Radial & Bilateral symmetry , Parazoa VS Eumetazoa

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Radial & Bilateral symmetry 

Parazoa VS Eumetazoa 

chapter #10 

Kingdom Animalia

Class 1st year biology

Diploblastic and triploblastic organisation | pseudocoelomate vs coelomate vs acoelomate

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Diploblastic and triploblastic organisation

Pseudocoelomate VS Coelomate VS Acoelomate

Chapter 10 Kingdom Animalia

Class 11 (F.Sc 1st year pre-medical)

excretion in animals

EXCRETION IN ANIMALS:

Keeping in view the definition of excretion, that it is the elimination of waste

metabolites several products may be included in the list of excretory products.

 Water:

Water may be considered as waste due to its removal in hypo osmotic (Internal) environment.             

Salts:

Salts removed by animals in hypertonic (External) environment are the excretory products for these animals, e.g. Marine cartilaginous fishes.

Nitrogenous Wastes:

Otherwise, overwhelmingly, nitrogenous waste metabolites constitute the excretory products.

Formation of Nitrogenous Waste:

Primarily, in the catabolism of animo-acids the amino group (---NH2) is released (deamination) or transferred to another molecule for removal or reuse.

 

Amino group not reused for recycling of amino acids is essentially dissolved in water and excreted to avoid toxic rise in the plasma. Elevated levels of these wastes can cause convulsions, coma and eventually death.

Major Nitrogenous Wates:

Mostly excess nitrogen is excreted by animals as

1.        Ammonia                                                                  

2.      Urea   

3.       Uric acid

 

Minor Excretory products:

Lower quantities of nitrogen are excreted in the form of other compounds such as creatinine, creatine or trimethylamine oxide

Trace Waste Products:

Some nitrogenous wastes are excreted in very small quantities such as

amino acids, purines and pyrimidines.

Metabolism of purine and pyrimidine bases produces significant amount of nitrogenous wastes of

1.        uric acid

2.      urea

3.       ammonia

4.      Hypoxanthine

5.      Xanthine

6.      Allantoin

Metabolic Wastes:

Generation of wastes is primarily done at metabolic level and these are called

metabolic wastes.

Examples:

1.      Urea, produced from the metabolism of amino acids;

2.      Creatinine, produced from muscle creatine;

3.      Uric acid, from nucleic acids;

4.      Bilirubin, end products of hemoglobin breakdown

5.      Metabolites of various hormones.

6.      Toxins produced within the body

7.      Toxins ingested into the body such as pesticides, drugs and food additives