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Chapter 29

Chapter 29

The Urinary System

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 …
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 …
Glomerular filtration depends on three main pressures: glomerular blood hydrostatic pressure or GBHP, capsular hydrostatic pressure or CHP, and blood …
Nephron endowment refers to the total number of nephrons an individual is born with, as nephrogenesis in humans is completed by 36 weeks of gestation and …
Transdermal measurement of glomerular filtration rate (GFR) has been used to evaluate kidney function in conscious animals. This technique is well …
A range of conditions involving the kidneys and urinary bladder can cause organ-threatening complications that are preventable if diagnosed promptly with …