INTRODUCTIONMaintaining a stable internal environment, or homeostasis, is essential for the survival of complex animals. Living organisms must maintain a balance of salt and water and must continually eliminate toxic byproducts generated by metabolism. Organisms have developed various strategies to maintain a more or less stable internal environment. In animals with a circulatory system, blood usually passes through the excretory organs, commonly called the kidneys. In terrestrial animals, the kidneys not only play a major role in waste elimination, but are also the primary organs of osmoregulation. The kidneys are paired bean-shaped structures that are present in the lumber region along both sides of the spine and are retroperitoneal in nature. The kidneys are covered by a capsule of fibrous connective tissue and held in place by the renal fascia. The kidneys of mammals are of metanephric origin. The structural and functional units are called nephrons and there are one million of them per kidney. The kidneys receive blood through the renal artery and the blood leaves the kidney through the renal vein. Blood entering the kidneys undergoes pressure filtration, ultra-filtration and reabsorption, leading to the formation of urine. The kidneys regulate internal homeostasis by regulating the body's fluid and electrolyte balance. The main functions performed by the kidneys are blood filtration, urine formation, elimination of non-gaseous N2 waste in the form of urea, uric acid and ammonia, regulation of fluid volume and regulation of the volume of fluid and electrolytes leading to regulation. blood volume and blood pressure.OBJECTIVES• Study of the anatomical regions of the mammalian kidney (sheep kidney)...... middle of paper...... This pressure leads to pressure filtration, called ultra filtration. This filtration leads to filtration of the blood into blood filtrate and nephric filtrate. A larger diameter will reduce the pressure exerted by the blood on the kidney blood vessels, leading to adequate filtration. Q.2a) With increasing ADH concentration, the permeability of the collecting tubules to water b) Water retention results in an increase in fluid volume and a corresponding increase in blood volumec) Urine will be highly concentrated due to increased water reabsorptionQ.3 In the following conditions, ADH secretion will increase in the blood: Reduction in the volume of fluid in the body Decreased blood pressure of the body When the person drinks less water Hypovolemia, i.e. the reduction of body fluid volume