Question

B. 19. The flow of urine through our Urogenital Tract is as follows: A. Ureters → Kidneys → Urethra → Bladder Ureters → Urethra → Bladder → Kidneys Kidneys → Ureters → Bladder → Urethra Kidneys → Urethra → Bladder → Ureter E. Kidneys → Bladder → Ureters → Urethra

Answer 1

The correct answer is Option C

Kidneys -> Ureters -> Bladder -> Urethra

Urine formation occurs in the kidneys. It involves three processes: glomerular filtration, tubular reabsorption and tubular secretion. • Glomerular filtration: Walls of glomerular capillaries and Bowman's capsule are very thin and are semipermeable due to the presence of pores in the former and slit pores in the latter. They allow water and small molecules in the blood to pass through them. Fluid containing these materials is forced out of the glomerular capillaries into the Bowman's capsule by the high pressure of the blood in the glomerular capillaries. Tubular reabsorption: From the Bowman's capsule, the glomerular filtrate passes into the tubule and flows through it to the collecting duct. During this course, its composition, osmotic pressure, and pH change due to selective reabsorption of materials from it and secretion of more waste materials into it. It consists of proximal convoluted tubule (PCT), Henle's Loop and distal convoluted tubule (DCT). Tubular secretion: Creatinine, hippuric acid are actively secreted into the filtrate in the PCT from interstitial fluid. Hydrogen ions and ammonia are also secreted into the PCT. Potassium, hydrogen, bicarbonate ions are secreted by active transport, into the filtrate in the DCT. Urea enters the filtrate by diffusion in the thin region of the ascending limb of Henle's loop.

The glomerular filtrate reaching the end of the collecting duct is called final urine. Urine is produced and drained continuously by the nephrons into the renal pelvis. From here, it is carried down the ureters by peristaltic waves into trigonum vesicae and thence into the body of the urinary bladder. As urine collects, the muscular walls of the bladder distend to accommodate it. During the discharge of the urine, the bladder and urethral sphincters relax and the smooth muscles of the bladder wall gradually contract. This slowly drives the urine from the bladder through the urethra to the exterior.

G D * KIDNEY H URETER > URINARY BLADDER → URETHRA