is a long channel that plunges downwards then turns upwards, and the distal convoluted tubule which channels the filtrate to the collecting duct.So, the filtrate journey can briefly be written as follows.Bowman's capsule, distal convoluted tubule, loop of Henle, proximal convoluted tubule, collecting duct, there are two types of nephrons in the human kidney, namely cortical nephrons and duxtamedular nephrons. Cortical nephrons consist of glomeruli which are relatively small in size and are always located in the cortex or outside the medulla. Meanwhile, the duxtamedular nephron has a large glomerulus and has a loop of Henle that extends into the medulla. The loop of Henle consists of the descending loop of Henle which transports filtrate from the proximal convoluted tubule and the ascending loop of Henle which transports filtrate to the distal convoluted tubule. These duxtamedullary nephrons play a role in regulating urine concentration so that the urine excreted is hypertonic compared to body fluids. In the kidneys, the process of forming urine occurs. Urine is formed through a series of filtration processes (filtering) of toxic waste substances, reabsorption and secretion, as well as augmentation (collection) of waste substances that are no longer needed. b. Urine Formation Process First, blood containing water, salt, glucose, urea, amino acids and ammonia flows into the glomerulus to undergo a filtration process. This process occurs due to blood pressure due to the influence of the expansion and contraction of the arteries that extend to and leave the glomerulus. The end of the filtration from the glomerulus is collected by Bowman's capsule and produces glomerular filtrate or primary urine. Normally, every day Bowman capsules can produce 180 L of glomerular filtrate. Glomerular filtrate or primary urine still contains many substances the body needs, including glucose, salts and amino acids. This glomerular filtrate is then transported by the proximal convoluted tubule. In the proximal convoluted tubule, substances that are still useful are reabsorbed. Such as amino acids, vitamins, and several ions, namely Na+, Cl–, HCO3 –, and K+. Some of these ions are reabsorbed by active transport and others by diffusion.The reabsorption process continues as the filtrate flows towards the loop of Henle and the distal convoluted tubule. In general, reabsorption of substances that are still useful for the body, such as glucose and amino acids, takes place in the renal tubules. However, if the concentration of these substances in the blood is high, the tubules are no longer able to absorb these substances. If this happens, these substances will be excreted in the urine.Apart from reabsorption, secretion also takes place in the tubules. Such as K+, H+, NH4 are secreted from the blood into the filtrate. In addition, drugs such as penicillin are also secreted from the blood. The secretion of hydrogen ions (H+) functions to regulate pH in the blood. For example, if the blood is too acidic, hydrogen ions are secreted into the urine.K+ secretion also functions to maintain homeostatic mechanisms. If the concentration of K+ in the blood is high, it can inhibit impulse stimulation and cause muscle and heart +contractions to decrease and weaken.Therefore, K+ is then secreted from the blood into the renal tubules and excreted with urine. When the process of reabsorption and secretion occurs along the renal tubules, the concentration of urine automatically takes place. For example, salt concentration is balanced through the process of salt reabsorption. In the loop of Henle there is NaCl in high concentrations. The presence of NaCl functions so that the fluid in the loop of Henle is always in a hypertonic state.The wall of the descending loop of Henle is permeable to water, but impermeable to Na and urea.This high Na concentration causes the filtrate to be pushed into the lower loop of Henle and water moves out by osmosis.In the lower loop of Henle, the permeability of the walls changes. The walls of the lower loop of Henle become permeable to salt and impermeable to water.This situation encourages the filtrate to move into the ascending loop of Henle.Water that moves out of the descending loop of Henle and water that moves in while in the ascending loop of Henle makes the filtrate concentration isotonic.After that, the filtrate is pushed from the renal tubule to the collecting duct. The collecting duct is permeable to urea. Here the urea comes out of the filtrate by diffusion.Likewise, water moves out of the filtrate by osmosis. This release of water causes the urine concentration to be high.From the collecting duct, urine is carried to the renal pelvis.From the renal pelvis, urine flows through the ureters to the urinary bladder (urinary bladder) which is a temporary storage place for urine. Urine is stored in the bladder (vesicaurinaria) until it reaches approximately 300 cc. ThenThrough the urethra, urine is excreted from the body. ExpenditureThis urine is regulated by the sphincter muscle. regarding the human urinary system.The formation of urine from blood plasma causesthe occurrence of many changes in substance content. c. Things that Affect Urine Production Health experts say that by excreting a lot of urine the body becomes healthy. It is said to be healthy if you excrete approximately 1 liter of urine a day. The amount of urine excreted each day is influenced by diuretic substances, temperature, blood concentration and emotions.Diuretic substances are able to inhibit the reabsorption of Na+ ions. As a result, the concentration of Anti-Diuretic Hormone (ADH) decreases so that water reabsorption becomes inhibited and urine volume increases.An increase in temperature stimulates abdominal contraction so that glomerular blood flow and filtration decrease. In addition, increasing temperature also increases the rate of respiration. This causes the volume of urine to decrease.If we don't drink water all day, the concentration (level) of water in the blood will be low. This will stimulate the pituitary to release ADH. This hormone will increase water reabsorption in the kidneys so that urine volume decreases. Likewise, times of tension or anger can stimulate changes in urine volume. d. Kidney Disorders and Abnormalities The function of the kidneys as a means of excretion can be disrupted by various reasons which can cause disease and disorders in the body. The various diseases and disorders are as follows.Nephritis is kidney damage to the glomerulus due to infection with Streptococcus bacteria. This infection can cause urea and uric acid to re-enter the blood and disrupt water reabsorption. If urea and uric acid enter the blood it causes uremia, and if water reabsorption is disrupted it will result in edema or swelling of the legs due to water accumulation.If this nephritis is not treated immediately, it can result in "kidney failure", namely the failure of the kidney's function as an excretory organ. Kidney failure can be helped by dialysis.If kidney function is disrupted, the nephrons are no longer able to effectively absorb several substrates that should be absorbed, for example: albumin, protein and glucose. If someone's urine contains albumin, they are suspected of suffering from albuminuria. However, if glucose is found in the urine, it is suspected that you are suffering from glucosuria. The presence of glucose in the urine can be caused by high glucose in the blood, so that the nephrons are unable to absorb the excess glucose.High levels of glucose in the bloodstream can be triggered by a lack of the hormone insulin in the body.Kidney disorders can be caused by unhealthy eating patterns. For example, consuming too much mineral salt and consuming too little water. This can trigger the formation of kidney stones in the kidney cavity, kidney tract or bladder. If kidney stones are in the kidney tract, the urine tract will be blocked. This situation causes enlargement of one of the kidneys (hydronephrosis) because urine cannot flow out.Friction due to kidney stones causes inflammation of the urinary organs, allowing erythrocytes to be transported in the urine. If this happens then the person suffers from hematuria.