L10 & L11 - drugs affecting the SNS Flashcards
what are ganglia
clusters of cell bodies
what does SNS stimulate
increased HR vasoconstriction bronchodilation pupils dilate decrease smooth muscle contraction
where is SNS ganglia
close to spinal cord
what does disynaptic mean?
there are 2 synapses along the pathway (pre and post ganglionic ) compared to one synapse in somatic motor neurons
describe adrenal medulla (what is it)
modified post ganglionic neuron
is there ganglia in the pathway from CNS to adrenal medulla?
no, the adrenal medulla is modified ganglia
what cells release NA and A
chromaffin cells
describe the entire process of adrenaline synthesis
phenylalanine — tyrosine — L DOPA — Dopamine — Noradrenaline — adrenaline
what enzyme converts phenylalanine to tyrosine
phenylalanine hydroxylase
what enzyme converts tyrosine to L-DOPA
tyrosine hydroxylase
what enzyme converts L-DOPA to dopamine
DDC
what enzyme converts dopamine to noradrenaline
dopamine B hydroxylase
what enzyme converts noradrenaline to adrenaline
PNMT
where does synthesis of the catecholamines (dopamine/NA/A) occur?
adrenal medulla
postganglionic SNS neurons
where can drugs act in the synthesis of catecholamines and give examples
inhibit tyrosine hydroxylase
by a-methyl-P-tyrosine
carbidopa inhibit DDC (L-DOPA - dopamine)
where is dopamine converted to NA/A
in vesicles
what is VMAT and what does it do
vesicular monoamine transporter
packages free NA/dopamine in presynaptic membrane into vesicles
what does reserpine do?
blocks VMAT
leads NT being broken down
leads to block of SNS transmission
what does guanethidine do
prevents catecholamine exocytosis