Excretory Products and their Elimination — BIOLOGY STD 11 Science — Question

Micturition the process of release of urine from urinary bladder is called micturition. A signal is initiated by the stretching of the urinary bladder as it gets filled with urine. In response, the stretch receptors on the walls of the bladder send signals to the CNS. The CNS passes on motor messages to initiate the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine.Disorders of excretory system:

1. Uremia: Accumulation of urea in blood is called uremia. Malfunctioning of kidneys can lead to uremia, which is highly harmful and may lead to kidney failure.
2. Renal calculi: Stone or insoluble mass of crystallized salts formed within the kidney are called renal calculi. They are commonly composed of calcium oxalate. They can cause pain if they cause obstruction and prevent urine flow in the ureter or kidney, or by direct irritation of the bladder.
3. Glomerulonephritis: It is inflammation of glomeruli of kidney. can be represented in a diagram as follows. Arrows indicate direction of movement of materials. Proximal convoluted tubule distal convoluted tubule.