Define the sympathetic nervous system, Science

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.

Posted Date: 5/17/2013 4:08:10 AM | Location : United States

Related Discussions:- Define the sympathetic nervous system, Assignment Help, Ask Question on Define the sympathetic nervous system, Get Answer, Expert's Help, Define the sympathetic nervous system Discussions

Write discussion on Define the sympathetic nervous system
Your posts are moderated
Related Questions
Processing of minor cereals Maize, jowar, bajra, ragi and other small millets are important minor cereals of our country. They are also termed as coarse grains. They are widel

does the thickness seed coat effect the groth of the seed???

what is thermal velocity ofa material

what would i need to do to achieve a 7C in science , KS3??

Define the process of Soil acidity Acid soils are made more suitable for agricultural use by liming which raises the soil pH.  Soil acidity is commonly decreased by adding carb

Disease: All of us, at one time or another, have suffered from fever, aches. vomiting, nausea. diarrhoea, flu, cold, general weaknessetc. Illness can arise from a number of fac

Explain Oxidation of Fatty Acids ? Fatty acids released from chylomicrons and VLDL are transferred across cell membranes by passive diffusion, which depends upon the concentra

Types of soils Secure samples of soil from as many places as possible and place in glass jars. Try to get examples of a sandy soil, a loam soil, a clay soil, a soil rich in dec

Please furnish me with the basic restoration plan for the Marshall wetland located in Liberia. This wetland is of mangrove type, has invasive species (c. Odorata, has a physical p

Explain the Common Tests during Pregnancy Pregnancy, as you may have realized, is a period of physiological stress. To ensure a successful pregnancy, few common tests are recom