Advanced nervous systems - general trend in evolution, Biology

Advanced Nervous Systems - General Trend In Evolution

In higher groups of animals you will observe clear trends towards centralisation of the nervous system, to maximize effectiveness. The diffuse peripheral network becomes less conspicuous or not recognizable giving place to nerves made up of nerve fibers. The motor neurons and association neurons become mainly concentrated and centralised into masses known as ganglia. The increasing dominance of the association neurons that are the links in reflex pathways, makes possible more complex central pathways that form the structural basis of advances in integration. The sensory neurons become relegated to the periphery. This results in differentiation of functional tracts of neurites and nerves by which stimuli are brought to and carried out of the central nervous system. Thus better association or integration of afferent sensory stimuli along with meaningful efferent motor outputs become possible, resulting in more intricate and capable behavioral patterns. Perikarya become limited to the rind or cortex of the ganglia, the interior being made up of nerve fiber mass called neuropile where conspicuous pathways or tracts already evident in the lower groups, become developed. The development of giant fiber system associated with the central nervous system further improves the efficiency resulting in enhanced speed of propagation of impulse and hence efficiency of response to stimuli. With one end of the animal always directed forward throughout locomotion, an anterior end and bilateral symmetry become established. The anterior end becomes more significant with most sensory organs becoming associated with this end. Naturally, the ganglia become better developed and much more highly organized in this region, giving rise to the structurally and physiologically more complicated brain dominating over the whole organism. This is the direct result of cephalisation.

Posted Date: 2/4/2013 6:43:20 AM | Location : United States







Related Discussions:- Advanced nervous systems - general trend in evolution, Assignment Help, Ask Question on Advanced nervous systems - general trend in evolution, Get Answer, Expert's Help, Advanced nervous systems - general trend in evolution Discussions

Write discussion on Advanced nervous systems - general trend in evolution
Your posts are moderated
Related Questions
New advancements and discoveries related to oogenesis

Define Buffers and Buffer Solutions? Solutions containing both weak acid and their salts or solutions containing weak hydroxides and their salts are referred to as buffer solut

Explain the Riboflavin content of RBC - Riboflavin? The erythrocyte glutathione reductase assay, with an activity coe cient (AC) expressing the ratio of activities in the prese

Radiobiology : This is the study of effects of radiations on living organisms. Radiobiology is a branch of science which concerned with the action of ions. Radiobiology is the radi

Determine the Modification of native starch Modification of native starch can be either physical or chemical. Chemical modification includes reaction of starch with  acid or al

Explain about the Cardiovascular and Circulatory System? Aging affects the cardiac muscle causing a diminished resting cardiac output. The capacity of myocardium for cellula

Explain what is Fern Allies - Lycopophyta ? Fern allies are those groups of vascular (with conducting vessels) plants that have close ties to the ferns. Sometimes they are refe

Q. Classify biomaterials and list some examples? Biologic classification is based on tissue response and systemic toxicity effects of the implant and is divided into three clas

Glucose-6-phosphate to Glucose Glucose-6-phosphate to Glucose : Glucose-6-phosphate  is converted to glucose  by glucose-6-phosphatase which is present in intestine, liver and

Individual components of biodiversity provide an unbeliev able wide range of products that are used to enhance the lives of people in all countries of the world. It is the diversit