Define the sympathetic nervous system, Science

Assignment Help:

Define the Sympathetic Nervous System

The sympathetic component of the autonomic nervous system is concerned with in- creasing the level of arousal and energy expenditure - primitive 'fight or flight' behaviour at times of stress. Alike the parasympathetic nervous system, the central integrating center for sympathetic activity is within the hypothalamus. This may be influenced by higher cortical centre. Efferent fibres descend from the hypothalamus within the intermediolateral columns of the spinal cord. As sympathetic fibres emerge from the central nervous system at spinal segments TI (thoracic) to L5 (lumbar), the sympathetic system is also known as the thoraco-lumbar outflow. Here 3 neurons are involved in covering impulses from the hypothalamus and medulla oblongata to effectors organs and tissues.

Neuron - 1: has its cell in the brain and its fibre extends to the spinal cord.

Neuron - 2: has its cell in lateral column of gray matter in the spinal cord.

Neuron - 3: has its cell in a ganglion (small mass of nerve tissue containing the cell bodies of the neuron) and terminates in the organ or tissue supplied.

 The preganglionic motor neurons of the sympathetic system arise in the spinal cord (lateral group column). They pass into sympathetic ganglia which are organized into two chains that run parallel to and on either side of the spinal cord. The neurotransmitter of the preganglionic sympathetic neurons is acetylcholine (ACh). It stimulates action potentials is the postganglionic neurons. The neurotransmitter released by the postganglionic neurons is noradrenaline (also called norepinephrine). The action of noradrenaline on a particular gland or muscle is excitatory in some cases, inhibitory in others.


Related Discussions:- Define the sympathetic nervous system

What is oxidoreductases, Oxidoreductases To this group (EC  1) beIongs al...

Oxidoreductases To this group (EC  1) beIongs all enzymes catalyzing oxidation-reduction reactions. Common  names  include dehydrogenases, oxidazes,  reductases  and  catalases.

Explain the transport of fructose - carbohydrates, Explain the Transport of...

Explain the Transport of Fructose - Carbohydrates Fructose is converted to glucose after it is being transported. This occurs before entering the portal blood. The conversion o

Explain the hyperinsulinism - insulin, Explain the Hyperinsulinism - Insuli...

Explain the Hyperinsulinism - Insulin Too much secretion of insulin or over treatment of a diabetic person with insulin may cause hyperinsulinism. In this condition, the blood

Hypothesis, Hypothesis: The next step is to formulate hypothesis. A  hy...

Hypothesis: The next step is to formulate hypothesis. A  hypothesis is a statement, put forward on the basis of reasoning, about the things that are being studied. It is an att

Cells, the structures that makes up a cell are called

the structures that makes up a cell are called

Requirements for wiring a plug to an appliance, Requirements Screw driv...

Requirements Screw driver - 1 Wire stripper - 1 6/16 A Plug -1 Electrical appliance (any, without plug) - 1

Antibody mediated immune system (amis), Antibody Mediated Immune System (AM...

Antibody Mediated Immune System (AMIS) In antibody-mediated immunity, the antibodies dissolved in blood, lymph and other body fluids bi nd the antigen and trigger a response to

Soil Science, A soil with a large buffering capacity can be expected to hav...

A soil with a large buffering capacity can be expected to have: A. A tremendous amount of iron oxides B. Little ability to retain basic cations C. A high ability to retain cation

State the Beneficial role of soil organisms, Beneficial Role of Soil Organi...

Beneficial Role of Soil Organisms The soil organisms play a significant role in the life cycles of plant and animals through decomposition, synthesis and transformation, in wh

2-4 plants, 2-4 plants, 6-12 primary consumers

2-4 plants, 6-12 primary consumers

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