Autonomic Nervous System

Pharmacology

What is the substrate for acetylcholine (Ach) synthesis and how is it removed?

The substrate for acetylcholine synthesis is acetyl-CoA and choline; it is removed by the enzyme acetylcholinesterase.

What are the key types of nicotinic receptors and what types of receptors are they?

Key types of nicotinic receptors include N1 (neuromuscular junction) and N2 (autonomic ganglia); they are ligand-gated ion channels.

What are the key types of muscarinic receptors and what types of receptors are they?

Key types of muscarinic receptors include M1, M2, M3, M4, and M5; they are G-protein coupled receptors.

What is the substrate for catecholaminergic synthesis and what is the rate-limiting enzyme?

The substrate for catecholaminergic synthesis is tyrosine; the rate-limiting enzyme is tyrosine hydroxylase, which is regulated by feedback inhibition.

What neurotransmitters are catecholamines and what receptors do they act upon?

Catecholamines include dopamine, norepinephrine, and epinephrine; they act upon adrenergic receptors.

What factors determine if the signal at the synapse is passed on to the next cell?

Factors include neurotransmitter release, receptor activation, and the presence of inhibitory or excitatory signals.

What is the basic anatomic structure of the autonomic nervous system (ANS)?

The ANS consists of the sympathetic and parasympathetic divisions, each with pre-ganglionic and post-ganglionic neurons.

What neurotransmitter is released in the ganglionic synapses of the autonomic nervous system and what receptor does it act on?

Acetylcholine is released in ganglionic synapses and acts on nicotinic receptors.

What is the primary neurotransmitter released for voluntary skeletal muscle movement and what receptor does it act on?

The primary neurotransmitter is acetylcholine, which acts on nicotinic receptors at the neuromuscular junction.

Which component of the autonomic nervous system has long pre-ganglionic and short post-ganglionic fibers, and which has short pre-ganglionic and long post-ganglionic fibers?

The parasympathetic nervous system has long pre-ganglionic and short post-ganglionic fibers; the sympathetic nervous system has short pre-ganglionic and long post-ganglionic fibers.

What neurotransmitters are released by post-ganglionic nerve fibers in the ANS?

Post-ganglionic fibers release acetylcholine (in the parasympathetic system) or norepinephrine (in the sympathetic system).

To what receptor does acetylcholine bind in the ganglia of the autonomic nervous system?

Acetylcholine binds to nicotinic receptors in the ganglia.

What differences exist between the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) regarding origin and connections?

The SNS originates from the thoracolumbar region and has short pre-ganglionic fibers; the PNS originates from the craniosacral region and has long pre-ganglionic fibers.

What receptors are located on the effector cells of the PNS and SNS?

PNS effector cells have muscarinic receptors; SNS effector cells have adrenergic receptors.

Where is the primary location of Beta1 receptors and what is their effect?

Beta1 receptors are primarily located in the heart; their activation increases heart rate and contractility.

Where is the primary location of Beta2 receptors and what is their effect?

Beta2 receptors are primarily located in the lungs and blood vessels; their activation causes bronchodilation and vasodilation.

Where is the primary location of Beta3 receptors and what is their effect?

Beta3 receptors are primarily located in adipose tissue; their activation promotes lipolysis.

Where is the primary location of Alpha1 receptors and what is their effect?

Alpha1 receptors are primarily located in blood vessels; their activation causes vasoconstriction.

Where is the primary location of Alpha2 receptors and what is their effect?

Alpha2 receptors are primarily located presynaptically in the CNS; their activation inhibits norepinephrine release.

What is the mechanism when nicotinic receptors are activated?

Activation of nicotinic receptors leads to the opening of ion channels, resulting in depolarization of the postsynaptic cell.

What is the mechanism when muscarinic receptors are activated?

Activation of muscarinic receptors typically involves G-protein signaling pathways that can open or close ion channels and activate second messengers.

What is the mechanism when beta receptors are activated?

Activation of beta receptors leads to G-protein signaling that increases cAMP levels, resulting in various physiological effects.

What are some key sites of autonomic tone for the SNS and PNS?

Key sites include the heart, lungs, and digestive system, where SNS generally increases activity and PNS decreases it.

Which part of the ANS is responsible for sweating and what receptors are involved?

The sympathetic nervous system is responsible for sweating, primarily acting through muscarinic receptors.

What neurotransmitter is released in the adrenal medulla in response to activation of the N2 or NN receptor and what are the physiological effects?

Epinephrine is released from the adrenal medulla, leading to increased heart rate, blood pressure, and energy mobilization.

What higher centers regulate the autonomic nervous system and what are some examples of local autonomic reflexes?

Higher centers include the hypothalamus and brainstem; local reflexes include baroreceptor reflexes and gastrointestinal reflexes.

What is the enzyme that breaks down acetylcholine and what effect does donepezil have on its action?

The enzyme is acetylcholinesterase; donepezil inhibits this enzyme, prolonging the action of acetylcholine.

What are the two primary actions of post-synaptic receptors?

The two primary actions are excitatory (promoting depolarization) and inhibitory (promoting hyperpolarization).

A cholinergic drug with significant skeletal muscle side effects likely exerts its actions on what receptor?

It likely exerts its actions on nicotinic receptors at the neuromuscular junction.

An agonist at which receptor will lead to arteriolar constriction?

An agonist at Alpha1 receptors will lead to arteriolar constriction.

An agonist at which receptor will lead to arteriolar and smooth muscle relaxation?

An agonist at Beta2 receptors will lead to arteriolar and smooth muscle relaxation.

Which cholinoreceptors are ligand-gated channels?

Nicotinic receptors are ligand-gated channels.

What adrenoreceptor located presynaptically decreases norepinephrine release?

Alpha2 adrenoreceptors located presynaptically decrease norepinephrine release.

What receptor agonist in the heart would accelerate heart rate?

An agonist to beta-1 adrenergic receptors.

Which autonomic nervous system causes mydriasis (dilation of pupils)?

The sympathetic nervous system.

Which autonomic nervous system causes miosis (pin-point pupils)?

The parasympathetic nervous system.

What adrenergic receptor subtype is found in bronchiolar smooth muscle?

Beta-2 adrenergic receptors.

What is the action of an agonist at beta-2 adrenergic receptors in bronchiolar smooth muscle?

It causes bronchodilation.

Where are dopamine receptors primarily located?

In the central nervous system and renal vasculature.

What muscarinic receptors are present in the GI tract?

M2 and M3 muscarinic receptors.

What is the action of muscarinic receptors on the walls and sphincters of the GI tract?

They increase motility and secretion.

Does Spiriva® have muscarinic or anti-muscarinic actions?

It has anti-muscarinic actions.

What receptor does Lopressor® act on to slow heart rate?

Beta-1 adrenergic receptors.

Is Lopressor® an agonist or antagonist at beta-1 adrenergic receptors?

It is an antagonist.

What receptor does Timolol act on to decrease aqueous humor production?

Beta-1 adrenergic receptors.

Is Timolol an agonist or antagonist at that receptor?

It is an antagonist.

How does Oxybutynin ER help with urinary incontinence?

It reduces bladder contractions by blocking muscarinic receptors.

To what class of receptor does norepinephrine bind?

Adrenergic receptors.

What are the 5 primary receptor subtypes within the adrenergic receptor class?

Alpha-1, Alpha-2, Beta-1, Beta-2, and Beta-3.

From where does most parasympathetic outflow arise?

The brainstem and sacral spinal cord.

What is the purpose of autoreceptors?

To regulate neurotransmitter release and maintain homeostasis.

Which component of the autonomic nervous system elicits a more generalized response?

The sympathetic nervous system.

Which component of the central nervous system does not synapse at a ganglion?

The parasympathetic nervous system.

What adrenergic receptors are in the GI tract?

Alpha-1 and beta-2 adrenergic receptors.

What is the action of adrenergic receptors on the walls and sphincters of the GI tract?

They decrease motility and secretion.

What potential cardiac side effects might a patient experience from an anticholinergic drug?

Tachycardia and arrhythmias.

How does Albuterol (Beta-2 agonist) affect bronchiolar smooth muscles?

It causes relaxation and bronchodilation.

What type of property does Pilocarpine have that could cause night driving difficulties?

It has miosis-inducing properties, which can impair vision in low light.

What are the main neurotransmitters involved in the autonomic nervous system?

Dopamine (DA), Norepinephrine (NE), and Epinephrine.

What is the role of Tyrosine Hydroxylase in neurotransmitter synthesis?

It is involved in the conversion of L-tyrosine to L-DOPA, a precursor for dopamine.

How do norepinephrine and epinephrine interact with adrenergic receptors?

Norepinephrine acts on alpha1 via Gq, alpha2 via Gi, and beta1,2,3 via Gs; Epinephrine has similar actions.

What is the pathway from preganglionic to postganglionic neurons in the autonomic nervous system?

Preganglionic neuron → Autonomic ganglia → Postganglionic neuron → Effector.

What are the two main divisions of the autonomic nervous system?

Sympathetic and Parasympathetic.

What type of receptors does acetylcholine bind to in the autonomic nervous system?

Nicotinic receptors (N1 and N2) and Muscarinic receptors.

What is the primary effect of the sympathetic nervous system on the heart?

Increased heart rate and contractility.

What is the effect of the sympathetic nervous system on the lungs?

Smooth muscle relaxation leading to bronchodilation.

How does the sympathetic nervous system affect blood vessels?

It causes vasoconstriction and dilates pupils.

What is the role of acetylcholinesterase in neurotransmission?

It increases the duration of action of acetylcholine by breaking it down.

What are the effects of alpha1 and beta2 adrenergic receptors?

Alpha1 leads to sphincter contraction; Beta2 leads to smooth muscle relaxation (bronchodilation).

What is the function of autoreceptors in neurotransmitter regulation?

They provide negative feedback to regulate neurotransmitter release.

What is the significance of the vagus nerve in the autonomic nervous system?

It plays a crucial role in parasympathetic control of the heart and digestive tract.

What are the effects of pilocarpine as a parasympathomimetic?

It causes cholinergic side effects such as miosis and can lead to night blindness (nyctalopia).

How does the sympathetic nervous system differ from the somatic nervous system in terms of ganglia?

The somatic nervous system does not synapse at a ganglion, while the sympathetic nervous system may synapse on chromaffin cells of the adrenal medulla.

What is the primary action of beta1 antagonists?

They decrease heart rate and contractility.

What is the effect of alpha2 receptors on neurotransmitter release?

They presynaptically decrease norepinephrine release.

What is the role of the hypothalamus in the autonomic nervous system?

It integrates autonomic functions and regulates homeostasis.

What is the effect of the parasympathetic nervous system on the bladder?

It relaxes the bladder wall smooth muscle, decreasing urgency and frequency of urination.

What are the main receptors involved in the sympathetic nervous system?

Adrenoreceptors: alpha1, alpha2, beta1, beta2, beta3.

What is the effect of the sympathetic nervous system on the gastrointestinal tract?

It slows GI motility.

What is the general effect of dual innervation in the autonomic nervous system?

It allows for generally opposite effects on organs or tissues.