Explain why :

(a) Skin functions as an accessory excretory organ.


The skin has sweat and sebaceous glands which excrere or eliminate certain substances along with their secretion. The sweat secreted by the  sweat glands contains salts, lactic acid, amino acid etc. Sebaceous glands secrete sebum to keep skin waterproof and hair greasy, but it contains some excretory products like waxes, sterols, fatty acids and some hydrocarbons.
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Write nitrogens waste products in different vertebrates.


Write nitrogens waste products in different vertebrates.
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Briefly explain the following:
i. Flame cells.
ii. Nephridia.

i. Flame cells - They are also known as protonephridia. These are the excretory structures found in platyhelminthes, rotifers and some annelids. They are primary concerned with ionic and fluid volume regulation. 

ii. Nephridia - are tubular excretory strauctures found in earthworms and other annelids. These help to remove the nitrogenous wastes and maintain fluid and ionic balance. 

 
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Discuss the various abnormal constituents of urine.

Abnormal constituents of urine are :

1. Proteinuria : e.g. When albumin and globulin are present in urine.

2. Glycosuria : When glucose is present in urea.

3. Hematuria : It is the presence of blood in urine is called hematuria.

4. Ketouria : The presence of ketone bodies causes ketouria.

5. Albuminuria : Presence of albumin in urine is callcd albuminureu.

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 Explain why :
(c) Micturition is reflex process but is under some  control.

Micturition is the process of release
of urine.
The neural mechanisms causing it is called the micturition reflex.
The stretching of the urinary bladder activates the stretch receptors on the walls of the bladder. These receptors send signals to the central nervous system. The CNS passes the motor message to initiate the contraction of smooth muscles of the bladde and simultaneous relaxation of the urethral sphincter causing the release of the urine. 
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