Question

Question 10 List 4 (Four) processes that occur in the formation of urine (1.5 X 4 = 6 points). T T T Arial 3 (12pt) - T-

Answer 1

The answer is Filtration,Reabsorption,secretion
These are the major steps but to be precise,there are 4
-Glomerulus filters water and other substances from bloodstream,filteration membrane keeps large proteins and blood cells in blood stream,reabsorption moves nutrients and blood to bloodstream,waste ions and hydrogen ions secreted from blood complete urine formation
Initially filreration occurs where,glomerulus is the site of filtration.When blood passes through glomerulus,a plasma like filtrate obtained which is then captured by Bowman's capsule and then,they get funneled to renal tubule.This step marks the beginning of urine formation.
Fluid in glomerular capillaries pass through a layer called filtration membrane,which allows only smaller particles to pass through and blocks larger proteins marking the second step

In reabsorption,as the filtrate moves through nephron,the cells lining tubule will take up substances from the filtrate and pass to blood stream.These include sodium,chloride,bicarbonate,amino acid,glucose etc.The cells can take up these for energy,when the filtrate passed through Proximal tubule,99%amino acids ,glucose and water is reabsorbed.The portion not reabsorbed gets to form urine in the collecting duct.

Secretion of ions which make up urine -During tubular secretion,unfiltered particles pass from peritubular capillaries into lumen of tubule.The substances that are hard to filtrate pass from blood to tubule,ex-toxins,antibiotics.These then are excreted through urine.The secreted ions and filtrate makes up urine which is passed from tubule to collecting duct and excreted through renal pelvis,ureters etc