L23, 24 Sympathetic and Parasympathetic pharmacology Flashcards
What are the two types of neurons found in the autonomic nervous system?
Cholinergic neurons and adrenergic neurons.
Where do sympathetic neurons originate in the spinal cord?
Sympathetic neurons arise from the thoracic and lumbar regions of the spinal cord.
What are the two types of neurons found in the autonomic nervous system?
Cholinergic neurons and adrenergic neurons.
Where do sympathetic neurons arise from in the spinal cord?
Sympathetic neurons arise from the thoracic and lumbar regions of the spinal cord.
What is the primary function of the sympathetic nervous system?
The sympathetic nervous system is responsible for the fight-or-flight response.
What type of receptors are found on postganglionic neurons in both the sympathetic and parasympathetic systems?
Both systems have nicotinic receptors on their postganglionic neurons.
What are the primary functions of the parasympathetic nervous system?
The parasympathetic nervous system promotes functions such as pupil constriction, salivation, airway constriction, slowing of the heartbeat, digestion stimulation, glucose uptake, intestinal activity, urinary bladder contraction, and erection.
How does the sympathetic nervous system affect digestion?
The sympathetic nervous system inhibits digestion.
What type of receptors are found on postganglionic neurons in both the sympathetic and parasympathetic systems?
Both systems have nicotinic receptors on their postganglionic neurons.
What type of receptors do parasympathetic neurons stimulate in the eye to cause pupil constriction?
Muscarinic receptors
What is the effect of sympathetic adrenergic neurons on the pupils?
Pupil dilation
What are the two types of neurons that innervate organs in the autonomic nervous system?
Sympathetic and parasympathetic neurons.
How does the autonomic nervous system respond to different situations?
It dynamically shifts between sympathetic and parasympathetic dominance.
How many cranial and spinal nerves are part of the peripheral nervous system?
There are 12 cranial nerves and 31 pairs of spinal nerves.
How do the sympathetic and parasympathetic nervous systems differ in terms of their origin in the body?
The sympathetic nervous system originates from certain parts of the spinal cord, while the parasympathetic nervous system originates from the brain stem.
What neurotransmitter is released by cholinergic fibers in the sympathetic nervous system?
Acetylcholine
Which type of fibers are responsible for releasing dopamine to stimulate the renal vessels in the sympathetic nervous system?
Dopaminergic fibers
What neurotransmitters are released by the adrenal medulla during sympathetic activation?
Adrenaline and Noradrenaline
What role does acetylcholine play in the sympathetic nervous system response?
It stimulates the adrenal glands directly without going through ganglia.
What physiological changes occur in the body during a stress response mediated by the sympathetic nervous system?
Increased heart rate, bronchodilation, decreased saliva production, and increased blood sugar levels.
How does the parasympathetic nervous system counteract the effects of the sympathetic nervous system?
It promotes relaxation, digestion, and recovery by reversing the stress-induced changes.
What is the role of beta agonist drugs in the context of the sympathetic nervous system?
They mimic sympathetic activation, causing effects like bronchodilation and increased heart rate.
What is the primary neurotransmitter released by the parasympathetic nervous system?
Acetylcholine
What are the effects of parasympathetic stimulation on heart rate and gastrointestinal activity?
Heart rate decreases and gastrointestinal activity increases.
What is the primary effect of noradrenaline on the body?
It increases blood pressure by stimulating alpha and beta receptors.
What are the common side effects of medications that stimulate the sympathetic nervous system?
Increased heart rate, elevated blood glucose, nervousness, and dry mucous membranes.
What types of respiratory conditions are treated with beta-agonist medications like salbutanol?
Conditions such as COPD and asthma.
What is the primary effect of beta blockers on the sympathetic nervous system?
Beta blockers decrease heart rate and blood pressure by inhibiting sympathetic responses.
What are the potential side effects of non-selective beta blockers in patients with asthma?
Non-selective beta blockers can cause bronchoconstriction, worsening asthma symptoms.
It does this by blocking beta-2 receptors in the lungs, leading to bronchoconstriction, which is particularly dangerous for patients with asthma.
What is the role of anticholinergic drugs in the context of the parasympathetic nervous system?
Anticholinergic drugs inhibit the release of acetylcholine, leading to sympathetic-like effects.
What is the role of anticholinergic bronchodilators in respiratory treatment?
They dilate the respiratory system to alleviate bronchoconstriction.
What drug is commonly used to increase heart rate in cases of severe bradycardia?
Atropine.
How do anticholinergic drugs affect pupil size?
They dilate the pupils.
What are the primary neurotransmitters of the SNS?
Acetylcholine (ACh) at ganglia and noradrenaline (NAd) at postganglionic synapses.
What type of receptor is targeted at the ganglionic synapse in the SNS?
Nicotinic acetylcholine receptors (nAChRs).
Name the five adrenergic receptor subtypes and their primary functions.
- α1: Vasoconstriction.
- α2: Presynaptic inhibition of neurotransmitter release.
- β1: Increases heart rate and contractility.
- β2: Bronchodilation and vasodilation.
- β3: Bladder relaxation and lipolysis.
What is the primary use of β2-agonists like salbutamol?
To treat asthma by inducing bronchodilation.
What is an example of an α1-antagonist and its use?
Prazosin, used for hypertension.
What is the mechanism of action for adrenergic agonists?
They mimic the effects of catecholamines (e.g., noradrenaline) on adrenergic receptors.
What is the effect of β-blockers like propranolol?
Reduce heart rate, cardiac output, and manage hypertension.
What are MAO inhibitors used for, and what is a common adverse effect?
Used as antidepressants; adverse effect includes the “cheese reaction” (hypertensive crisis from tyramine ingestion).
How do drugs like amphetamine work as indirect sympathomimetics?
They displace noradrenaline from vesicles, increasing its release into the synapse.
What is the effect of drugs that inhibit noradrenaline transporters (NET), like cocaine?
They enhance sympathetic activity, causing increased heart rate and blood pressure.
What happens with prolonged exposure to adrenergic agonists?
Receptor desensitization, leading to reduced drug efficacy.
What adrenergic agonist is used for anaphylaxis, and why?
Adrenaline; it stimulates α and β receptors to cause vasoconstriction and bronchodilation.
Name a β1-selective antagonist and its application.
Atenolol, used for hypertension and cardiac arrhythmias.
What condition can β2-agonists delay besides asthma?
Premature labor, by relaxing uterine smooth muscle.
How does norepinephrine transporter (NET) terminate neurotransmitter action?
noradrenaline basically, US way of saying it
By reuptaking noradrenaline into the presynaptic neuron.
Which neurotransmitter is involved in preganglionic sympathetic transmission, and what receptor does it act on?
Acetylcholine (ACh), which acts on nicotinic acetylcholine receptors.
How do α2-adrenoceptors inhibit further neurotransmitter release?
By negative feedback, reducing noradrenaline release from presynaptic terminals.
What are the primary effects of β3-adrenoceptor activation?
Lipolysis in adipose tissue and bladder relaxation.
Which adrenergic receptor subtype is predominant in the heart, and what is its effect?
β1; increases heart rate (chronotropy) and contractility (inotropy).
What is hexamethonium used for, and how does it act?
It is a ganglionic blocker that inhibits nicotinic receptors, reducing autonomic activity.
What is the difference between Uptake 1 and Uptake 2 for noradrenaline?
Uptake 1: High-affinity neuronal uptake via NET.
Uptake 2: Low-affinity extraneuronal uptake into tissues.
Which drugs inhibit NET, and what are their effects?
Norepinephrine Transporter
Cocaine and tricyclic antidepressants; they enhance sympathetic activity, causing tachycardia and increased BP.
Outline the key steps in noradrenaline synthesis.
- Tyrosine → DOPA (via tyrosine hydroxylase).
- DOPA → Dopamine (via DOPA decarboxylase).
- Dopamine → Noradrenaline (via dopamine β-hydroxylase).
What is the role of MAO in neurotransmitter metabolism?
Monoamine Oxidase
MAO breaks down catecholamines (e.g., noradrenaline, dopamine), regulating their levels.
What condition are MAO inhibitors primarily used to treat?
Depression, by increasing levels of noradrenaline, dopamine, and serotonin.
Why are indirect sympathomimetics like amphetamine abused?
Due to their CNS effects, including euphoria, increased alertness, and enhanced energy.
What intracellular pathways do adrenergic receptors use?
α1: Phospholipase C-β activation → IP3/DAG pathway.
β1 and β2: Adenylyl cyclase activation → cAMP increase.
How does β2 activation cause vasodilation?
By increasing cAMP, which reduces intracellular calcium levels in smooth muscle.
Which drugs are used for cardiogenic shock, and how do they work?
Adrenaline and dobutamine; they stimulate β1 receptors to improve cardiac output.
How do β-blockers like timolol help in glaucoma?
By reducing aqueous humor production, lowering intraocular pressure.
Name common adverse effects of sympathomimetic drugs.
Tachycardia, hypertension, tremors, and anxiety.
What is the primary function of nicotinic receptors?
Nicotinic receptors are primarily involved in the activation of skeletal voluntary muscles at the neuromuscular junction.
What neurotransmitter is primarily associated with sympathetic and parasympathetic preganglionic fibers?
Acetylcholine
What type of receptors are found in the ganglia of the autonomic nervous system?
Nicotinic receptors
What type of receptors are found in the heart as part of the autonomic nervous system?
Muscarinic receptors
What is the adrenal medulla considered in the context of the autonomic nervous system?
A modified ganglion
What type of receptor is found at the neuromuscular junction for skeletal muscles?
Nicotinic receptors (N_m)
What neurotransmitter do preganglionic fibers secrete in the autonomic nervous system?
Acetylcholine (ACh)
What are the two types of receptors that acetylcholine can act on?
Nicotinic and Muscarinic receptors
What are the two main types of acetylcholine receptors and where are they found?
The two main types of acetylcholine receptors are nicotinic receptors and muscarinic receptors. Nicotinic receptors are found in the neuromuscular junction and ganglia, while muscarinic receptors are found in smooth and cardiac muscles.
How do G protein-coupled receptors (GPCRs) function in relation to muscarinic receptors?
Muscarinic receptors are G protein-coupled receptors (GPCRs) that transmit signals from water-soluble ligands outside the cell to intracellular enzymes, facilitating various cellular responses.
What is the role of Gq-coupled receptors in muscle contraction?
Gq-coupled receptors, such as M1, M3, and M5, stimulate contraction by increasing intracellular calcium levels.
How do Gi-coupled receptors affect cardiac function?
Gi-coupled receptors, like M2 and M4, inhibit cardiac function by decreasing cyclic AMP levels, leading to reduced heart rate and contractility.
What is the primary function of M3 muscarinic receptors in the lungs?
M3 receptors contract the bronchi and increase bronchial secretions.
Where are M1, M2, and M3 muscarinic receptors primarily located in the body?
M1 is in the brain, M2 is in the heart, and M3 is in various tissues including lungs and glands.
What are muscarinic antagonists and provide an example?
Muscarinic antagonists are drugs that block muscarinic receptors. An example is atropine.
What is the effect of neuromuscular blockers on muscle activity?
Neuromuscular blockers inhibit muscle contraction, leading to muscle relaxation.
What are the key differences between nicotinic and muscarinic receptors?
Nicotinic receptors are found in skeletal voluntary muscles at the neuromuscular junction (also called the motor end plate) s
Muscarinic receptors are located in peripheral tissues, including:
Heart
Eyes
GI tract s
What types of connections use MUSCARINIC receptors?
- Smooth muscles
- Cardiac muscles (heart)
- Organs/glands
Location reminder: Think “M” for organs that Move involuntarily!
What types of connections use NICOTINIC receptors?
- Neuron-to-neuron (in ganglia)
- Neuron-to-SKELETAL muscle (neuromuscular junction)
Location reminder: Think “N” for Neurons and skeletal muscles!
Name all the neurons and neurotransmitters in the PNS
Preganglionic Neurons:
Neurotransmitter: Acetylcholine (ACh)
Receptor: Nicotinic receptors on postganglionic neurons.
Postganglionic Neurons:
Neurotransmitter: Acetylcholine (ACh)
Receptor: Muscarinic receptors on target organs (rest-and-digest functions).
