Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Kidneys are bean-shaped organs located in the back of the abdominal cavity that filter blood to remove waste and excess fluids, forming urine. They also help maintain electrolyte balance and regulate blood pressure.
5 Must Know Facts For Your Next Test
The kidneys receive about 20% of the heart's output with each heartbeat.
Nephrons are the functional units of the kidneys, with each kidney containing about a million nephrons.
Kidneys produce erythropoietin, a hormone that stimulates red blood cell production in bone marrow.
The renal cortex is the outer part of the kidney where filtration occurs; the renal medulla is the inner part where urine collects before going to the bladder.
Normal microbiota in the urogenital tract can include non-pathogenic bacteria such as Lactobacillus species.
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Related terms
Nephron: The basic structural and functional unit of the kidney responsible for filtering blood.
Ureter: A muscular tube that carries urine from each kidney to the urinary bladder.