Everyone knows where the heart and lungs are, for example. We tend to be very interested in the heart and lungs. Because, when thinking about life, we immediately think of breathing. Yes, as long as we breathe it means we are alive, but that does not mean that we are in good health. It should be noted that all organs of the body each have their importance and their particularity. In this article, we will expose the kidneys.
The kidneys are undoubtedly poorly known organs, which we often do not know well locate. These organs are the “washing machine of the body”. They filter the elements essential to the functioning of the cells and provide several essential functions.
Where to locate the kidneys? How to describe the kidneys? What are the kidneys used for in the body? What are the different types of kidney diseases? How to take care of the kidneys? What are the risks if the kidneys do not work well? In short! Know everything in this article about the functions of the kidneys and the different types of kidney diseases.
I – Definition and Description of the Kidneys
The kidney is the organ that produces and evacuates urine. The kidneys, two in number, are the organs of the excretion of urine.
The kidneys are located under the ribs, on both sides of the spine and not in the lower back as many popular expressions suggest. This organ ensures the filtration of the blood and the evacuation via the urine of the waste of the body. He is also responsible for many elements essential to the stability of our body.
We usually have two kidneys but it is possible to live quite normally with one kidney.
We can distinguish different parts:
– Two extremities or poles: consisting of an upper extremity on which is placed the adrenal gland and a lower or caudal end
– Two sides: anterior and posterior
– Two edges: one external (convex) and one internal, which carries in its middle part the hilum of the kidney, place by which the excretory ducts leave the kidney. The hilum is also the place of passage of the vessels of the kidney: the renal artery, which is born from the aorta, brings oxygenated blood to the kidney while the renal vein recovers the blood to drain it into the inferior vena cava.
*** Anatomy of the Kidney
Red-brown in color, the kidney is shaped like a bean. In an adult, the kidney is 12 cm by 6 cm wide and 3 cm thick; it weighs about 160 gr.
*** Filtering Blood
It is through the renal artery, branch of the aorta, that the blood reaches the kidney. Thanks to the nephrons, it comes out “filtered” by the renal vein which joins the inferior vena cava. The urine formed by this filtering is evacuated by the urinary tract.
*** The Urinary Tract
As a whole, it consists of both kidneys and urinary tract (high and low). The bladder is the reservoir that stores the urine before discharge through the urethra. Urination is called urination.
*** The Adrenal Glands
As their name suggests, the adrenal glands are located just above the kidneys. They allow the secretion of hormones, enzymes and vitamins.
II – The Functions of the Kidney
The missions of the kidney are multiple:
1 – Filter Role
The primary function of the kidneys is to eliminate the toxic waste produced by the normal functioning of the body and transported by the blood. These substances are useless to the body and are toxic if they are not eliminated.
2 – Maintaining the Body’s Water Balance
Absorbed by drinking and eating, the water is eliminated mainly by the urine but also by the stool, sweat and breathing. The kidneys allow the body to maintain the amount of water it needs. Each day, they filter about 190 liters of blood but only release 1.5 to 2 liters of urine. In total, daily entries and exits of water are balanced.
In addition to their elimination function, the kidneys reabsorb the water and minerals (calcium, magnesium, sodium, potassium, etc.) that the cells need and reinject them into the bloodstream.
3 – Maintenance of Minerals Needed by the Body
Among them, we can mention the sodium and potassium that come from food. Their lack or excess can be the cause of severe complications … The kidneys, therefore, ensure their maintenance at a constant level, the surplus being eliminated in the urine.
4 – Maintenance of Acid-Base Balance in the Blood
Excess acids from the diet are removed to maintain the ideal blood composition (“neutral” blood PH).
5 – Production of Hormones, Enzymes, and Vitamins
In addition to their regulator and filter role, the kidneys also produce several hormones, enzymes, and vitamins including:
– Renin and angiotensin, essential for the regulation of blood pressure.
– Erythropoietin (the famous EPO) that acts on the bone marrow to produce red blood cells in sufficient quantity to carry oxygen in the body.
– Calcitriol, the active form of vitamin D, which allows the absorption of calcium by the intestine and its fixation in the bones, to ensure their good condition and robustness.
6 – The Kidneys Eliminate Organic Waste
The renal artery transports blood into the kidney. It then passes into the glomeruli, balls of small blood vessels whose wall serves as a filter. Each kidney has one million.
Purified, the blood comes out through the renal vein. Organic residues (water and salt in excess, urea …) are removed in the form of urine (between 1.5 and 2 l / day) via the ureters and the bladder.
*** A Foolproof Discretion
Even when they are not functioning properly, the kidneys hardly ever suffer, except in special cases (pyelonephritis, renal colic). Kidney disease is most often without specific symptoms until a very advanced stage. Hence the importance of regular screening (a urine test to check the presence of protein in small quantities) to identify a possible renal failure which, if it is taken in time, can be slowed down and may avoid dialysis. Depending on the results of analyzes, a visit to the nephrologist can start a suitable care device.
*** What Are the Risks If the Kidneys Work Poorly?
When the kidneys are suffering, collateral damage in the body can be significant.
– High blood pressure: the kidneys control water and salt in the body.
– A dysfunction causes an increase in arterial pressure.
– Anemia: if the kidneys do not produce enough EPO, the rate of red blood cells drops.
– Cardiovascular diseases: as soon as kidney function falls to 30% of its capacity, the risk of heart attack and stroke increases dramatically.
– An overdose of drugs: if the kidneys no longer perform their role of filtration, the blood concentration in an active molecule can rise dangerously.
– Osteoporosis: When vitamin D is not properly synthesized by the kidneys, the body no longer has enough calcium to protect the bones.
III – The Different Types of Kidney Diseases
Different routes, same destination: Many different types of kidney diseases cause the irreversible destruction of the kidneys, leading to chronic renal failure.
1 – Glomerular Diseases
They affect the glomerulus. Their cause is still not known with certainty but bacterial infections seem to be risk factors. They are called “primitive”. Glomerulonephritis can be categorized in many subgroups, not having the same rate of evolution ranging from 2 to 30 years. Renal biopsy can be used to diagnose it.
– Glomerular damage related to general diseases
They are the cause of 20% of kidney failure. The most common cause is diabetes, whether insulin-dependent or not. It can cause, after several years of evolution, diffuse lesions of small vessels in the eye, heart, and kidneys. This diabetic glomerulopathy progresses to end-stage chronic renal failure.
2 – Chronic Interstitial Nephropathies
They constitute 30% of chronic renal insufficiency and are characterized by lesions of the interstitial tissue.
– Pyelonephritis is due to very frequent urinary infections, especially in women. The bacterium in question is in 85% of the cases an Escherichia Coli, Coli bacteria originating from the intestinal flora. Generally not serious, they are localized at the level of the bladder. But if the bacterium reaches the urinary tract that is empty, either because of an obstacle (calculus, narrowing, large prostate), or because of functional discomfort (vesico-ureteral reflux, malformation), it multiplies and goes back into the kidney. It is the repetition of these kidney infections, or pyelonephritis, that causes inflammation of the interstitial tissue of the kidney. The progression to end-stage renal failure is slow (10 to 40 years). It can be delayed or avoided by surgical treatment associated with antibiotic treatment that fights the infection. Prevention requires a biological examination at the first signs of urinary infection (cystitis = burning and pain during urination).
– Chemical poisoning can be professional or drug (nephrotoxic).
3 – Vascular Diseases (Nephroangiosclerosis)
These diseases are due to high blood pressure (hypertension). HTA affects 10% of the population. In 90% of cases, it occurs without a specific cause and is called “essential”, however it can be a consequence of kidney disease. If left untreated, it damages the lining of the vessels, especially the heart, brain, and kidneys after several years. It then causes chronic renal failure. This nephroangiosclerosis accounts for at least 10% of chronic renal failure in elderly patients. If the HTA is well treated, we can stop this evolution.
4 – Congenital and Hereditary Diseases
– Polycystic disease (polycystic) is the most common: 8% of chronic renal failure is due to this disease, characterized by the development of numerous cysts in both kidneys. It is an inherited disease that affects both sexes. The risk of transmission differs according to the genetic form. It can evolve into adulthood towards chronic renal failure but in a very slow way. A number of polycystoses never reach the stage of chronic end-stage renal failure.
– Alport Syndrome is a hereditary disease characterized by abnormalities in the biochemical composition of the basement membrane of the glomerulus leading to a defect in the filtration. The association of auditory and even ocular and renal insufficiency, especially in boys, must be reminiscent of this disease.
IV – What to Do to Preserve Our Kidneys?
Kidney health is no exception to this golden rule of prevention: having a healthy lifestyle. Including a healthy diet: what you eat has an effect on the kidneys, one of whose functions is to eliminate waste. You are also told how to protect them if you take certain medicines that impair kidney function.
Did you know? From the age of 40, renal filtration begins to decrease by about 1% per year. In the long term, the risk is to develop kidney disease, all the more insidious as it evolves silently. In the stage of kidney failure, the personalized advice of a dietician is needed. But before reaching this point, some points deserve special attention.
1 – At the Salt Level
Eating too salty promotes high blood pressure and some forms of kidney stones. However, the French population has an average consumption of too much salt (about 8 to 9 g per day). A maximum of 6 to 7 g per day would be better for kidney health. To enhance the taste of the dishes, you can easily replace the salt with spices or herbs.
Namely: 1 g of salt is 60 g of cooked ham or 60 to 80 g of bread or 200 g of canned vegetables.
2 – At the Calcium Level
Calcium helps regulate blood pressure. It is therefore essential, even in people prone to calcium kidney stones. The recommended intakes are 900 milligrams a day. The only precaution to take is to distribute your calcium intake throughout the day.
Namely: 150 mg of calcium correspond to 1 glass (150 ml) of semi-skimmed milk or 1 yogurt (125 g).
Fruits and vegetables at every meal provide 200 to 300 mg of calcium a day. Tap water contains on average 100 mg of calcium per liter. The mineral waters Contrexéville, Hépar or Courmayeur contain 500 to 600 mg of calcium per liter.
3 – At the Protein Level
To avoid overloading the kidneys, while ensuring the needs of the body, we must absorb every day the equivalent of 1 g protein/kg ideal weight. For example, a 70-kilogram, non-underweight kidney woman, who should weigh 55 kilos, needs about 55 grams of protein per day.
“Animal proteins provide the amino acids needed by the body. In vegetable proteins, we must combine cereals and pulses to find all these basic elements, “says Marie-Paule Dousseaux, dietician-nutritionist. For the body to assimilate without increasing the work of the kidneys, it is better to split the protein intake during the three meals of the day.
Namely: 5 g of animal protein correspond to 150 ml of milk or 1 yogurt of 125 g or 25 g of meat/fish. 5 g of animal protein corresponds to 70 g of bread or 50 g of cooked lentils or 100 g of cooked pasta.
4 – Drink Enough Water
The body needs 1.5 liters of water a day, on average. In general, there is no need to go beyond this recommendation except in case of high heat, sweating or diarrhea. Another exception is that people who have a tendency to have urinary tract infections or kidney stones need to dilute their urine more, and to do so, drink about 2 liters a day. In this volume, we include not only water but also tea, coffee, infusions, and all liquids provided they are without salt or added sugar.
*** How to Protect Your Kidneys When Taking Medication?
The kidneys can be intoxicated by molecules present in all the medicine cabinets.
– Anti-inflammatories: these drugs are commonly prescribed as painkillers (osteoarthritis, menstruation, migraine …) Ibuprofen is even available over the counter in a pharmacy. Taken for several weeks, they put the kidneys in overpressure. They are contraindicated in case of renal insufficiency. “If your kidney function is normal, you’re not diabetic or hypertensive and you’re not over 70, you can take it easy, as long as it’s a cure.” short of a few days, “says Professor Isnard-Bagnis.
– Antacids: proton pump inhibitors (PPIs) are widely prescribed for heartburn. They often accompany taking anti-inflammatories. However, studies have shown that people taking long-term PPIs have poorer kidney function than others. “When prescribing them, you always have to ask yourself if they are really necessary,” says Corinne Isnard-Bagnis nephrologist at the Pitié-Salpêtrière Hospital (Paris). However, according to the CKD-REIN study coordinated by Bénédicte Stengel, an epidemiologist at Inserm, 30% of chronic renal patients take this type of medication.
Organ forgotten and poorly known, the kidney nevertheless performs functions essential to the good biological balance of the human body. We are almost all born with two kidneys. Some people may have only one. Their main role? Regulate the human body by eliminating waste produced by the body and transported by blood. It sometimes happens that one of the two kidneys falls ill without being noticed because the other takes over. A disease (pyelonephritis, renal calculus, kidney failure) can indeed affect the kidney and prevent it from fulfilling its role of a filter. Even serious, kidney disease can develop long without causing symptoms. The creatinine level, determined during a blood test, ensures that the kidney is functioning normally.
There are different types of kidney diseases or the urinary system: prostate cancer, kidney failure, cystitis or urinary incontinence…
Did you know? The five liters of blood in our body is spent 36 times a day in the kidneys.