Question

Compare and contrast the kidneys between fish, Amphibians, and Mammals. What are the differences and similarities? What does a loop of henle allow, what happens to the ability of a mammal that has a longer loop?

Answer 1

Kidneys is an organ which filter waste materials out of the blood and pass them out of the body as urine. It regulate blood pressure and the levels of water, salts, and minerals in the body. Also it produce hormones that control other bodyfunctions

Mammalian kidneys have two major roles (a) Regulating the internal salt and water concentrations of the body

(b) Excreting the nitrogenous waste that are produced by metabolism.

Their other functions include

• Regulation of osmolarity.
• Regulation of ion concentrations
• Regulation of pH.
• Production of hormones.
• Our two kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine per day, composed of wastes and extra fluid. Each kidney is made up of about a million filtering units namely nephrons. The nephron includes a filter, called the glomerulus, and a tubule. It undergoes ultra filtration via glomerulus of blood which is circulating through afferent and efferent arteriol. Vasa recta, distal and proximal convoluted tubule, collecting duct. There is counter current mechanism and also urine production. Transport of sodium pottasium water and other excreta also undergoing.
• To conserve water mammals kidneys excrete small amounts of concentrated urine.
  For saltwater fish salt from the outside water diffuses into the fish and water leaves by osmosis so that water must be conserved and excess salt must be removed. This is by producing small amounts of concentrated urine.
  The water enters the fish by osmosis and salt leaves by diffusion in fresh water fishes, hence excess water must be removed and salt be conserved. This is done by producing large amounts of dilute urine.
• Amphibian kidney

  Functions:

  Device for excreting excess water. The permeable skin of the frog provides an easy route for the fresh water of its pond to enter by osmosis. As amphibians also spend time on land. Then the problem is to conserve water, not eliminate it. The frog adjusts to the varying water content of its surroundings by adjusting the rate of filtration at the glomerulus.

  Renal portal system is present to carry away materials reabsorbed through the tub when blood flow through the glomerulus is restricted, The frog is also able to use its urinary bladder to aid water conservation.

• When in water, the frog's bladder quickly fills up with a hypotonic urine.
• On land, this water is reabsorbed into the blood helping to replace water lost through evaporation through the skin.
• Hormonal control similar to mammalian ADH
• Loop of Henle, long, U-shaped portion of the tubule which conducts urine within each nephron of the kidney of reptiles, birds, and mammals.
• A part of the nephron called the loop of Henle has a thin descending limb, a thick ascending limb (permeable to sodium chloride which passes out of the tubule into the medullary tissue surrounding it) and fluid entering the descending limb contains sodium chloride and other salts, urea and other chemicals tht which filtered out from the blood.
• Most of the mammals with relatively long loops of Henle for their body size tend to have greater than average urinary concentrating ability