PNS Flashcards
(19 cards)
How many nerves makes up the PNS?
12 cranial and 31 spinal (all pairs)
how are nerves in the PNS organized when signaling the CNS
from organs = Visceral afferent
from ‘walls’ = Somatic afferent
What is the umbrella term for PNS nerves to the CNS
sensory
how are nerves in the PNS organized when signaling tissues (hint movement)
for voluntary = somatic motor (efferent)
for involuntary = autonomic (efferent)
focusing on involuntary control of the PNS how is the autonomic nervous system subdivided
1) Sympathetic
2) Parasympathetic
3) enteric (specific to GI tract)
what is the role of the autonomic nervous system
involuntary control of smooth muscle, glandular secretions (exo/endo) and metabolism
describe how nerve fibers of the autonomic NS are GENERALLY organized
1) pre-ganglion soma in CNS
2) pre-ganglion terminus secretes ACh
3) soma of post-ganglion found in autonomic ganglion
4) dendrites of post-ganglion fiber express nicotinic receptors for ACh
5) terminus of post-ganglion secretes either NA or ACh
6) tissue expresses nicotinic or muscrinic receptors
what tissue is ONLY effected by the SNS of the autonomic NS
Blood vessels
describe how nerve fibers of the autonomic NS are different between the SNS and PNS
pre-ganglionic fibers are shorter in the sympathetic nervous system due to fast action required AND ganglion closer to CNS
Post-ganglionic fibers are shorter in parasympathetic NS due to GANGLION closer to ORGAN/TISSUE
What receptor is mainly expressed on the autonomic ganglion
nicotinic
What happens when ACh binds to nicotinic receptors on the ganglion
excitatory stimulation
what type of receptor is Nicotinic
ionotropic and ligand-gated
what ions move through nicotinic receptors?
Na+ and K+
what drugs stimulate nicotinic receptors on the ganglia
Nicotine
Dimethyphenylpiperazinium (DMPP)
Acetylcholine
what effect do drugs (agonists) have on nicotinic receptors on the ganglia
increased blood pressure
increased secretion
what drugs inhibit nicotinic receptors on the ganglia
trimetaphan
Hexamethonium (similar to Ach)
what is the main target for the autonomic NS and why
post-ganglion fibers as they have more variability in NT and tissue specificity compared to pre-ganglion fibers (only Ach and Nicotinic)
what makes targeting the autonomic NS difficult
local modulation
what can modulate the ANS
tissue dervived histamine/bradykinin
Co-transmitters e.g. ATP/NO/neuropeptides
