THE AUTONOMIC NERVOUS SYSTEM (ANS)
The autonomic nervous system is important in the physiological regulation of motivational-emotional states.
Its major function is that of maintaining homeostasis and adaptation.
The central nervous system affects the autonomic nervous system largely through the hypothalamus.
Hess observed that stimulation of the posterior hypothalamus produced sympathetic responses, whereas stimulation of the anterior hypothalamus, medial thalamus, and septum, was followed by significant parasympathetic responses.
Neurotransmitter difference between Sympathetic and Parasympathetic nervous system
- The major neurotransmitter of the sympathetic nervous system is norepinephrine.
- Norepinephrine does not get metabolized quickly and exists in large quantities outside the sympathetic nervous system nerve cells.
- Sympathetic stimulation affects the body quickly, within seconds, but does not have long-lasting effects.
- The hormones Norepinephrine and Epinephrine are released by the adrenal gland into the general circulation (bloodstream) when stimulated by the sympathetic nervous system.
- When they are released in the bloodsteam, their effects mimic those of sympathetic arousal.
- Their action may be slower, but have the same bodily reactions that are more long-lasting.
- The major neurotransmitter in the parasympathetic nervous system is acetylcholine (Ach).
- However, acetylcholine is easily broken down by an enzyme called acetylcholinesterase (Ache) that is released by the nerve cell.