Platyhelminthes - nervous systems, Biology

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.

Posted Date: 2/4/2013 6:46:25 AM | Location : United States







Related Discussions:- Platyhelminthes - nervous systems, Assignment Help, Ask Question on Platyhelminthes - nervous systems, Get Answer, Expert's Help, Platyhelminthes - nervous systems Discussions

Write discussion on Platyhelminthes - nervous systems
Your posts are moderated
Related Questions
#what is naturalistic theory?

Define Absorption of Zinc - Micro Minerals? Like iron, zinc also needs to be liberated from food prior to absorption. During digestive process; proteases, nucleases and hydroch

organisms and their excretory organelles

Q. Accessory Food Substances or Vitamins ? Bacteria also vary in their need for vitamins or accessory growth factors. Some microorganisms are unable to synthesize some or all o

Q. What is the endocrine function of the placenta? The placenta is not a permanent gland of the endocrine system other than this it also has endocrinal function. The placenta p

Is the esophagus a muscular organ? Why even in a patient lying totally flat on a hospital bed can the swallowed food reach the stomach? The esophagus is a predominantly muscula


What are the possible sources of human embryonic stem cells? Embryonic stem cells can be derived from individual cells of an early embryo, from blood cells in the umbilical co


Psychotropic Drugs - Act on brain and effect its normal functioning slow down and interphere in the functioning of the nervous system. These drugs alter behaviour, consciosn