Pharmacology of the Autonomic Nervous System I - Adrenergic Drugs Flashcards
How are the autonomic NS and somatic NS different in terms of connectivity to CNS?
Autonomic NS: Between CNS and organ there is one preganglionic neuron and one postganglionic neuron.
Somatic NS is a single motor neuron.
What is the primary role of the autonomic NS?
Maintains homeostasis through:
CO
Digestion
Blood flow
What is the primary role of the somatic NS?
Voluntary control
What type of receptors does acetylcholine bind to?
Nicotinic cholinocepter (within the ganglia)
Muscarinic cholinocepter (within the target tissue)
What neurotransmitter do sympathetic preganglionic nerves produce in paravertebral ganglia?
Acetylcholine
What is the name of the postganglionic nerve of the sympathetic NS?
Adrenergic nerve
Do all sympathetic nerves go to paravertebral ganglia?
No some go to the adrenal medulla and release acetylcholine which results in the adrenal medulla releasing adrenaline and noradrenaline.
What type of drugs are targeted by ANS drugs?
Muscarinic cholinoceptors or adrenoceptors on effector cells.
What occurs if neurotransmission is blocked at the ganglia?
Acting or blocking neurotransmission at ganglia produce complex and widespread changes that can be dangerous.
How is the autonomic NS organised so that it can produce desired effect when required?
It contains a chain of varicosities (swellings) with neurotransmitters inside them and they are released as the AP passes them in the neuron.
What do sympathetic postganglionic nerves release at the target tissue?
Most release NorAdrenaline (they are known as adrenergic nerves)
Several release Acetylcholine (several sympathetic postganglionic nerves are cholinergic)
What do parasympathetic postganglionic neurons release at target tissue?
Acetylcholine only (they are known as cholinergic nerves)
Example of cholinergic sympathetic nerves:
Sweat gland innervating nerves
What are the 2 major families of cholinoceptors and where are they found?
Nicotinic receptors (these are found in ganglia and are what triggers action potential in post ganglionic nerves)
Muscarinic (found on target tissues and are of 3 classes)
What are the classes of muscarinic receptors?
M1 (nerve cell body)
M2 (heart to decrease heart rate)
M3 (smooth muscle and glands)
There are 5 of these but the important ones to know are M2 and M3.
What are the major families of adrenoceptors?
Alpha (alpha1 and alpha2)
Beta (beta1 and beta2)
Where are the alpha receptors located and what do they do?
Alpha 1 receptors on vascular smooth muscle which cause them to contract in peripheral tissue.
Alpha 2 receptors are located on nerve varicosities.
Where are the beta receptors located and what do they do?
Beta1 receptors are located on the heart and increase its contractility and rate.
Beta2 receptors stimulate smooth muscle to dilate (relax) in the ariways.
Beta3 receptors act on fat