Where does the water goes which we drink?

 Excretory system 

The process of elimination of metabolic waste from the body is called excretion.

Removal of excess of water from the body or keep water  content constant is called osmoregulation.

Depending on the type of waste, nitrogen elimination is of three types .

1. Ammonotelism  is the elimination of nitrogen mainly in the form of ammonia example aquatic vertebrates Bony fishes and amphibians.
2. Ureotelism -is the removal of nitrogen mainly as urea. Ammonia combine with carbon dioxide in liver to form urea, Example mammals, men, frog, toads.
3. Uricotelism-is the elimination of nitrogen mainly as uric acid example bird, reptiles , many insects.

Uric acid is commonly  commercially extracted from bird dropping.

   Excretory organ of invertebrates

• Flame  cell are the organ of excretion in tapeworm.
• Sponges remove their waste through their water canal system. 
• In hydra, salary is waste into coelenteron.
• In annelids , excretion take place in nephridia.
• In insects, excretion takes place in Malphigian tubules .
• In some arthropods green glands also helps in excretion.
• Waste material in amoeba is taken out  by plasmaLamma.
• Spiders have coxal glands .

   Excretion system of humans

Excretory system of human consist of following organs

1. Kidney

• Kidney is paired  been shaped organ, that is present in abdomen just below the diaphragm.
• The left kidneys placed a little higher than the right kidney (reverse in rabbit).
• Concavity of kidney called hilus is always inverterly directed.
• They form urine and a drain it ultimately into pelvis of the kidney from where the ureters arises.
• Water reabsorption in kidney is a controlled by a hormone called ADH.
• In anuria, Guinness become unable to form urine.

     Nephron

It is a functional unit of kidney.

• In one kidney around 1 million nephron are found.

      It has two parts 

1. 1 Bowman's  capsule 

• It has network of blood capillaries called glomerulus, which together formMalpighian body.
• Blood enters glomerulus capillaries through different arteriole and leaves different arteriole.

      1.2   Renal tubule

     It consists of three parts

• Proximal convoluted tubule (pct).
• Loop of henle with thin descending and thick ascending limb.
• Digital convoluted tubule ( DCT ) which opens into collecting duct.

1. 2.1 skin excreats  mainly water and NaCl in sweats. Definition of sweat to require latent heat from the body due to with body feels cools . This is known as perspiration.

     1.2.2. Lungs excs create CO2 and some water vapour. Liver screates  bile pigment and cholesterol in the bile.

      

     2 .Ureters 

 This muscular tube  emerges  out from the hilum of kidneys. urine enters the ureter from the renal pelvis .

    3.Urinary bladder

 Sac- like structure which stores urine temporary. it is absent in birds .

   4.Urethra 

• Membraneous tube which conducted in to the exterior. urethral sphincters  keep the urethra closed accept during voiding  of urine.
• The act of voiding urine is called micturition.
• An adult man secretes 1-8 l of urine in 24 hours.
• The yellow colour of urine is due to the presence of pigment EuroChrome. ph of urine should be 5.8.
• When water and take is high ,the urine  is hypotonic.
• When there is less body water ,the rain is hypertonic.

      

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