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

Reproduction, write about asexual reproduction in mucor

write about asexual reproduction in mucor

What is an instance of a hypothesis, Q. What is an instance of a hypothesis...

Q. What is an instance of a hypothesis which may explicate why there is not a big representation of the class Reptilia found in Polar Regions? Beings of the class Reptilia are

Explain procedure for analysis of air of processing facility, Explain Proce...

Explain Procedure for Analysis of Air of Processing Facility? Now conduct the experiment following the steps enumerated herewith: 1. Label the Petri plates with nutrient aga

Human gene responsible for a form of muscular dystrophy, Graduate student D...

Graduate student Dee Innay works in a human genome lab, whose goal is to identify the human gene responsible for a form of muscular dystrophy (MD).  Dee has mapped the MD gene to a

Respiratory system of the phylum annelida characterized, Q. How is the resp...

Q. How is the respiratory system of beings of the phylum Annelida characterized? Respiration in annelids can be branchial or cutaneous. Cutaneous respiration takes place due to

Explain hydrogen transferring coenzymes, Hydrogen Transferring Coenzymes ...

Hydrogen Transferring Coenzymes This group consists  of  three  important coenzymes  all of  which  assist different enzymes  in oxidation-reduction reactions. These are: a

Wbc.., Ask question #Minimuwwm 100 words accepted#

Ask question #Minimuwwm 100 words accepted#

Draw a diagram of transverse section of the spinal cord, Draw a diagram of ...

Draw a diagram of transverse section of the spinal cord showing reflex are and label the following parts: (i) Afferent nerve fibre (ii) Grey matter (iii) Motor nerve fibre

Stereoisomers , Glyceraldehyde has a one asymmetric carbon atom the central...

Glyceraldehyde has a one asymmetric carbon atom the central one and so two stereoisomers  which is also known as optical isomers are possible, which is two forms of glyceraldehyde,

Fundamental structure of a virus, Q. What is the fundamental structure of a...

Q. What is the fundamental structure of a virus? Viruses are constituted of genetic material RNA or DNA covered by a protein capsule also known as a capsid. Some viruses, like

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