Structural variations in vertebrate kidney, Biology

Structural Variations in Vertebrate Kidney

The structure of the vertebrate kidney is by no means universal. The mammalian kidney consists of an outer granular cortex and an inner striated medulla. The granular appearance of the cortex is due to the presence of glomeruli in this region. Medulla looks striated due to the parallel arrangement of blood vessels and tubules of the nephrons. In fishes, amphibians and reptiles, the renal tubules are short, are devoid of Henle's loop and there is no clear cut distinction between cortex and medulla. In birds there is some degree of spatial organisation of the nephrons so that a small central medulla can be discerned from the outer cortex. This division into cortical and medullary regions is most pronounced in the mammalian kidney.

It is the presence of Henle's loop that enables the avian and mammalian kidney to produce hyperosmotic urine. The ureteral urine in other vertebrates is either hypoosmotic or at best isosomotic to blood. However, terrestrial reptiles and birds produce a semi-solid or solid urine due to reabsorption of water in the cloaca. In birds and mammals, the ureteral urine itself is hyperosmotic to blood. The maximum urine osmolarity attained by the avian kidney is only about twice that of plasma. The urine concentrating ability of the kidney in mammals is related to the habitat. Desert animals produce highly concentrated urine and freshwater animals produce very dilute urine. The kidneys of some desert mammals can produce a urine which is 25 times more concentrated than the plasma. The beaver which has access to abundant water in the environment, on the other hand, has kidneys with only moderate ability to concentrate the urine.

Posted Date: 1/16/2013 2:11:43 AM | Location : United States







Related Discussions:- Structural variations in vertebrate kidney, Assignment Help, Ask Question on Structural variations in vertebrate kidney, Get Answer, Expert's Help, Structural variations in vertebrate kidney Discussions

Write discussion on Structural variations in vertebrate kidney
Your posts are moderated
Related Questions
Define Absorption, transport and Excretion of phosphorus? As you have seen that food contains both organic and inorganic phosphorus, but most of it is absorbed in its inorganic

How much Fats should be taken for management of obesity? Fats, being a concentrated source of energy need to be restricted. Excess dietary fat promotes much more weight gain th

What are the three major groups into which mammals are divided? The three groups into which mammals are divided are: monotremes (or prototherian, e.g., platypus), marsupials (o

What is cellulose? Cellulose is a long-chain polymeric polysaccharide carbohydrate, of beta-glucose. It creates the primary structural component of green plants. The primary ce

What does S-shaped pattern of population growth show? How is J-shaped pattern dissimilar from it and why?

Why d scientists pick hydrogen as the basis for MRI scanning? Name of the human body that do not appear in an MRI scan. Explain thermal stratification? How does thermal stratifi


Define Exclusion chromatography - basic separation technique? It is a chromatographic process, in which separation of the sample components takes place according to the molecul

What is meant by suction force of the plant cell? Does the suction force facilitate or make difficult the entrance of water into the cell? As the vacuolar solution is hypertoni

Pulse Oximetry: Procedure: Pulse Oximetry is a safe and  simple method of assessing oxygenation. An  advantage is  that this method  is noninvasive and continuous. Previously,