Autonomic nervous system Flashcards
Where are nicotinic ACh receptors
- Neuromuscular junction
- Sympathetic ganglia
- Parasympathetic ganglia
- Central nervous system
Where are the muscarinic Ach receptor
- Parasympathetic target organs
- Sweat glands
- Vascular smooth muscle
- Central nervous system
What are the main locations of the M1 muscarinic receptor?
Autonomic ganglia
Glands: gastric, salivary, lacrimal
What is the cellular response of M1 receptors
Increases IP3 and DAG
What is the functional response of M1 receptors?
Gastric secretion
What is the location of M2 receptors?
Heart: atria
What is the cellular response of M2 receptor?
Decreases cAMP
What is the functional response of M2 receptors?
Cardiac inhibition
What is the location of the M3 receptor?
Exocrine glands: gastric, salivary, etc.
Smooth muscle: GI tract, eye, airways, bladder
Blood vessels: endothelium
What is the cellular response of the M3 receptor?
increase IP3 and DAG
What is the functional response of the M3 receptor?
Gastric, salivary secretion
GI smooth muscle contraction
Ocular accommodation
Vasodilation
What G protein is associated with muscarinic receptors?
- Gq - M1 and M3 -
- Gi - M2
What are the Non- selective muscarinic agonists?
- Pilocarpine
- Bethanechol
What are the clinical uses of Pilocarpine
- Constriction of pupils
- Glaucoma to decrease intraocular pressure
- Xerostomia
What are the clinical uses of Bethanechol?
- Clinical uses
- Bladder and gastrointestinal hypotonia
List the muscarinic Ach receptor antagonists
- Atropine
-Glucopyrronium - Hyoscine hydrobromide
- Hyoscine butylbromide
- Ipratropium
-Tropicamide
What are the pharmacological properties of atropine and glycopyrronium?
Non-selective antagonist
Well absorbed orally
CNS effects
What are the clinical uses of atropine and glycopyrronium?
Adjunct for anaesthesia
Anticholinesterase poisoning
Bradycardia
What are thee pharmacological properties of hyoscine hydrobromide?
Non-selective antagonist
Well absorbed orally
CNS effects
What are the clinical uses of hyoscine hydrobromide?
- Hypersalivation
- Motion sickness
What are the pharmacological properties of hyoscine butylbromide?
Non-selective antagonist
Poorly absorbed orally
CNS effects
What are the clinical uses of Hyoscine butylbromide?
Gastrointestinal spasms
What are the pharmacological properties of Ipratropium?
Delivered via inhaler or nebuliser
Does not cross blood brain barrier
What are the clinical uses of Ipratropium?
Maintenance treatment of COPD
What are the pharmacological properties of tropicamide?
Non-selective antagonist
Well absorbed orally
CNS effects
shorter acting
What are the clinical uses of tropicamide?
Ophthalmic use (mydriasis)
What type of neurons are responsible for noradrenergic transmission?
Adrenergic neurons
What are the main neurotransmitters involved in noradrenergic transmission?
Dopamine, Adrenaline, Noradrenaline
What is the rate limiting step in catecholamine synthesis?
Tyrosine hydroxylase
What inhibits tyrosine hydroxylase?
Catecholamines
What is the function of DOPA decarboxylase in catecholamine synthesis?
Converts DOPA to dopamine
What is methyldopa used for?
Hypertension in pregnancy
Where is dopamine β-hydroxylase (DBH) located?
Membrane bound
What hormone induces phenylethanolamine N-methyltransferase (PNMT)?
Adrenal cortex hormones
How is noradrenaline (NA) release facilitated?
By Ca2+ influx
What role do α2 adrenoreceptors play in noradrenaline release?
They decrease Ca2+ influx, thus decreasing NA release
What percentage of norepinephrine is recaptured by neurons?
~75%
What is the name of the transporter responsible for norepinephrine reuptake?
Norepinephrine transporter (NET)
What does the vesicular monoamine transporter (VMAT) do?
Repackages norepinephrine
What are indirectly acting sympathomimetic drugs?
Drugs that affect catecholamine release or uptake
Name an example of an indirectly acting sympathomimetic drug.
Amphetamines
What is the primary effect of drugs that act on α2 adrenoreceptors?
Inhibition of catecholamine release
What type of drugs inhibit catecholamine uptake?
NET inhibitors
Name a drug that is a monoamine oxidase (MAO) inhibitor.
Used in depression
What is the primary function of the sympathetic nervous system?
Control ‘fight or flight’ responses
Which adrenergic receptor subtype is responsible for vasoconstriction?
α1
What is the effect of β1 receptors on the heart?
Increase heart rate and force
What is the role of β2 receptors in the lungs?
Bronchodilation
What does adrenaline do during anaphylaxis?
Vasoconstriction, ↑ heart rate, bronchodilation, ↓ histamine release
What is prazosin used for?
Benign prostatic hyperplasia
What is the mechanism of action of tamsulosin?
More prostate-specific antagonist of α1 receptors
What are the two main groups of adrenoreceptors?
α and β adrenoreceptors
What are the key learning outcomes related to noradrenaline?
Understand effects on synthesis, release, agonists, and antagonists
True or False: Agonists of one system may have the same effect as antagonists of another.
True
Fill in the blank: α1, α2, β1, β2, and β3 are subtypes of _______.
adrenoreceptors
