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

The effect of petrol on surface tension, The effect of petrol on surface te...

The effect of petrol on surface tension Being sure that the plate is has to be clean. It is wise to rinse the plate in cold water for a time before filling it. Instead of soap,

Clothing materials, clothing materials and their respective qualities

clothing materials and their respective qualities

Perceptual reasoning index, Mr. X was administered the Wechsler Adult Intel...

Mr. X was administered the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV), which is an individually administered test of a person's intellectual ability and cognitive s

Explain maintaining the ph balance, Explain maintaining the pH Balance ...

Explain maintaining the pH Balance You must be aware of the term pH. PH we know provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 i

Explain the dichromates or mild colour blindness, Explain the Dichromates o...

Explain the Dichromates or Mild Colour Blindness A dichromate individual possesses only two cone pigments. Lack of the red pigment, called protanopia, makes distinguishing of t

Explain the ketone bodies - abnormal constituent of urine, Explain the Keto...

Explain the Ketone bodies -  abnormal constituent of urine Ketone body is an intermediate breakdown product of fats in the body. It can be any of three compounds (acetoacetic a

Image caching, how to cache images in java or jsp without using .htaccess??...

how to cache images in java or jsp without using .htaccess??

Torque and equilibrium, equilibrium, Physics what is the effect of torque a...

equilibrium, Physics what is the effect of torque and equilibrium on taps, doors,handle bars and bicycles??

Calculate the specimen of carbon 14, Carbon l4 with a half-life of 5,568 ye...

Carbon l4 with a half-life of 5,568 years is used to date a sample of wood. Sample has l/8 the carbon l4 contained in a living tree of same species. Approximately how old is specim

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