Formation of primary urine in malpighian tubules, Biology

Assignment Help:

Formation of Primary Urine in Malpighian Tubules

The formation of primary urine in malpighian tubules is due to secretion and not due to ultrafiltration. The cells of the malpighian tubules actively transport potassium from the haemolymph and concentrate it in the lumen. This results in the passive osmotic entry of water followed by the diffusion of other low molecular weight substances like salts, sugar, and uric acid. Figure will help you in understanding this phenomena. The rate of urine formation in insects is proportional to the concentration of K+ in the haemolymph. Thus, active transport of K+ is primarily responsible for generating urine flow in the excretory organs of insects.

2189_Malpighian Tubules of Insects.png

Figure: Functions of Malpighian Tubules of Insects

As the potassium-rich isosmotic tubular fluid moves towards the gut, there is secretion of molecules like uric acid and reabsorption of sugars and ions. However, major modification in the composition of the fluid occurs in the hind gut, particularly the rectum, where there is extensive reabsorption of water and physiologically important solutes like K+. Uric acid, which enters the hind gut as water soluble potassium urate, gets precipitated facilitating further withdrawal of water. Insects that live on liquid or wet food excrete large amounts of hypoosmotic liquid urine. On the other hand, insects that live on dry food produce extremely dry excreta. To facilitate water reabsorption, the rectum in terrestrial insects show modifications referred to as rectal glands or rectal pads.


Related Discussions:- Formation of primary urine in malpighian tubules

Explain the energy requirements during sepsis, Explain the Energy Requireme...

Explain the Energy Requirements during Sepsis? Patients suffering from septicemia with or without MODS are generally hyper-metabolic which results in weight loss. Critically il

Which term describes hereditary with high level of uric acid, In studies of...

In studies of human body, which of the below terms is used to describe hereditary condition associated with an excessively high level of uric acid in blood? a) Uric ptosis b

Explain isolated chloroplast thylakoids, In an experiment, isolated chlorop...

In an experiment, isolated chloroplast thylakoids were incubated at pH 4.0 with ADP and inorganic phosphate (Pi) added to the medium and then transferred to a medium having pH 8.0.

Results-types of surgery, Results: Early mortality for tricuspid valve re...

Results: Early mortality for tricuspid valve replacement is around six per cent. But depending on the patient's class of symptoms and the number of concomitant procedures, this c

The genetic code is a triplet code, In During translation, the series of an...

In During translation, the series of an mRNA molecule is examined from its 5' end by ribosomes that then synthesize an appropriate polypeptide. Together in prokaryotes and in eukar

Back cross, BACK CROSS When F 1  individual (Tt) is crossed with one of...

BACK CROSS When F 1  individual (Tt) is crossed with one of the two parents, either tall (TT) or dwarf (tt), such a cross is called the back cross. There are two possibilities

Explain about the dessicator, Explain about the Dessicator? A dessicato...

Explain about the Dessicator? A dessicator is used to prevent an item from absorbing moisture. It is able to accomplish this because of a chemical, known as the dessicant, is h

Define common complications with spinal trauma patients, Define Common comp...

Define Common complications with spinal trauma patients? Common complications with spinal trauma patients include pressure sores or decubitus ulcers, hypercalciuria and renal s

Local needs, Local Needs, Choices and Circumstances Beyond obvious cho...

Local Needs, Choices and Circumstances Beyond obvious choice for private sector, the best public-private balance for a country depends on its local culture and circumstances.

What are the functions of insulin and glucagon, What are the functions of i...

What are the functions of insulin and glucagon for the blood glucose control? Glucagon enhances glycemia and insulin reduces it. They are antagonistic pancreatic hormones. Gluc

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