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
Pattern of Limb Development The first visible sign of limb development is the appearance of ridge or thickening on each lateral side of the embryo of amniotes. The ridge call

MECHANISM OF GASTRULATION - It is most impotant stage of embryonal development, in which single layered blastula converts into 2 or 3 layered gastrula. During this stage,


A small drop of blood is required to perform the test and this can be easily obtained from the patient's fingertip. A large number of glucometer devices are easily available and t

Excessive Cantilever Cantilevers in implant dentistry are commonly used especially in the mandibular arch for edentulous patients receiving implant supported prosthesis. Cantil

Functional Properties of Starches Starch is a major source of energy (calories) in grains and tubers, and foods made from them. However, when starch is added to products as an

Blood Vessels There are three types of blood vessels. They are: 1) Arteries: Arteries carry blood from heart to different organs. They have thick wall. 2) Veins: Vein


how the optical rotaion occurs in glucose and ribose?

Explain Full Liquid Diet Full Liquid Diet:   This diet provides foods and fluids that are liquid or semi liquid at room temperature. The type of food provided may vary dependi