Structural variations in vertebrate kidney, Biology

Assignment Help:

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.


Related Discussions:- Structural variations in vertebrate kidney

Which are the most important inorganic molecular substances, Q. Which are t...

Q. Which are the most important inorganic molecular substances for living beings? Ans. The most important inorganic substances for living beings are mineral salts, water,

Define food availability and food access, Define Food availability and Food...

Define Food availability and Food Access? Food availability: This refers to availability of necessary types of food in sufficient quantity, to the individual. The sources may b

The cross between a tall pea plant and a short pea plant, In peas, tall pla...

In peas, tall plants are dominant to short plants. A cross between a tall pea plant and a short pea plant results in half the progeny being tall, and the other half being short. Th

Advantage of using the regulatory strategy of enzyme, You have two enzymes,...

You have two enzymes, 1 and 2. Both convert substance A into substance B. 1 is inhibited by B, because B partially blocks the active site and will not allow more A to enter. 2 is i

Determine the human genome project, List three important discoveries that r...

List three important discoveries that resulted from the Human Genome Project. Answers should contain three of the following: Only about 2 percent of the human genome encodes p

Pre-mating isolating mechanisms, We mentioned earlier that pre-mating mecha...

We mentioned earlier that pre-mating mechanisms are concerned with the prevention of occurrence of interspecific crosses. In such cases, a) the potential mates do not meet in wh

Which is needed to stimulate the activity, Synthesis of fatty acids require...

Synthesis of fatty acids requires the movement of citrate out of the mitochondria. This occurs under conditions of high levels of acetyl CoA which is needed to stimulate the activi

Define subphylum chelicerata, Define Subphylum Chelicerata - classes Arachi...

Define Subphylum Chelicerata - classes Arachinda AM merostomata? The subphylum Chelicerata includes familiar horse shoe crab, spiders, scorpions, ticks and mites. 1. Body consis

What is speciation, What is speciation? The Speciation is the process b...

What is speciation? The Speciation is the process by which different species emerge from a common ancestor species. The Speciation generally begins when populations of the same

Nutrient budgets - nutrient cycles, Nutrient Budgets - Nutrient Cycles ...

Nutrient Budgets - Nutrient Cycles Nutrients are constantly being added and removed by natural and artificial processes. The measure of the input and outflow of nutrients thro

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd