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

Keep volume of water in body constant - function of kidney, Keep volume of ...

Keep volume of water in body constant - Function of Kidney Keep the volume of water in the body constant by removing excess fluid from the body. The kidneys regulate the volume

What are the climatic factors of fertilizer requirements, What are the Clim...

What are the Climatic factors of fertilizer requirements  These include temperature, rainfall and its distribution, evaporation, length of day and growing season.  A cool clima

Biologically compounds that contain oxygen and nitrogen, Q.Name two biologi...

Q.Name two biologically important compounds that contain both oxygen and nitrogen. Two biologically important compounds that contain both oxygen and nitrogen are: (i) Amino a

Recombinant DNA, how has Modern sequencing helped in our understanding of t...

how has Modern sequencing helped in our understanding of the human genome?

Spinal cord, Spinal Cord: The spinal  cord extends downwards from the  ...

Spinal Cord: The spinal  cord extends downwards from the  brain stem through the  protecting bony rings called vertebrae down the  centre of  the backbone, to the bottom of the

Explain abo blood grouping system, Explain ABO Blood Grouping System A...

Explain ABO Blood Grouping System As the name suggest, this is based on the presence or absence of 9 antigens A and B, on the surface of RBC. If either of these antigens is pr

Explain the respiratory adjustments, Explain the Respiratory Adjustments ...

Explain the Respiratory Adjustments Certain adjustments need to be made inside our body as well, to cope up with the varying environmental conditions, as well as, abnormal and

Fine-grained black limestone, Give a rock name for sample. Note that the co...

Give a rock name for sample. Note that the colour of this type of rock varies greatly, depending on the abundance of organic matter and iron oxides. Samples are both carbonate rock

How temperature of the earths layers is changed, How Temperature of the Ear...

How Temperature of the Earth's Layers is changed? How does the temperature of the Earth's interior change as one goes deeper within the Earth? As one might expect, the farther

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