MMED1005 Lecture 8: Week 4 lecture 2
7 Jun 2018
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Main points:
The autonomic nervous system has 3 divisions, defined by their anatomy.
- Sympathetic
o Preganglionic nerves from the central region of the spinal cord
o Ganglia are distant from target
o Final transmitter NA
- Parasympathetic
o Preganglionic nerves from the brain and sacral spinal cord
o Ganglia near the target
o Final transmitter ACh
- Enteric
o No specific ‘preganglionic’ nerves
o Ganglia near target
o Complex ganglion-to-ganglion activity, range of final transmitters
For all 3, within the ganglia, the neurotransmitter is ACh
AUTONOMIC NERVOUS SYSTEM
The ANS is responsible for regulation most of the bodily functions that cannot be controlled
by conscious effort, e.g.:
- Movements of the intestine
- Heart rate and blood pressure
- Focusing and iris adjustments in the eye
The ANS has 3 divisions: (defined by their anatomical differences)
- Sympathetic
- Parasympathetic
- Enteric
Sympathetic – basic plan:
- Sympathetic axons to various organs come from cells that are in ganglia (groups of
nerve cell bodies) that are mostly in a ‘chain’ that runs beside the spinal cord on
either side
- Some come from other large ganglia in the thorax and abdomen.
- These axons are therefore known as sympathetic postganglionic fibres
- The axons providing input to the sympathetic ganglia (preganglionic fibres) come
from cells in the spinal cord, and leave the spinal cord in the middle region
Sympathetic nerves:
- Preganglionic axons leave the middle region of the spinal cord to synapse in the
sympathetic chain of ganglia beside the cord, or in other large ganglia
- The postganglionic axons go to a large number of organs
Sympathetic – Neurotransmitters and receptors
At the ganglion:
- Acetylcholine (ACh)/Nicotinic receptor (type N2)
At the final target:
- Noradrenaline (NA)/Alpha or Beta receptor
Document Summary
The autonomic nervous system has 3 divisions, defined by their anatomy. Sympathetic: preganglionic nerves from the central region of the spinal cord, ganglia are distant from target, final transmitter na. Parasympathetic: preganglionic nerves from the brain and sacral spinal cord, ganglia near the target, final transmitter ach. Enteric: no specific preganglionic" nerves, ganglia near target, complex ganglion-to-ganglion activity, range of final transmitters. For all 3, within the ganglia, the neurotransmitter is ach. The ans is responsible for regulation most of the bodily functions that cannot be controlled by conscious effort, e. g. - movements of the intestine. Focusing and iris adjustments in the eye. The ans has 3 divisions: (defined by their anatomical differences) Sympathetic axons to various organs come from cells that are in ganglia (groups of nerve cell bodies) that are mostly in a chain" that runs beside the spinal cord on either side. Some come from other large ganglia in the thorax and abdomen.
