renal system
Quick Summary
The renal system in humans is an organ system responsible for producing urine and eliminating waste. It includes the kidneys, where urine is formed, and the ureters, bladder, and urethra, which transport, store, and expel urine. The kidneys play a vital role in maintaining the body's internal balance by filtering blood, removing dissolved waste products, and regulating electrolyte composition.12
Each kidney contains about one million nephrons, the functional units responsible for urine production. Within the nephron, fluid filters from the blood in the glomerulus into a tubule. As this filtrate moves through the tubule, essential substances are reabsorbed into the blood, and waste products are secreted into the filtrate, ultimately forming urine. The kidneys also perform nonexcretory functions, such as secreting hormones like renin and erythropoietin. Urine travels from the kidneys through the ureters to the bladder for storage before being eliminated through the urethra.3214
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animal developmentExcretory organsThe kidneys of vertebrates consist of a mass of tubules that develop from the stalks of somites called nephrotomes. In some primitive vertebrates such as cyclostomes, the nephrotome in each segment gives rise to only one tubule, but, in the great majority of…
Read MoreThe kidneys of vertebrates consist of a mass of tubules that develop from the stalks of somites called nephrotomes. In some primitive vertebrates such as cyclostomes, the nephrotome in each segment gives rise to only one tubule, but, in the great majority of…
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prenatal developmentUrinary systemVertebrates have made three experiments in kidney production: the pronephros, or earliest type; the mesonephros, or intermediate kidney; and the metanephros, or permanent kidney. All arise from the cellular plates called
Read MoreVertebrates have made three experiments in kidney production: the pronephros, or earliest type; the mesonephros, or intermediate kidney; and the metanephros, or permanent kidney. All arise from the cellular plates called
Read More