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Kidney

One of a pair of organs in the abdomen. The kidneys remove waste and extra water from the blood (as urine) and help keep chemicals (such as sodium, potassium, and calcium) balanced in the body. The kidneys also make hormones that help control blood pressure and stimulate bone marrow to make red blood cells.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

How Do the Kidneys Work?

A healthy person has two kidneys, which look like oversized beans. The kidneys are located to the right and left of the spine, just below your ribcage.

Your kidney is about as big as a bar of soap or the size of your fist. It weighs between 135 and 150 grams. The indented edge of the kidney is turned inward towards the spine. At the middle of this indentation a tube called the ureter leaves the kidney, and nerves, and blood and lymph vessels also lead in and out of the kidney. Each kidney is covered by three layers made out of fat or connective tissue, the so-called kidney capsule (or renal capsule). These layers give the kidney extra stability, protect it from external harm and anchor it in the surrounding tissue.

The kidney is surrounded by a thin outer renal cortex. There are about 2.4 million renal corpuscles in the renal cortex. These make urine. The renal medulla is found inside the... Read more about the Kidney

Terms to know

Adrenal Glands
A gland located on each kidney that secretes hormones regulating metabolism, sexual function, water balance, and stress.
Bladder
The organ that stores urine.
Blood
A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.
Body Fiber
In the body, fiber refers to tissue made of long threadlike cells, such as muscle fiber or nerve fiber.
Bone Marrow
The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.
Electrolytes
Chemicals in the body fluids that are parts of salts, including sodium, potassium, magnesium, and chloride. The kidneys control the amount of electrolytes in the body.
Erythrocytes (Red Blood Cells)
A cell that carries oxygen to all parts of the body.
Hormones
A messenger molecule that helps coordinate the actions of various tissues; made in one part of the body and transported, via the bloodstream, to tissues and organs elsewhere in the body.
Liver
The largest abdominal organ. The liver carries out many important functions, such as making important blood proteins and bile, changing food into energy, and cleaning alcohol and poisons from the blood.
Nephrologist
A doctor who treats people who have kidney problems or related conditions, such as hypertension.
Renal Pelvis
The area at the center of the kidney. Urine collects here and is funneled into the ureter, the tube that connects the kidney to the bladder.
Ureter
The tube that carries urine from the kidney to the bladder.
Urethra
The tube that carries urine from the bladder to the outside of the body.
Urinary Tract
The organs of the body that produce and discharge urine. These include the kidneys, ureters, bladder, and urethra.
Urine
Liquid waste product filtered from the blood by the kidneys, stored in the bladder, and expelled from the body by the act of urinating.

Terms to know

Adrenal Glands
A gland located on each kidney that secretes hormones regulating metabolism, sexual function, water balance,...
Bladder
The organ that stores urine....
Blood
A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called p...
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