Urea is carried in the blood to the kidneys. This is where it is removed, along with water and other wastes in the form of urine. The kidneys have other important functions. They control blood pressure and produce the hormone erythropoietin.
This hormone controls red blood cell production in the bone marrow. The kidneys also control the acid-base balance and conserve fluids.
Two kidneys. This pair of purplish-brown organs is located below the ribs toward the middle of the back. Their function is to:. The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries glomerulus and a small tube called a renal tubule. Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.
Two ureters. These narrow tubes carry urine from the kidneys to the bladder. Muscles in the ureter walls keep tightening and relaxing. There are many causes of protein in the urine, including diabetes and glomerulonephritis. Whilst your doctor will conduct a number of special blood tests, to try to determine the underlying cause, it may be necessary to undergo a kidney biopsy, to establish the exact cause of the protein.
Patients who have very large amounts of protein in the urine, greater than 3 grams , are described as having nephrotic syndrome. Patients with nephrotic syndrome frequently have swollen legs. Haematuria or blood in the urine can either be present in amounts that you can see macrascopic or in amounts that you cannot see microscopic in which it is only detected with urine testing.
Blood in the urine may not appear red but more like strong tea coloured. Blood in the urine is frequently an alarming symptom and it should never be ignored. However, it only takes a few drops of blood for the urine to turn red. There are a large number of potential causes of blood in the urine including: urine infection, kidney stones, kidney or bladder tumours and inflammation in the kidney called glomerulonephritis GN.
If you have haematuria, the first thing your doctor will do is to make sure you do not have a urine infection or bladder or kidney tumour. To do this, you will usually need to have a number of scans of the kidney and may well need a cystoscopy. A cystoscopy is a test in which a camera with a light is inserted into the bladder. If these tests are normal your doctor will then focus on determining if the blood is coming from kidney inflammation or glomerulonephritis.
This may require further specific blood and urine tests or a kidney biopsy. High blood pressure hypertension may arise due to, or as a result of, kidney disease. It is important, however, to realise that the vast majority of people, with high blood pressure, have entirely normal kidney function.
If you have high blood pressure, it is very important to treat it as it will help preserve your kidney function and reduce the risk of developing a stroke or heart attack.
Elevate Serum Creatinine - The serum creatinine is a blood test that is used to monitor kidney function. The serum creatinine may be elevated as an early sign of kidney disease long before there are any symptoms evident of kidney disease. Blood tests, identifying elevated serum creatinine, are main undertaken, as a routine, during an annual physical medical examination. If serum creatinine is elevated, it may be as a result of any of the kidney diseases discussed below.
Kidney stones occur when a tiny fragment of crystals develops within the kidney or the tube coming from the kidney, called the ureter.
A kidney stone mainly produces very severe colicky pain. The pain of a kidney stone is described as being more severe than that of labour pains. The treatment of a kidney stone will consist of pain medication initially mainly in the form of an injection. This may occur by way of a number of methods, depending on the size and position of the kidney stone. The urologist may pass a scope into the bladder and try to grasp the stone.
They may also try to bypass the stone temporarily with a stent, or may try to dissolve the stone with a machine called a Lithotripsey.
Occasionally, the urologist may be required to perform an open operation, on the kidney, in order to surgically remove the stone. Once the stones are removed, the team will attempt to determine their underlying cause.
Conditions associated with recurrent kidney stones include:. Urea serves an important role in the metabolism of nitrogen-containing compounds by animals. It is the main nitrogen-containing substance in the urine of mammals.
Urea is a colorless, odorless solid, highly soluble in water, and practically non-toxic. Dissolved in water, it is neither acidic nor alkaline. The body uses it in many processes, the most notable one being nitrogen excretion. Urea is widely used in fertilizers as a convenient source of nitrogen. It is also an important raw material for the chemical industry. Apart from mammals, urea is also found in the urine of amphibians, as well as some fish. Interestingly, tadpoles excrete ammonia, but shift to urea production during metamorphosis.
In humans, apart from being a carrier of waste nitrogen, urea also plays a role in the countercurrent exchange system of the nephrons, which allows for re-absorption of water and critical ions from the excreted urine.
This mechanism, controlled by an anti-diuretic hormone, allows the body to create hyperosmotic urine, which has a higher concentration of dissolved substances than the blood plasma. This mechanism is important to prevent the loss of water, to maintain blood pressure, and to maintain a suitable concentration of sodium ions in the blood plasmas.
The urea cycle is the primary mechanism by which mammals convert ammonia to urea. Urea is made in the liver and excreted in urine. The urea cycle utilizes five intermediate steps, catalyzed by five different enzymes, to convert ammonia to urea. The amino acid L-ornithine is converted into different intermediates before being regenerated at the end of the urea cycle. Hence, the urea cycle is also referred to as the ornithine cycle.
The enzyme ornithine transcarbamylase catalyzes a key step in the urea cycle. Its deficiency can lead to accumulation of toxic levels of ammonia in the body.
The first two reactions occur in the mitochondria, while the last three reactions occur in the cytosol. Urea Cycle : The urea cycle converts ammonia to urea in five steps that include the catalyzation of five different enzymes. Birds and reptiles have evolved the ability to convert toxic ammonia into uric acid or guanine rather than urea.
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