Unformatted text preview: Autonomic Nervous System Autonomic Nervous System
Autonomic nervous system (ANS) consist of two components: sympathetic/parasympathetic.
Most organs in the periphery are innervated by b
Parasympathetic: At rest, mediated by muscarinic (metabotropic) receptors
- Thoracic + lumbar autonomic nerves
Sympathetic: Times of stress ie fight or flight, good for ↑ blood glucose and cardiac activity
- Sacral autonomic nerves + cranial nerves
Parasympathetic (ACh) Sympathetic (NE) Heart Inhibits Excites Vascular smooth muscle Inhibits → vasodilation, ↓ bp Excites → vasoconstriction, ↑ bp Gut (digestion) Excites Inhibits Pupils Inhibits → constricts Excites → dilates Lungs Excites Inhibits Muscarine mimics parasympathetic stimulation of the heart i.e. ↓ HR, ↑ force
Atropine can block effect of vagal nerve stimulation (ACh release) and muscarine.
Somatic Motor Systems
Neurons travel directly from CNS → skeletal muscle i.e. no ganglia in between makes it faster
- Mediated by ACh nicotinic (ionotropic) receptors
- If ACh blocked at the neuromuscular junction: no breathing
CNS control of the ANS
Input to hypothalamus and solitary nucleus (in brainstem) from periphery
- Gives information about blood pressure, body temp, blood glucose
Output to periphery
- Helps regulate ANS and maintain homeostasis ...
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- Spring '13