Question

Define excretion and explain how urine is formed??

Answer 1

the process of removing waste generated in our body is called excretion

Answer 2

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⇒Excretion is the process of removal of metabolic wastes from the body.

⇒Excretion is the process in which undigested toxic and waste material is thrown out of the body .It can be in the form of sweat,urine etc .

How Urine is Formed ? :

• Urea is the main Nitrogenous Waste of human being which is formed in the liver.

• Then, the impure blood reaches the kidney through renal arteries and these renal arteries divide into several fine Afferent arterioles which gives the blood in Glomerulus situated in the Bowman’s Capsule.

• The size of afferent arterioles is larger than the diameter of efferent arterioles .

• Due to this and some other factors the blood pressure increases in capillaries of Glomerulus .This high blood Pressure leads to ultrafiltration of the blood of Glomerulus.

• Glomerulus is a network of capillaries filtering the blood and passes it to the Bowman’s Capsule.

• Due to this ultrafiltration small substance like Glucose , amino acids and some other organic substance and water filtered out and reach Bowman’s Capsule.

• Bowman’s Capsule through these filtering blood reach into PCT {Proximal Convoluated Tube}

• In PCT , the filtration of blood takes place again and absorbs glucose , amino acids , salts and other important substance from the filtrate and pass into the Loop of henle’s .Reabsorption takes place in two ways : back diffusion and Active transport.

• In loop of henle’s concentrated urine formation occurs which passes to the DCT .In ascending limb of henle’s loop the remaining 25% of K + And some CT and Na + ions are actively reabsorbed.

• The DCT passes the concentrated urine Formation occurs which passes to the DCT .

• Then urethers pass the urine into urinary bladder for stored then urinary bladder in increase pressure then Urethra through urine excrete out from the body .