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PHGY 209
David Ragsdale

Autonomic Nervous System ANS=Sensory +motor system— Regulates Visceral tissues and organs, Internal environment (Homeostasis) Activated independently Sympathetic (Fight or Flight) + Parasympathetic (rest and digest)— Cardiac and SM and glandular tissue Enteric System— Gut Autonomic motor neurons (Preganglionic neurons)—Outside the SC— Cell groups called Autonomic Ganglia (Ganglia= Cell bodies+ Synapses in peripheral) . Activated by Preganglionic neurons (cell bodies in the SC or brainstem) Opposing effects e.g. Cardiovascular reflexes Sympathetic: Stimulation ↑HR and the Strengths of contraction Parasympathetic: Simulation ↓HR and contraction Sensory Inputs Sensory info (From visceral organs)—Brain by vagus nerve (Head and neck)—Brain by glossopharyngeal and facial nerves ==Inputs Synapse in brainstem nuclei— Direct autonomic reflexes and project to higher brain areas (Hypothlamus and cerebral cortex)— regulates more complex autonomic responses Homeostasis Maintained through –ve feedback -Baroreceptor reflex— Sympathetic activation— in cardiac output +↑ in BP— activate pressure sensitive barareceptor neurons— parasympathetic activation— ↓BP and HR Stress— ↑Heart contraction and BP— ANS—↓BP Enteric Nervous System (Controls GI tract, pancreas and the gall bladder)— 100M neurons=SC
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