Kidneys are vital organs found in both vertebrates and invertebrates. They play a crucial role in maintaining the body’s internal balance and overall health. In humans, the kidneys are a pair of reddish, bean-shaped organs located on either side of the spine, just below the rib cage. These organs perform several critical functions, including filtering blood, regulating body fluids, and maintaining the right levels of electrolytes in the body.
This article explores the structure, functions, and importance of kidneys, as well as kidney-related diseases and treatments.
The kidneys are a pair of bean-shaped organs approximately 5 inches long, about the size of a fist. They are located in the retroperitoneal area, one on each side of the spine. In adults, the kidneys weigh between 125 to 175 grams in males and 115 to 155 grams in females.
The primary role of the kidneys is to filter blood, remove waste products, and regulate fluid and electrolyte balance. They also convert waste into urine, which is then excreted from the body through the ureter. All the blood in the body passes through the kidneys multiple times a day for filtration, making these organs essential for sustaining life.
The kidneys are located in the retroperitoneal cavity behind the abdominal organs. Their structure is asymmetrical due to the position of the liver. The right kidney is slightly smaller and positioned lower than the left kidney to accommodate the liver. Each kidney is surrounded by a strong, fibrous renal capsule and two layers of fat:
Above each kidney lies an adrenal gland, which plays a role in hormone production. The kidneys are protected by the 11th and 12th ribs, ensuring their safety from physical damage.
A kidney has a concave and convex edge. The concave part contains the renal hilum, an area where blood vessels, nerves, and the ureter connect to the kidney. Internally, the kidney is divided into three parts:
The kidneys are multifunctional organs that contribute to maintaining homeostasis in the body. Here are their primary functions:
One of the main functions of the kidneys is filtering blood. Every day, approximately 50 gallons of blood pass through the kidneys. The filtration process occurs in the glomerulus, a cluster of tiny blood vessels in the nephron (the functional unit of the kidney).
During filtration:
The kidneys regulate the body’s fluid levels and maintain a balance of electrolytes, such as sodium, potassium, and calcium. This function ensures proper hydration and prevents dehydration or electrolyte imbalances.
The kidneys help maintain the body’s pH level between 7.38 and 7.42. They do this by:
This process prevents the body from becoming too acidic (acidosis) or too alkaline (alkalosis).
Osmolality refers to the balance between water and electrolytes in the body. The kidneys regulate osmolality by releasing antidiuretic hormone (ADH) from the pituitary gland. ADH increases water reabsorption in the kidneys, maintaining hydration and proper mineral balance.
The kidneys play a role in regulating blood pressure by:
The kidneys produce and regulate several important hormones:
The kidneys excrete waste products like urea (a byproduct of protein metabolism) and uric acid (produced from nucleic acid breakdown). These substances are removed from the body through urine.
Each kidney contains approximately one million nephrons. Nephrons are the basic structural and functional units of the kidneys. They perform filtration, reabsorption, and secretion. A nephron consists of:
The number of nephrons varies across species. For example, a human kidney has about one million nephrons, while a mouse kidney has only around 12,500.
CKD occurs when the kidneys gradually lose their ability to function. It can be caused by diabetes, high blood pressure, or other underlying conditions. Treatment includes medication, lifestyle changes, and, in severe cases, dialysis or kidney transplantation.
Kidney stones are hard deposits of minerals and salts that form in the kidneys. They cause pain and difficulty in urination. Treatments include medication, hydration, or surgical removal.
This condition damages the glomeruli, leading to protein loss in the urine. Treatment involves managing symptoms with medication and addressing the underlying cause.
AKI is a sudden loss of kidney function, often caused by dehydration, infections, or medications. Treatment focuses on addressing the cause and restoring kidney function.
This is a bacterial infection of the kidneys that requires antibiotics and, in severe cases, hospitalization.
When both kidneys fail, a kidney transplant becomes a life-saving option. During this procedure, a healthy kidney from a donor is implanted into the patient’s body. Post-transplant care includes medications to prevent organ rejection and regular check-ups to monitor kidney function.
Renal physiology is the study of kidney functions, while nephrology is a specialized branch of medicine that deals with kidney-related diseases. Nephrologists diagnose and treat conditions like CKD, nephrotic syndrome, and kidney infections.
Maintaining healthy kidneys is essential for overall well-being. Here are some tips to protect your kidneys:
The kidneys are indispensable organs that perform several life-sustaining functions. Understanding their structure, functions, and importance can help us take better care of these vital organs and maintain a healthy life.
You can see blood in your urine and you also have foam. You will have trouble concentrating and you will experience swelling and dryness on your skin.
It is not possible to live without the kidneys. But since we have two, it is possible to live with one kidney.
People with diseases such as diabetes and high blood pressure are more likely to have kidney problems.