your autonomic nervous system is also your automatic nervous system in that it runs
in the background and controls all kinds of things so you don't have to think about it
so it's autonomic motor neurons that innervate smooth muscle cardiac muscle and glands visceral
sensory neurons so that you have sensation from your hollow organs and integrating centers in
the central nervous system there are two further subdivisions within your autonomic nervous system
the parasympathetic or rest and digest nervous system and the sympathetic or fight-or-flight
nervous system and it's an ongoing balance between the two systems if you're awake which I'm assuming
you are if you're watching this lecture you're a little bit more on the sympathetic side if you're
completely asleep just sitting there in your chair then you're definitely in parasympathetic mode the
autonomic nervous system is a two neuron chain if you remember when we talked about somatic
motor systems we talked about a neuron and alpha motor neuron in the spinal cord that went out and
innervated a skeletal muscle in the periphery and it was one neuron with one axon that went to the
muscle in the autonomic nervous system it's a two neuron chain and that there is one neuron within
the central nervous system either the brainstem or the spinal cord which then sends an axon out
to a ganglion and in this example we have the sympathetic chain ganglion with the cranial
nerves there are specific ganglia associated with the different cranial nerves so it's a and
then those ganglionic neurons are the ones that send the axon out to the target so somatic one
neuron one axon out to the muscle autonomics both parasympathetic and sympathetic a tuna run chain
neuron one is in the CNS either the brainstem or spinal cord that neuron synapses with a neuron and
which is pictured here the ganglionic neuron is then the the neuron that sends its axon to the
target which is going to be smooth muscle cardiac muscle or a gland the sympathetic nervous system
is also termed the thoracic nervous system to some degree because it's first neuron in the
chain the CNS neuron lives within the spinal cord between t1 and l2 the sympathetic nervous
system is responsible for increasing respiratory rate increasing your heart rate increasing your
blood glucose dilating your pupils and relaxing your gut all of these responses are there to help
you fight or flee so run away from the tiger or turn around and and fight with the tiger which
I wouldn't recommend but think about you need increased blood glucose because your muscles
need more energy dilated pupils you want more light to come in so it's like all the better to
see you grandma so you have more light coming in so that you can see the danger in front of
you the parasympathetic nervous system is cranial and sacral in that the preganglionic neurons for
the parasympathetics are within the brainstem and in the sacral part of the spinal cord and
this is our rest and digest system so you have a decreased respiratory rate decreased heart rate
decreased blood glucose because you're on the way to storing on everything that you've just
digested and constricted pupils because like I said it's the rest and digest so the going
to sleep you want less light coming in and busy digestive system busy got lots more peristalsis
because you're digesting so what would I like you to know about these basic components of
the autonomic nervous system so what are the two divisions the two subdivisions of
the autonomic nervous system what are their basic functions and then what effects does each of these
subdivisions have on heart rate respiratory rate gut activity blood glucose and the size
of the pupil if you understand all of these concepts then you're ready for the assessment