>>11916302autonomic nervous system is part of the peripheral nervous system that acts automatically without concious effort
for example on the smooth cardiac muscles and the glands (we do not control it)
it is divided into 2 parts that work together in tone as the balance shifts according to the body's needs
though some parts of our body are only affected by one, for example the smooth muscles of blood vessels are only acted on by sns fibers to keep normal blood pressure by keeping them constricted
sympathetic nervous system (fight or flight response)
it arises from the thorax-lumbar regions of spinal cord, the fibers exit until they reach a nearby ganglia (basically a collection of neurons in the pns), once they are in that chain of ganglia, then they may follow 3 routes, some synapse immedietly with post ganglionic neurons, others go up or down before they synapse, some of them cross the chain without synapsing and this group travels further to reach collateral ganglia where it synapses, then the fibers run all the way to target organs
it increases the things we need to make certain reactions like we're under danger and also inhibits the things we don't need
e.g. it increases heart rate, increase breathing rate, dilutes the pupils, realease glucose, inhibits digestion&peeing
the effect of sns is very widespread because high divergence (1 pre ganglionic fiber : 20 post ganglionic neurons)
parasympathetic nervous system (rest and digest)
it arises from the cranial and sacral parts of the spinal cord, that's why it's called para it surrounds the sns region and travel to the parasymepathetic ganglia which is near the targets (the post ganglionic fibers are relatively short in comparision)
act when the body is under rest. lowers heart rate, breathing rate, normal pupils, store glucose, and more digestion&peeing
very low divergence compared to sns (1:4) so it's more specific localized responses
