Biology Notes

Excretion in Invertibrate Excretion in Planaria Habitat : Planaria is a fresh water invertebrate.   Excretory product: planaria remove ammonia and it is ammonotlic. This excretion occurs by two methods, diffusion, specialized excretory system. Excretory organs: Planaria has simple tubular excretory system called protonephiridia. Protonephridia arranged in two longitudinal trunk one on each side of the body. Each track consists of a network of tubules without internal openings. These tubules divide into small branches which open in flame cells. Tubules open on the outside by small opening called nephridiophores. Structure of flame cell: Flame cells are club shaped hollow cells. Each flame cell contains nucleus, cytoplasm and internal cavity. Group of cilia is present in the cavity. Cilia perform a movement like a flame of candle. Flame cells also has many cytoplasmic elongations. Mechanism of excretion: Flame cells absorb wastes and push them into the c...

Nitrogenous Wastes Of Animal: Waste Products Of Animals: The nitrogenous wastes are urea,ammonia and uric acid . These all wastes are not removed by the same animal. These wastes are produced and excreted by different animal which are living in different habitats. The type of nitrogenous waste and their excretion depend upon the habitat of an animal. 1.Ammonia (NH3): It is the excretory product of aquatic animals ,developes by the break down of amino acids,harmful to the living cells,excreted by diffusion and highly soluble in water. About 500 ml of water is needed to remove one gram of ammonia . Animals those excrete ammonia are called ammonotelic . Examples: Eartworm, protozians, sponges and fishes etc. 2.Urea {CO (NH2)2}: It is the excretory products of mostly land animals ,produced by the liver from ammonia,less toxic than ammonia and can be store in the body for short time. One gram of urea require 50 ml of water for excretion. Animals those remove urea are...

Connective tissue Connnective tissue: Consisting of ground substance and fibres,in which various connective tissue cells are inserted. Function Connective tissue supports organs and cells,helps in exchange of nutrients and wastes between the blood and tissue,protects against microorganism, repair damaged tissue and stores fat.  Extracellular matrix The extracellular Matrix helps in the transfer of nutrients and waste material between cells of connective tissue  and the bloodstream. Ground substance Ground substance is a colourless, gel-like substance in which the cells and fibres of connective tissue are inserted. it is a complex mixture of glycosaminoglycans, proteoglycans and glycoproteins . Ground substance assist as a lubricant,helps to avoid invasion of tissue by foreign agents, and withstand un the effect of forces ocompression. Fibres collagen,reticular and Elastic are long, slender protein Polymers present in different parts in different ...

Golgi Bodies And Centrosome Golgi bodies Golgi bodies were discovered by  camelo Golgi in 1898.  These are present in animal and also in plant cells.  The Golgi bodies are composed of phospholipid and protein, they contain 3 to 20 sacs. The  Golgi apparatus  is a collection of membrane enclosed in sacs (cisterns)  that are  stalked like dinner plates. These cisternae are associated with vesicle  called Golgi vesicles. The Golgi complex is a complex system of interconnected tubules,  these tubules are present around Central stocks. One or more Golgi apparatus are present in all Eukaryotic cells.  Golgi is directed at proper glycosylation of protein and lipids.  There are more than 200 enzymes that function to add remove are modified Sugars from proteins and lipids in the Golgi apparatus.  The Golgi apparatus in polarized structure with  cis and trans sides. Newly synthesized proteins bud off from the gr...

Tissue  group of cells similar in structure origin and function. Term Tissue was given by French anatomist and physiologists Bichat ,term tissue was already given by N.Grew with plant anatomy. Study of tissue is called Histology  or microscopic anatomy. Fther of Histology Bichat . Epithelium   origin : Ectoderm,Endoderm and mesodermal. Definition :  It is defined as a collection of closely opposed cells with a Samal amount of intracellular matrix. The layer of cells rest upon a non cellular basement membrane . in basement membrane 2 layers are present. upper is basal lamina secreted by epithelial layer and  formed of glycoprotein and mucopolysaccharides which are secreted by epithelial cells. lower is reticular lamina it is part of connective tissue consist of reticular fibres and collagen fibres and a part of underlying connective tissue.  Epithelial cells are joined together by cellular junction between adjacent cells such as de...