Autonomic nervous system ( Preganglionic and Postgangiolnic in parasympathetic, sympathetic and enteric neurons / Chemical signals )
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- Preganglionic neurons in the parasympathetic, sympathetic and enteric neurons.
- Postganglionic neurons in the parasympathetic, sympathetic and enteric neurons.
- The length of the pre and post ganglia in the autonomic nervous system:
- What is the difference between the types of chemical signals between cell
autonomic nervous system consists from ( preganglionic )
1- parasympathetic neurons: preganglionic neurons come from medulla oblongata and the sacral region of the spinal cord and synapse in ganglia to or within the effector organ.
2- Sympathetic: preganglionic neurons come from thoracic and lumbar regions of the spinal cord , and synapse in ganglia away from the effectors organs.
3- Enteric neurons ( in stomach ) : it is a collection of nerve fibers that innervate the gastrointestinal tract and gallbladder.
autonomic nervous system consists from ( postganglionic )
1- parasympathetic neurons: postganglionic neurons extend from these ganglia to the tissues that innervate and regulate.
2- Sympathetic: postganglionic neurons extend from these ganglia to the tissues that innervate and regulate( same as parasympathetic) .
3-Enteric neurons ( in stomach ) : it is a collection of nerve fibers that innervate the gastrointestinal tract and gallbladder ( same as preganglionic neurons ) .
For the length of the pre and post ganglia in the autonomic nervous system
1- parasympathetic: preganglionic neurons is longer than postganglionic neurons.
2- Sympathetic: postganglionic neurons is longer than preganglionic neurons
What is the difference between the types of chemical signals between cell
1- local mediators( such as : histamine and prostaglandins ) :
- Are chemicals that are secreted by non-specific cell and act locally on the cells in their environment
- These chemicals are rapidly destroyed
- They do not enter the blood stream
- They are not distribution throughout the body.
2- Hormones:
- They are chemicals that are secreted by specialized endocrine cell.
- They are enter into bloodstream.
- They are distribution throughout the body.
3- Neurotransmitters:
Are chemical that are released from the nerve terminals to communicate between nerve cells and between nerve cells and effector organs.
All neurotransmitters and most hormones and local mediators are too hydrophilic to penetrate the lipid bilayer of target-cell plasma membranes.