Exam 4 Flashcards
Sympathetic system
Two neurons
Short then long ganglion
Postganglion release NE and E
The sympathetic trunk ganglia innervates what
Thorax, abdomen, head, neck
The prevertebral ganglia innervates what
Organ below diaphragm
What is the percentage release of E and NE in sympathetic system and adrenal medulla
Sympathetic: 80% NE, 20% E
Adrenal Medulla: 20% NE, 80% E
What happens in the adrenal medulla
One neuron system
ACh is released by pregnaglion
Preganglion innervates chromaffin cells in medulla and release NE and E
(NE and E are hormones because they are in the circulation and not released at a synapse)
What are the presynaptic receptors in the sympathetic system and adrenal medulla
Both are nicotinic receptors (Nn)
For the adrenergic presynaptic receptors what do the auto receptors and hetero receptors do in respect to NE release
Auto receptors: inhibit and activate NE release
Hetero receptors: inhibit NE release
What are the two subgroups of the adrenergic receptors
Alpha and Beta
What does a2 receptor do
autoreceptor that inhibits of NE release
What does b2 receptor do
autoreceptor that facilitates of NE release
Heteroreceptors presynaptically
inhibit release of NE (M2, M4)
-DA receptor
-Histamine receptor
-Serotonin receptor
What is a1 receptor
Gq, PLC, increase IP3 DAG and Ca2+
What is a2 receptor
Gi, AC, decrease cAMP
What is b1, b2, and b3 receptor
Gs, AC, increase cAMP
E and NE in a1, a2, b1, b2, b3
a1: E > NE
a2: E = NE
b1: E = NE
b2: E > NE
b3: E < NE
Catecholamines
Involved in chemical transmission in the CNS and PNS
Dopamine (mesocortical neuron) -> NE (sympathetic postganglionic neurons) -> E (adrenal medulla)
Synthesis of catecholamines
hydroxylation -> decarboxylation -> hydroxylation -> methylation
Enzyme locations of catecholamines
DBM in secretory vesicles
Enzymes and primary product of dopaminergic neurons
Product: Dopamine
Little or no DBM and PNMT
Enzymes and primary product of adrenergic neurons
product: NE
Less PNMT than DBM
Enzymes and primary product of adrenal medulla
E (80%) NE (20%)
DBM and PNMT present
What drugs inhibit CA synthesis
alpha-methyltyrosine (inhibit tyrosine hydroxylase, treat pheochromocytoma)
carbidopa (increases DOPA, treatment of parkinsonism)
What drugs inhibit CA storage
reserpine (inhibit VMAT, antihypertensive drug)
tetrabenazine (inhibit VMAT, hyperkinetic disorders)
Inhibitor effects of VMAT mechanism
decrease NE storage -> decrease NE release
depletion of CA at synapse
NE accumulated in cytoplasm is degraded