Karius Autonomics ibook notes Flashcards
Movement: the Reflex
simplest level of integration between CNS and PNS occurring in the brain
afferent nerve
sensory, sends message to CNS about body or environment
efferent nerve
moto, sends command to PNS (then to muscles)
Simples reflexes
typically have just one synapse (two neurons involved: afferent and efferent) but may have two.
plan of a reflex
sensory information causes an AP to be delivered from the pre-synaptic neuron to the CNS where it synapses with a post-synaptic neuron, which initiates an AP down the efferent axon to a target muscle (alpha motor neuron based). Action potential from efferent causes an action potential on the muscle, exciting it and causing contraction.
Do reflexes require the brain to be involved?
All reflexes “notify” the brain by having a branch of the first neuron synapse or go to the brain, directly/indirectly
Reflexes in the ANS: part 1
the sensory component which is attempting to convey information about sensation internally and externally
Reflexes from the ANS: part 2
brain processing information received from ANS, similar to somatic side. this is all the information she has in the ibook on part 2.
the efferent side of ANS: part 3
message relayed to effectors (not skeletal muscle) –> smooth muscle and glands.
two parts: sympathetic and parasympathetic system
ANS anatomy, general considerations
always has two neurons, two synapses in the pathway going from the spinal cord to the effector organ in the periphery
ANS has how many neurons?
Two: one preganglionic (in the CNS) which synapse on a postganglionic neuron (outside the CNS).
ganglion
a collection of neuron cell bodies
equivalent of a nucleus in the brain
Pre-ganglionic neuron
small, sparsely myelinated B Fiber (relatively slow conduction velocity)
goes from CNS to a ganglion
B-fibers
Post-ganglionic neuron
small, unmyelinated type C fiber
C fibers
travels to actual target organ and synapses on that to do the brains command
ANS two divisions
sympathetic and parasympathetic
Parasympathetic
rest and digestL leave the CNS from the cranium and the sacrum
regardless of where they leave the CNS, the pre-ganglionic axons travel to the ganglion, which is located near the target tissue
Where is the “Ganglion” in the ANS?
on or near the target organ
Preganglionic fiber: short or long
long, has to be because it leaves from the cranium or sacrum and travels to the post-ganglionic target
Post-ganglionic fiber
short, only goes short distance
“PLS” nemonic
Parasympathetic, Long, then Short
