• Zoology

    METAMORPHOSIS

    Metamorphosis, in biology, striking change of form or structure in an individual after hatching or birth. Hormones called molting and juvenile hormones, which are not species-specific, apparently regulate the changes. These physical changes, as well as those involving growth and differentiation, are accompanied by alterations of the organism’s physiology, biochemistry, and behaviour. https://youtu.be/cgx8XdIpEos The immature forms, or larvae, are adapted to environments and modes of life that differ from those of the adult forms. These differences may be of significance in assuring that larvae and adults of the same species do not engage in direct competition for food or living space. Examples of metamorphosis include the tadpole, an aquatic larval…

  • Human anatomy

    EXCRETORY SYSTEM IN HUMAN

    Except for urinary bladder which is endodermal in origin, the whole excretory system is Except urinary bladder which is endodermal in origin, the whole excretory system is Except mesodermal. In human the kidney is retroperitoneal i.e., the kidney is located outside the coelomic cavity and is covered by peritoneum (coelomic epithelium) from the ventral side only. The size of each kidney is ~10 cm and it weighs is ~150 g. The two kidneys are asymmetrical, the Rt. being posterior to the Lt. Each kidney is bean-shaped with a groove (hilus) in the middle. The hilus is absent in frog’s kidney. The white fibrous connective tissue-covering around kidney is called renal…

  • Countercurrent-in-the-kidney.jpg
    Human anatomy

    Urine Formation

    3−steps are involved in the formation of urine A) Ultra filtration It is filtration under pressure. Glomerular capillary pressure (45 mm of Hg) favours filtration. The Colloidal osmotic pressure (due to plasma proteins, particularly albumin) acts against filteration. Its value is ~20 mm of Hg. The Capsular filtrate pressure, due to the glomerular filtrate in the Bowman’s capsule, also acts against filtration. Its value is ~10 mm of Hg. Net filtration pressure = 45 − (20+10) mm of Hg = 15 mm of Hg or 10 − 20 mm of Hg. Only 1/5 of plasma (20%) gets filtered from glomerulus per unit time. It is about 125 ml per minute.…

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