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

Zirconium, What reacts with zirconium/

What reacts with zirconium/

, What is the distance of the sun from eart

What is the distance of the sun from earth

Explain dacrocystography, Question 1. Why magnification technique is us...

Question 1. Why magnification technique is used in radiography? How it is performed? 2. Explain Dacrocystography. 3. Discuss the pre requisites for fluoroscopic study of

Steps involved during preparation of raw materials, Q. What are the prelimi...

Q. What are the preliminary steps involved during preparation of raw materials? Preliminary steps involved during preparation of raw materials include cleaning, peeling, cuttin

Test for studying suitable chemical treatment, Test for studying suitable c...

Test for studying suitable chemical treatment for changing the chemical nature of iodine Reactivity of iodine is tested with 1.  Water and, 2.  Sodium thiosulphate soluti

Define eco-labelling, Question 1 Define Eco-labelling. Explain the envi...

Question 1 Define Eco-labelling. Explain the environmental importance of eco-labelling with examples Question 2 Discuss the elements of environmental roadmap for eco

Astronomy, Describe the process of gas capture that helped to build the Jov...

Describe the process of gas capture that helped to build the Jovian planets?

The difference between weight and pressure, The difference between weight a...

The difference between weight and pressure Make two square blocks of wood, one much lesser than the other, and link them together as shown in the diagram. Press every of these

Life in forests, Life in Forests: Trees are the pillars of  the fores...

Life in Forests: Trees are the pillars of  the forest upon which much of  the other forest life is shaped. Associated with  them, there may be more than a thousand kinds of s

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