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

Explain the term - ants, Explain the term - Ants  Ants are the most wid...

Explain the term - Ants  Ants are the most widespread species of insects in soil and consume plant residues, but are more active in humifying insects than plants.

Advantages of proteins, Advantages of Proteins Proteins are compounds...

Advantages of Proteins Proteins are compounds of carbon, hydrogen, oxygen and nitrogen. On an  average, proteins contain 16% nitrogen. Most proteins also contain sulphur and

Nuclear fission, Nuclear Fission: Splitting the Atom  You know  that ...

Nuclear Fission: Splitting the Atom  You know  that atoms are made up of a nucleus and electrons moving around the nucleus, and the nucleus  is made up of protons and neutron

Explain the hyposecretion during childhood, Explain the Hyposecretion durin...

Explain the Hyposecretion during Childhood Hyposecretion during childhood: Due to deficiency of growth hormone or its receptors, stunted growth of the skeleton and organs occur

How does our body know ''what to do'', How does our body know 'what to do' ...

How does our body know 'what to do' Feeling, knowing, doing anything depends on special structures called nerves. Neuronal cells in the body act as various messengers according

The movement of a glacier, Which is primarily involved in the movement of a...

Which is primarily involved in the movement of a glacier: gravity

Define nerve cell morphology, Define Nerve Cell Morphology The neurons ...

Define Nerve Cell Morphology The neurons in the mammalian nervous system occur in a variety of shapes and sizes. A typical cell has a cell body, the dendrites, axon and its ter

Soil formation, how do temperature affect the soil

how do temperature affect the soil

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