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

Lysosomes, Lysosomes Lysosomes are small vesicles which are bounded ...

Lysosomes Lysosomes are small vesicles which are bounded by a single membrane & contain hydrolytic enzymes in the form of minute crystalline or semi crystalline granules of

What are the venous of the valves system, Q. What are the venous of the val...

Q. What are the venous of the valves system? What is their function? The valves of the venous system are structures inside the veins that permit blood to flow only in the norma

Explain the adverse effects of rifamycin, Adverse effects of rifamycin  ...

Adverse effects of rifamycin  No severe adverse effects were observed in clinical trials with rifaximin. There have been a few postmarketingeports of hypersensitivity reactions

Relation between fecundation and end of the meiotic process, Q. What is the...

Q. What is the relation between fecundation and the end of the meiotic process during oogenesis? The oocyte II only completes the second meiotic division (interrupted at metaph

What are the main types of cancer that affect humans, Q. What are the main ...

Q. What are the main types of cancer that affect humans? An Excluding skin cancer, that are the more easily detected and so cases are registered in larger number, the main type

Can you explain diabetes mellitus, Q. What is diabetes mellitus? Diabet...

Q. What is diabetes mellitus? Diabetes mellitus is the disease caused by action or deficient production of insulin and the consequent high blood glucose level and low glucose u

Prospects of meat products, P r o s p ec ts of meat products The ...

P r o s p ec ts of meat products The demand for convenience meat based fast food is ever increasing due to rapid industrialization and urbanization, higher standards of l

Head - structure of the sperm, Head - Structure of the Sperm It exhib...

Head - Structure of the Sperm It exhibits a diversity of shapes in different animal groups, e.g., spherical (teleost fishes), rod or lance shaped (amphibians), spirally twist

Explain dietary fibre - thyphoid, Dietary fibre Dietary fibre: Typhoid ...

Dietary fibre Dietary fibre: Typhoid patient has an inflamed intestinal mucosa, which can be easily perforated  and  ulcerated leading  to internal  haemorrhage. Thus foods hig

Prototheria, prototherians are unfinished mammals

prototherians are unfinished mammals

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