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
Cori Cycle Skeletal muscles have some mitochondria, yet are competent of vigorous activity. as a output, the little stores of oxygen are rapidly depleted, causing the muscle ti

Advantages and Disadvantage of using Turbidity Measurement? Advantages 1. It is an easy, rapid and sensitive technique. 2. Turbidity measurement can be done without destr

The original DNA sequence when ,transcribed and translated would yield five successive valine residues. But the altered sequence would correspondingly read one aspartate and four s

What are passive and active immunization? According to the duration of the protection how do these types of immunization differ? Active immunization is that in which an antigen

Describe two pieces of evidence indicating that speciation does not always occur at the same rate. Some species of moths on the Hawaiian Islands appear to have evolved during t

Black disease It is a fatal peracute disease caused by Clostridium novyi Type B. It is associated with liver damage caused by liver fluke. The onset of the disease is rapid fo


what is a limited resourse needed by all cells?

sanguivarous mode of feeding in annelida

Q. Guidelines for the Family Members for Healthy Coping? - Patient and the family members should discuss the situation, change in role,time distribution, share of money and oth