W21-L4: Autonomic Nervous System Flashcards
Where do all the sympathetic pathways originate from?
all of sympathetic come out of thoraco lumbar region
Where do all the parasympathetic pathways originate from?
all of para are cranio (cranial nerves)-sacral
Do any autonomic pathways originate in cervical or lumbar enlargement?
No
What are the two columns of sympathetic ganglia?
Prevertebral ganglia
Para-verteberal ganglia
What are the pre-ganglionic fibres for both para and sympathetic fibres?
Lightly myelinated/unmyelinated, uses Acetylcholine on nicotinic receptors (longer in post-ganglionic)
What are the post-ganglionic fibres for both para and sympathetic fibres?
All unmeylinated, longer in sympathetic (NA, ACh on muscarinic) and parasympathetic ACh on muscarinic
T/F Autonomic pathways contrast with typical CNS circuits where glutamate and GABA are the primary transmitters
True
What is co-transmission?
More than one transmitter being released at one time
T/F More than one transmitter release site per axon in ANS to organs
True
What is extra-junctional receptors?
Receptors can be expressed remotely from the synapse
Where do the preganglionic neurons of the sympathetic lie in the spinal cord?
Intermediolateral cell column
What is the function of Paravertebral ganglia (sympathetic chain)?
primary source of vasoconstrictor neurons
What is the function of Prevertebral ganglia (sympathetic chain)?
primary source of neurons innervating non-vascular smooth muscle
eg airway, reproductive smooth muscle
What does divergence mean?
mechanism for coordinating effects in many tissues at once, Up to 200 ganglion neurons can be activated by one preganglionic neuron
What does convergence mean?
Prevertebral ganglion neurons integrate more signals from multiple inputs
What is the sympathoadrenal system?
adrenal medulla cells are innervated by sympathetic preganglionic
neurons release noradrenaline and adrenaline into the circulation broad activation of adrenoceptors throughout the body
What is the pelvic ganglia?
relay station; relatively little integration made up of parasympathetic ganglion neurons which have unusually long axons: vulnerable to surgically- induced injury and many sympathetic neurones
T/F sympathetic and parasympathetic systems always act antagonistically and in competition
False
What is an example of ANS genuine antagonistic actions?
Heart rate, Heart contraction, airway relaxation
What is an example of ANS functional antagonistic actions?
Pupil, bladder
What is an example of ANS different but not opposite actions?
serous Salivary vs mucous salivary, tear secretion, vasoconstriction
How do you distinguish sympathetic and parasympathetic nerves?
The only correct, unequivocal definition is anatomical: location of preganglionic neurons other properties are unreliable
T/F Most autonomic reflexes involve the brain (supraspinal reflex) rather than only the spinal cord (spinal reflex)
True
Where is the major integrative centre for autonomic function?
Caudal part of the NTS
What is the most important brain region for coordination of autonomic output?
Paraventricular nucleus
