Question

2. Name and describe the three major processes used by the vertebrate kidney to achieve the final composition of the urine. Be sure to discuss the level and type of control for each of these processes (15 pts).

Answer 1

The kidney filter the unwanted substance from the blood and produced urine to excrete them. Three major process used by the vertebrate kidney to achieve the final composition of urine :

1. glomerular filtration

2 . Reabsorption

3 . secretion

These process ensure that only waste and excess water removed from the body.

● The glomerular filters water and other substance from the bloodstream. Each kidney contain 1 million nephrons.

●each nephrons has a glomerulus, the site of the blood filtration.

● the glomerulus is network of capillaries surround by a cup-like structure .as a blood flows through the glomerulus, blood pressure pushes water and solute from the capillaries into the capsule through a filtration membrane. This glomerulus filtration begins with the urine formation process.

●The filtration membrane keeps blood cells and large protein in the bloodstreams.

●The filtration membrane allows water and small solute to pass but block blood cells and large protein. Those components remain in the bloodstreams.

● The filtrate flows from the glomerular capsule further into the nephrons.

●Reabsorbtion moves nutrients and water back into the bloodstreams. Reabsorption is the second step of urine creation.

●the filtrate contain waste and other substance that body needs like essential ions, glucose, amino acid, smaller proteins.

● then this flitrate come into renal tubule.

●As it moves the needed substance and some water are reabsorbed through the tube wall into adjacent capillaries.

●waste ions and hydrogen ions secreted from the blood complete the formation of urine.

●waste ions and hydrogen ions are pass from the capillaries into the renal tubule, this process is called as secretion.

●the secreted ions are combine with the remaining flitrate and become a urine

●The urine flows out of the nephron tubule into the collecting duct. It passes out of kidney through the renal pelvis , into the ureter, and down to the bladder.

● Urine is 95%of water and 5%of waste.

●Nitrogenous waste excreted in urine include urea, creatinine, ammonia and uric acid.

●ions such as sodium , potassium, calcium are also excreted.