The kidneys

kidneysYour kidneys are two bean-shaped organs located on either side of your abdominal cavity.

The kidney on your left side is usually just a bit higher up, due to the liver’s placement, and is also a little larger. It is generally 11-14 cm long, 6 cm wide and 4 cm thick.

The kidneys handle three major functions: release of hormones, gluconeogenesis and extracellular homeostasis of blood and pH components. Let’s look at each one individually.

Release of hormones

Hormones released by the kidneys are erythropoietin, rennin and calcitriol and prostaglandins. Erythropoietin regulates red blood cell production in your bone marrow. Renin is a necessary component of the renin-angiotensin system, which regulates your blood pressure and water balance. When your blood volume is low, juxtaglomerular cells in your kidneys inject rennin into blood circulation. This will begin the process that causes the tubules in your kidneys to increase the reabsoprtion of both sodium and water into the blood. Doing so increases the amount of fluid on your body, which consequently increases blood pressure.

If the renin-angiotensin system is overactive, the result will be high blood pressure. The kidneys release an active form of Vitamin D (called calcitriol) which increases the level of calcium in the blood by upping the amount of calcium absorbed from the gut into the blood and possibly by increasing the secretion of calcium into blood from bones. Lastly, the kidneys release prostaglandins, a group of lipid compounds derived from fatty acids.


During gluconeogenesis, the kidneys produce glucose from lactate, glycerol and glutamine. This production is regulated by insulin, catecholamines and hormones in the kidneys.


Lastly, the kidneys maintain homeostasis in the body by regulating a number of substances. They include glucose (glucose not reabsorbed by the kidney appears in urine, an ailment known as glycosuria, which can cause dehydration), oligopeptides, proteins, amino acids, sodium, urea, water, chloride, bicarbonate, potassium, protons, magnesium, calcium, carboxylate and phosphate.

By regulating these substances, your kidneys help maintain the balance your body needs to operate properly. Without this regulation, the body would fall out of its acceptable pH levels. When this happens, proteins are denatured, enzymes are unable to function and the body will cease being able to sustain itself. Kidneys avoid this by balancing the amount of acids and bases in blood plasma. The process of maintaining what is called acid-base homeostasis is renal excretion.

Renal excretion is made up of three different functions: filtration, reabsoprtion and secretion. Let’s look at each individually.


Filtration is simply what happens as blood flows through the kidneys. A difference in blood pressure that occurs between two different parts of the kidneys causes small molecules like glucose, amino acids, urea, sodium chloride and water to go through a filter. These mechanics can also be used in hemodialysis, which cleans your blood while keeping it intact.

During excretion, the kidneys essentially select a myriad of waste products that your body’s metabolism produces and creates urine with them. It is actually a very involved and complicated system that involves your kidneys calculating what is to be selected as waste, how much of it will be excreted, etc.


Finally, the kidneys handle reabsorption of essential nutrients. This reabsorption helps maintain levels of glucose, amino acids, bicarbonate, Cl-phosphate, water, potassium, magnesium and sodium amongst others.

Renal failure

Obviously, the kidneys are an important part of the body’s mechanics, so if they become compromised, it is to great detriment. Called “renal failure”, when kidneys cease to function properly, the body’s health is at risk immediately.

Renal failure can be caused by acute kidney injury or chronic kidney disease. The former is generally reversible, while the latter usually isn’t. Problems may include increase bodily fluid which can lead to swelling, an increase in acidity in the body, higher than normal levels of potassium, lower than normal levels of calcium, increased phosphate and even anemia.

Symptoms can be unique by person, but they will generally include an effect on urination. This can be a change in the amount of urinating, the color of the urine (including if there’s blood) and difficulty or pain when urinating. Because the kidneys are responsible for the regulation of so many different chemicals, the symptoms that occur will depend on which chemicals are no longer being regulated correctly. If it’s potassium for example, the victim may experience abnormal heart beats or paralysis of their muscles. If it’s phosphates that are not being filtered, someone can experience bone damage and muscle cramps.

Acute kidney injury occurs when a damage to the body results in an interruption of blood supply to the kidneys or when the kidneys themselves become overloaded with toxins. A number of different injuries can have this effect, but so can complications from a surgery, drug overdoses or the result of too many pharmaceutical drugs taken with good intent. Another cause can be a ‘crush syndrome’ when great volumes of toxins are suddenly released into the blood circulation after a limb that which was formerly compressed is suddenly freed, allowing the toxins to begin circulating again.

Chronic kidney disease is generally caused by hypertension, diabetes or what’s called polycystic kidney disease. These generally all have genetic roots.

Given how important they are to the body, and how much damage can be done if they are not well looked after, you should be aware of the steps you can take to keep your kidneys in optimal health. There are a number of foods which do a great job of maintaining your kidney’s health.

To provide your kidneys with the vitamins, healthy fats and protein they need make sure your diet includes a number of the following foods: red bell peppers, garlic, cabbage, cauliflower, olive oil, egg whites, apples, onions, cranberries, raspberries, strawberries, blueberries, cherries, red grapes and fish. Further steps you can take to care for your kidneys are getting regular exercise, keeping your weight down, getting an annual physical, learning your family’s medical history, monitor your cholesterol and blood pressure and abstain from smoking and abusing alcohol.

Your kidneys may not take up a lot of space in the body, but that doesn’t make them any less important. Without your kidneys, your blood couldn’t get clean and the balance of chemicals in your body would be thrown off with dire effects. Be sure to get annual checkups where your doctor monitors for any kidney problems and take care to include the aforementioned kidney-friendly foods in your diet.

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