Platyhelminthes - nervous systems, Biology

Assignment Help:

Platyhelminthes - Nervous Systems

Among Platyhelminthes, you will observe that turbellarians have a brain and three to five pairs of longitudinal nerve cords extending from the brain to the posterior end. They are positioned along dorsal, lateral and ventral aspects. The cords are connected together through means of commissures. The commissures are in turn connected to a sub-muscular nerve plexus.

198_Platyhelminthes.png

Figure: Planarian flatworms have a ladder-type nervous system. Cerebral ganglia in the head region serve as a simple brain and, to some extent, control the rest of the nervous system.

So, the system is not only sunk deeper into the sub-muscular position, but it does not correspond to the real primitive plexus at all. The motor and association neurons are mainly confined to the brain and the cords all along their periphery surrounding the central neuropile. One pair of these longitudinal cords becomes conspicuous, the others tending to become weaker finally disappearing thus giving rise to the typical ladder such as nervous system. With the development of the central nervous system, movements become more co- ordinate. Parts of the animal can keep spontaneous movements and show co- ordination of responses in most species of this group, just only if it contains portion of the nerve cord. The brain appears to have started exerting a dominating affect in this group.


Related Discussions:- Platyhelminthes - nervous systems

How to investigate mitral regurgitation by echo, Q. How to investigate mitr...

Q. How to investigate mitral regurgitation by Echo? 2 D echocardiography will help determine the morphology and etiology of mitral regurgitation. Rheumatic mitral regurgitation

Skin, what is the warmest and coldest parts of the boy

what is the warmest and coldest parts of the boy

Extractive use of biodiversity, Q. Extractive use of biodiversity? This...

Q. Extractive use of biodiversity? This includes direct use such as harvesting of wild plant species for use as food, fuel, fodder, fibre, shelter or medicine and hunting anima

What are the illustrations of the civil law, What are the illustrations of ...

What are the illustrations of the civil law? Illustrations of the civil law: Illustrations of civil actions are defamation of breach, character of contract, trespassing or

What is sanning membrane proteins, Which of the following is true for the f...

Which of the following is true for the following spanning membrane proteins? A. The mAChR (muscarinic Acetylcholine Receptor) is a spanning membrane protein located in the memb

What happens within the cell in the first interface period, What are the ev...

What are the events that mark the beginning and the end of the first interphase period? What happens within the cell in this period? The first interphase period is the G1. It s

Explain hair changes - clinical signs of kwashiorkor, Explain Hair changes ...

Explain Hair changes - clinical signs of kwashiorkor? In kwashiorkor, the hair loses its healthy sheen and becomes silkier and thinner. It takes coppery red colour (referred to

Explain somatic hybridisation, a) Explain somatic hybridisation? b) De...

a) Explain somatic hybridisation? b) Describe the various steps involved in the process. Mention any two uses of somatic hybridisation

Endocrine glands - placenta, PLACEN T A - Placenta is the intimate...

PLACEN T A - Placenta is the intimate connection between the foehls and the uterine wall of the mother to exchange the materials. Placenta is a tempormy endocrine gland

Genetics, The involuntary muscle movement is also genetical sk question #M...

The involuntary muscle movement is also genetical sk question #Minimum 100 words accepted#

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