Table of ContentsView AllTable of ContentsAnatomyFunctionAssociated ConditionsTestsTreatment
Table of ContentsView All
View All
Table of Contents
Anatomy
Function
Associated Conditions
Tests
Treatment
The kidneys are the body’s filtration system. These fist-sized, bean-shaped organs manage the body’s fluid and electrolyte balance, filter blood, remove waste, and regulate certain hormones. They produce urine to carry the wastes out of the body.
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Each person has two kidneys. The kidneys are located on either side of the spine, with the top of each kidney beginning around the 11th or 12th rib space. The kidneys are sandwiched between the diaphragm and the intestines, closer to the back side of the abdomen.
Roughly the size of a closed fist, each kidney measures about 10 to 12 centimeters long, 5 to 7 centimeters wide, and 3 to 5 centimeters thick.
Each kidney is connected to the bladder through a ureter. The ureter brings waste products—urine—to the bladder, where it is stored until it leaves the body through the urethra. Together, all of these organs make up the renal system.
Structure
Each kidney is covered in a thick layer of connective tissue and fat that helps shape and protect the organ.
Arteries,renal veins, and nerves serve the kidneys. About 20% of the body’s cardiac output—or the amount of blood the heart pumps each minute—flows through the kidneys when the body is at rest.
Blood flows into the kidneys through renal arteries that originate at the aorta. As the blood passes through the kidneys, the vessels that carry the blood get smaller and smaller until they deliver blood to the nephrons, which are the functional units of the kidney.
Each kidney contains about 1.3 million nephrons, which do the filtering work of the kidneys. Within each nephron, there is a microscopic filtration unit consisting of an exterior capsule—Bowman’s capsule—and a network of tiny capillaries called glomerulus.
While in the tubules, liquid and solutes will diffuse through additional layers of filtration. Some liquids and solutes will be reabsorbed and returned to the body via the renal veins to the vena cava, while others will be secreted as waste—urine—through the ureters. The ureters transport urine to the bladder for storage until it is excreted from the body through the urethra.
Anatomical Variations
In some cases, the kidneys do not form correctly during pregnancy, resulting in congenital malformations.
The main purpose of the kidneys is to filter blood and maintain fluid and electrolyte balance in the body. Together, your kidneys filter your body’s entire blood volume about 300 times per day.Electrolytes and solutes likesodiumand potassium are regulated in the kidneys and transported to different parts of the body.
Blood is filtered several times while in the kidneys, returning about 99% of the water in your blood back into the circulation system, and turning the remaining water and any waste products into urine.
In addition to filtering blood and removing waste, one of the vital functions of the kidney is maintaining the body’s fluid volume. Electrolytes like sodium play a role in this process, as well as hormones like antidiuretic hormone (ADH), aldosterone, and atrial natriuretic hormone.
Electrolytes and hormones respond to the body’s needs to increase or decrease fluid volume, maintaining blood pressure and the body’s overall homeostasis.
9 Ways to Keep Your Kidneys Healthy
A number ofdiseasesand conditions can impact the function of the kidneys. Some are genetic and others develop as a result of other diseases or lifestyle choices.
There are a number of blood tests, urine tests, and scans that can help a doctor determine how well your kidneys are functioning.
In cases of severe kidney damage and loss of function, the body can no longer maintain its fluid and electrolyte balance. Toxic levels of waste can cause neurologic and/or cardiac problems.
You can work to prevent risk factors for kidney disease like type 2 diabetes and high blood pressure and to control them if you have these conditions.
Kidney failurewill require more intensive treatment. Treatments can include medications or, in severe cases, dialysis. Dialysis uses an external process to filter blood in place of your kidneys. Dialysis is usually used until a kidney transplant is possible.
Kidneys can be transplantedfrom living or deceased donors. Diseased kidneys are sometimes left in place during transplantation, but may be removed in some cases. The new kidney—often from a close family member in the case of a living donor—is then implanted and connected to your blood vessels and bladder. There are a host of standard surgical risks involved, as well as the chance that your body may reject the new organ.
If one kidney fails, is donated, or issurgically removed to treat cancer or other conditions, it ispossible to survive with only one kidney, but there are risks, and regular testing is required.
12 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Soriano RM, Leslie SW.Anatomy, abdomen and pelvis, kidneys. StatPearls.Johns Hopkins Medicine.Anatomy of the urinary system.Biga LM, et al.Internal and external anatomy of the kidney.OpenStax/Oregon State University.Anatomy and Physiology.Mullens W, Nijst P.Cardiac output and Renal dysfunction: Definitely more than impaired flow.J Am Coll Cardiol. 2016;67(19):2209-2212. doi:10.1016/j.jacc.2016.03.537Rabinowitz R, Cubillos J.Kidney Defects. Merck Manual.Biga LM, et al.Physiology of urine formation.OpenStax/Oregon State University.Anatomy and Physiology.Cleveland Clinic.Kidney disease: Chronic kidney disease.Gounden V, Jialal, I.Renal function tests. StatPearls.National Kidney Foundation.Estimated glomerular filtration rate.Johns Hopkins Medicine.Kidney ultrasound.Cleveland Clinic.Kidney transplant procedure.National Kidney Foundation.Living with one kidney.
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Soriano RM, Leslie SW.Anatomy, abdomen and pelvis, kidneys. StatPearls.Johns Hopkins Medicine.Anatomy of the urinary system.Biga LM, et al.Internal and external anatomy of the kidney.OpenStax/Oregon State University.Anatomy and Physiology.Mullens W, Nijst P.Cardiac output and Renal dysfunction: Definitely more than impaired flow.J Am Coll Cardiol. 2016;67(19):2209-2212. doi:10.1016/j.jacc.2016.03.537Rabinowitz R, Cubillos J.Kidney Defects. Merck Manual.Biga LM, et al.Physiology of urine formation.OpenStax/Oregon State University.Anatomy and Physiology.Cleveland Clinic.Kidney disease: Chronic kidney disease.Gounden V, Jialal, I.Renal function tests. StatPearls.National Kidney Foundation.Estimated glomerular filtration rate.Johns Hopkins Medicine.Kidney ultrasound.Cleveland Clinic.Kidney transplant procedure.National Kidney Foundation.Living with one kidney.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Soriano RM, Leslie SW.Anatomy, abdomen and pelvis, kidneys. StatPearls.Johns Hopkins Medicine.Anatomy of the urinary system.Biga LM, et al.Internal and external anatomy of the kidney.OpenStax/Oregon State University.Anatomy and Physiology.Mullens W, Nijst P.Cardiac output and Renal dysfunction: Definitely more than impaired flow.J Am Coll Cardiol. 2016;67(19):2209-2212. doi:10.1016/j.jacc.2016.03.537Rabinowitz R, Cubillos J.Kidney Defects. Merck Manual.Biga LM, et al.Physiology of urine formation.OpenStax/Oregon State University.Anatomy and Physiology.Cleveland Clinic.Kidney disease: Chronic kidney disease.Gounden V, Jialal, I.Renal function tests. StatPearls.National Kidney Foundation.Estimated glomerular filtration rate.Johns Hopkins Medicine.Kidney ultrasound.Cleveland Clinic.Kidney transplant procedure.National Kidney Foundation.Living with one kidney.
Soriano RM, Leslie SW.Anatomy, abdomen and pelvis, kidneys. StatPearls.
Johns Hopkins Medicine.Anatomy of the urinary system.
Biga LM, et al.Internal and external anatomy of the kidney.OpenStax/Oregon State University.Anatomy and Physiology.
Mullens W, Nijst P.Cardiac output and Renal dysfunction: Definitely more than impaired flow.J Am Coll Cardiol. 2016;67(19):2209-2212. doi:10.1016/j.jacc.2016.03.537
Rabinowitz R, Cubillos J.Kidney Defects. Merck Manual.
Biga LM, et al.Physiology of urine formation.OpenStax/Oregon State University.Anatomy and Physiology.
Cleveland Clinic.Kidney disease: Chronic kidney disease.
Gounden V, Jialal, I.Renal function tests. StatPearls.
National Kidney Foundation.Estimated glomerular filtration rate.
Johns Hopkins Medicine.Kidney ultrasound.
Cleveland Clinic.Kidney transplant procedure.
National Kidney Foundation.Living with one kidney.
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