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 hyposecretion of insulin, Define Hyposecretion of Insulin You ma...

Define Hyposecretion of Insulin You may already be aware that an insufficiency of insulin in the body leads to the development of diabetes mellitus. It is caused by the degener

Judicious use of plant/animal material for lab, Judicious use of Plant/Anim...

Judicious use of Plant/Animal Material for Lab. Purposes Live or preserved biological material is an essential requirement in all bio-labs. This material needs to be brought in

Cholagouge action and absorptive function of bile, Cholagouge action and Ab...

Cholagouge action and Absorptive function of bile Cholagouge action: Bile acts as its own stimulus. Bile salts are absorbed from the intestine, carried to the liver and stimula

Explain the lubrication of food, Explain the Lubrication of food Dry fo...

Explain the Lubrication of food Dry food enters the mouth. It is moistened and lubricated by the saliva, before it can be made into a bolus ready for swallowing.

Explain cyanosis - histotoxic hypoxia, Explain Cyanosis - histotoxic hypoxi...

Explain Cyanosis - histotoxic hypoxia Cyanosis is a physical sign for causing bluish discoloration of the skin & mucous membranes. Cyanosis is caused by a lack of oxygen in the

Functions of adrenal sex hormones, Functions of Adrenal Sex Hormones Ad...

Functions of Adrenal Sex Hormones Adrenal androgens have only weak effects in humans. Their fictions are: 1. It is possible that part of early development of the male sex or

Explosives-storage of chemicals, Explosives : As defined earlier, explosiv...

Explosives : As defined earlier, explosives release a large amount of gas and energy in a very short time. These are of four basic types: Mixed gases - Usually the mixture

Human adaptation, 3 human adaptations to help differential survivability, a...

3 human adaptations to help differential survivability, and three re differential fecundity

Health Care Reform, What is your evaluation of the effectiveness of the U.S...

What is your evaluation of the effectiveness of the U.S. health care system in the context of delivery, finance, management, and/or sustainability? What are the issues that prompte

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