Topic 3 Flashcards
two major NTs in efferent PNS
Acetylcholine and Catecholamines
Neurons that release ACh are called –
cholinergic neurons
receptors sensitive to ACh
cholinergic receptors
where is ACh released?
SNS neuromuscular junction (skeletal muscle), in both the sympathetic and parasympathetic ganglia, and from the parasympathetic postganglionic neurons
examples of catecholamines
epinephrine and nor-epinephrine
Neurons that release catecholamines
adrenergic neurons
receptors sensitive to catecholamines
adrenergic receptors
What releases Epinephrine (AKA adrenalin)?
adrenal medulla
What releases Nor-epinephrine?
sympathetic postganglionic neurons.
agonists mimic normal neurotransmitter function to –
activate downstream signal transduction pathways.
What is the function of antagonists?
compete with and block normal neurotransmitter function
What is almost always an antagonist?
anesthetics
What is capable to use all receptor types?
smooth muscle
In smooth muscle, what is the possible effect of one NT in one cell?
multiple actions
What receptor is common in cardiac muscle?
G-protein coupled receptors
Why doesn’t the transmitter molecule need to enter the cell to be amplified when using a G-protein coupled receptor?
produces intracellular second messengers
examples of intracellular second messengers
like cyclic AMP, inositol trisphosphate (IP3) or diacylglycerol (DAG)
What are two main classes of cholinergic receptors?
Nicotinic and Muscarinic
What is Nicotinic class of receptors particularly sensitive to?
ACh and plant alkaloid nicotine
What is Muscarinic class of receptors is particularly sensitive to?
ACh and the mushroom poison muscarine
describe response of alpha adrenergic receptors
NE > E»_space;> I (synthetic catecholamine isoproterenol)
describe response of beta adrenergic receptors
I > E > NE
What comprises the major adrenergic receptor subtype in most effector tissues?
alpha-1 receptors
alpha-1 receptors comprise – of the receptors in the heart
only 0.2%
where are alpha-2 receptors mainly found?
on pre-junctional nerve cells
what is the function of alpha-2 receptors?
inhibit neurotransmitter release
where is beta-1 receptors mainly found?
heart
where is beta-2 receptors mainly found?
arterioles and coronary vasculature
The effects of sympathetic stimulation depends on what?
receptor type
target organ
concentration and distribution
