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

Define precautions for estimation of iron in the solution, Define Precautio...

Define Precautions for Estimation of Iron in the Solution? 1. Washing of glassware for iron estimation is important. Insufficient washing for iron removal may cause fluctuation

Fst-01, Give reason for the benifits of our technological development not r...

Give reason for the benifits of our technological development not reaching all the strata of our society.

Define the sympathetic nervous system, Define the Sympathetic Nervous Syste...

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 - pri

Interpersonal relations, Interpersonal Relations Mr. X relates easily...

Interpersonal Relations Mr. X relates easily to others and describes himself in positive terms (Ho=38). He believes that others can be trusted and that they have his best int

Define benefits and constraints of multicellular organisms, Define Benefits...

Define Benefits and Constraints of Multicellular Organisms Some of the benefits and constraints of multicellular organisms are as follows: 1) There is a unique co-ordination

Controlling air pollution, Controlling Air Pollution: Now  let us  se...

Controlling Air Pollution: Now  let us  see, how air pollution can be controlled.  i)  Photochemical smog-eliminating  this would require large scale changes in life style

Aids, AIDS: You have learnt about infectious diseases. For centuries, d...

AIDS: You have learnt about infectious diseases. For centuries, death from infectious diseases was common and whole populations were often affected.  One of the remarkable achi

Temperature variations in glacial regions, Temperature variations in glacia...

Temperature variations in glacial regions In glacial regions of the world or during forest fires the rocks are exposed to extreme temperatures. Since the conduction of heat is

Mention the different methods of wheat milling, Q. Mention the different me...

Q. Mention the different methods of wheat milling? Three methods of wheat milling are stone milling, roller milling and fragmentation milling.

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