The urinary system, or renal system, has four main components — the kidneys, ureters, urinary bladder, and urethra. The kidneys are a pair of ...

The kidneys are located at the T12 to L3 vertebrae and partly protected by the eleventh and twelfth ribs. A kidney typically measures about 10 to 12 cm in ...

In the frontal section, the kidney shows the renal cortex, renal medulla, and renal pelvis. The outermost layer — the renal cortex — is ...

The segmental arteries branch out, supplying different kidney regions. These segmental arteries branch off and pass through the renal columns as ...

A nephron is the functional unit of the kidney. It comprises two main parts — the renal corpuscle and renal tubule. The renal corpuscle, where blood ...

The renal corpuscle comprises a cluster of capillaries known as the glomerulus and the glomerular or Bowman's capsule that encloses the glomerulus. ...

The nephron measures approximately 3 cm and consists of the proximal convoluted tubule, loop of Henle, and distal convoluted tubule. The proximal ...

The formation of urine involves three steps —  glomerular filtration, tubular reabsorption, and tubular secretion. Glomerular filtration occurs ...

During glomerular filtration, blood plasma is pushed through the pores of a filtration membrane. The glomerular capillaries and podocytes together form ...

Glomerular filtration depends on three main pressures: glomerular blood hydrostatic pressure or GBHP, capsular hydrostatic pressure or CHP, and blood ...

The glomerular filtration rate or GFR is the volume of filtrate formed per minute by the glomeruli. Any changes in the local blood pressure and flow can ...

Tubular reabsorption occurs along the length of the renal tubules and collecting ducts. This process returns water and solutes from the filtrate to the ...

The proximal convoluted tubules, or PCTs, reabsorb most filtered water, ions, glucose, and amino acids. Sodium ion transport is a critical process in the ...

The thick ascending limb of the nephron loop has Na+–K+–2Cl− symporters in the apical membranes of its cells. These symporters ...

The early part of the distal convoluted tube, or DCT, reabsorbs around 10 to 15% of the filtered water and 5% of the filtered sodium and chloride ions. ...

Urine is mostly water, which makes up around 95% of its volume. The remaining 5% consists of different solutes. Urea, a byproduct of amino acid breakdown, ...

The kidney's juxtamedullary nephrons produce dilute urine when the fluid intake is high. In the renal cortex, the osmolarity of the interstitial fluid ...

There is a medullary osmotic gradient of solutes in the interstitial fluid from the renal cortex through the medulla. This gradient is established and ...

The glomerular filtration rate is an effective metric for assessing kidney function. One way of measuring GFR is by calculating renal clearance. Renal ...

Ureters are retroperitoneal tubes on either side of the vertebral column that transport urine from each kidney to the urinary bladder. They have thick ...

The urinary bladder is a hollow, muscular sac that temporarily stores about 600 mL of urine before micturition.  It is retroperitoneally situated on ...

Micturition or urination primarily involves coordination between the bladder detrusor muscle and two sphincters to control bladder emptying. It is ...

The urethra is a tube-like structure extending from the lower end of the urinary bladder to the external opening for releasing urine out of the body. In ...

Renal failure is classified as acute when the glomerular filtration rate or GFR suddenly drops below 15 mL/min or ceases entirely. In contrast, a gradual ...

Urinary system disorders can arise from infections, stress, age, congenital abnormalities, and lifestyle. Urinary tract infections are typically caused by ...