Parasympathetic and Sympathetic Nervous Systems: Receptors and Neurotransmitters

A comprehensive set of flashcards focused on the key concepts related to the parasympathetic and sympathetic nervous systems, including their organization, physiological functions, neurotransmitters, and receptor types.

What is the primary neurotransmitter of the parasympathetic nervous system?

Acetylcholine (ACh)

What type of receptors are involved in parasympathetic signaling?

Muscarinic and Nicotinic receptors.

What does the parasympathetic nervous system primarily regulate?

Rest and digest functions, maintaining homeostasis.

Where do preganglionic neurons of the parasympathetic nervous system originate?

In the nuclei within the CNS - brain stem and sacral spinal cord.

What type of signaling is characterized by cholinergic signaling?

Neurotransmitter: Acetylcholine; Termination: Acetylcholinesterase.

What is the difference between nicotinic and muscarinic receptors?

Nicotinic receptors are ion channels, while muscarinic receptors are G-protein coupled receptors.

Which muscarinic receptor subtype is found in the heart?

M2 receptor.

What physiological effect does M2 receptor activation have on the heart?

Slows the heart rate.

Which receptors are targeted by cholinergic agonists?

Muscarinic receptors.

What action occurs when nicotine binds to nicotinic receptors?

Stimulates autonomic ganglia and neuromuscular junction.

What is a key feature of sympathetic nervous system signaling?

Involves norepinephrine (NE) and epinephrine (E).

What differentiates the sympathetic nervous system from the parasympathetic?

Sympathetic is associated with 'fight or flight' responses.

Where do preganglionic neurons of the sympathetic nervous system originate?

Thoracic and lumbar regions of the spinal cord.

What type of adrenergic receptor is primarily responsible for vasodilation?

Beta-2 adrenergic receptors.

What receptor do alpha-1 adrenergic agonists primarily target?

Alpha-1 adrenergic receptors.

What physiological response does alpha-1 receptor activation cause?

Vasoconstriction.

How do beta-blockers affect heart rate?

They decrease heart rate and myocardial contractility.

What is the mechanism of action of atropine?

It blocks the effects of acetylcholine on muscarinic receptors.

What is the clinical use of pilocarpine?

To treat dry mouth and to reduce intraocular pressure.

Which receptor subtype promotes urinary voiding?

M3 receptor.

What is the primary function of acetylcholinesterase?

To terminate cholinergic signaling by breaking down acetylcholine.

What effect does myasthenia gravis have on the body?

Weakness due to an autoimmune response against nicotinic receptors.

What condition can lead to cholinergic crisis?

Overdose of cholinergic medications or organophosphate poisoning.

What neurotransmitter is involved in adrenergic signaling?

Norepinephrine.

What is the role of D2 receptors in the autonomic nervous system?

They inhibit adenylate cyclase, leading to reduced cAMP.

What is the significance of receptor desensitization?

Receptors become less responsive to agonists over time.

What are the effects of sympathetic activation on blood vessels?

Constriction of some blood vessels and dilation of others.

What is a characteristic of antimuscarinic drugs?

They block the action of acetylcholine at muscarinic receptors.

What type of drug is scopolamine?

An antimuscarinic agent used for motion sickness.

How does norepinephrine affect blood pressure?

It increases blood pressure through vasoconstriction.

What is a direct-acting cholinergic agonist example?

Bethanechol.

What effect do adrenergic antagonists have on the body?

They block the effects of norepinephrine and epinephrine.

Which neurotransmitter is primarily associated with adrenal medulla signaling?

Epinephrine.

What physiological function does the M3 muscarinic receptor have in the lungs?

Bronchoconstriction and increased secretions.

What happens when acetylcholine binds to M2 receptors in the heart?

It causes hyperpolarization and decreased heart rate.

What are the primary roles of adrenergic receptors?

To mediate the 'fight or flight' response.

What therapeutic use does donepezil serve?

It is used in the treatment of Alzheimer’s disease.

What is the role of ganglionic blockers?

They inhibit both parasympathetic and sympathetic signaling.

What does a beta-adrenergic agonist do?

It stimulates beta receptors, leading to various physiological effects.

How are drugs classified according to their action on receptors?

As antagonists, agonists, partial agonists, or inverse agonists.

What is the action of dopamine on renal blood flow?

Dopamine causes vasodilation to increase blood flow to the kidneys.

What effect does increased intracellular calcium have in muscle contraction?

It promotes muscle contraction via myosin light chain kinase.

What is one consequence of cholinergic toxicity?

Excess salivation and secretions.

What is the significance of presynaptic alpha-2 adrenergic receptors?

They inhibit norepinephrine release.

What physiological crisis occurs due to excessive cholinergic signaling?

Cholinergic Crisis.

Which muscarinic receptor subtype is involved in glandular secretion?

M3 receptor.

What is the terminal mechanism for norepinephrine signaling?

Reuptake or enzymatic metabolism.

What does stimulation of beta-1 receptors lead to in the heart?

Increased heart rate and contractility.

What physiological outcomes result from parasympathetic stimulation of GI tract receptors?

Increased secretory and motor activity.

What denotes sympathetic nervous system signaling?

Increased energy expenditure and blood flow to muscles.

How does excess norepinephrine impact vascular resistance?

It generally leads to increased vascular resistance and blood pressure.

What is the physiological effect of M2 receptor activation in the heart?

Decreased heart rate.

What changes occur in the body during 'fight or flight' responses?

Increased heart rate, redistribution of blood flow, and increased energy availability.

What role does calcium play in adrenergic signaling?

It promotes muscle contraction and neurotransmitter release.

What is the primary action of cholinergic agonists?

To enhance effects of acetylcholine.

What physiological actions are mediated by β2-adrenergic receptors?

Bronchodilation and vasodilation in skeletal muscle.

What are the primary functions of cholinergic signaling in the body?

Regulating gastric secretion, heart rate, and smooth muscle contraction.

What is the role of adrenergic antagonists?

They block adrenergic signaling, reducing sympathetic effects.

What receptor subtypes have a role in lowering heart rate?

M2 muscarinic receptors.

What is vasodilation and which receptor mediates this response?

Relaxation of blood vessels, mediated by β2 adrenergic receptors.

What is the effect of alpha-1 receptor activation on blood vessels?

Constriction leading to increased blood pressure.

What is the relationship between norepinephrine and heart rate?

Norepinephrine increases heart rate through β1 receptor activation.

What outcome results from increased activity of acetylcholinesterase?

Decreased levels of acetylcholine, leading to less cholinergic activity.

What is the primary mechanism of action for clonidine?

Stimulates alpha-2 receptors, reducing norepinephrine release.

What direct action does phenylephrine have on the body?

It constricts blood vessels, increasing blood pressure.

What is the consequence of blocking muscarinic receptors with atropine?

It leads to increased heart rate and reduced secretions.

What pharmacological effect can occur with a cholinergic crisis?

Pupillary constriction and excessive salivation.

What is the function of G-protein coupled receptors in the autonomic nervous system?

They transduce signals from neurotransmitters to elicit cellular responses.

What neurotransmitter does the sympathetic nervous system predominantly rely on?

Norepinephrine (NE).

What cascade does M3 receptor activation initiate in smooth muscles?

Phospholipase C pathway leading to increased intracellular calcium.

How do antimuscarinic agents affect bronchial smooth muscle?

They cause relaxation, leading to bronchodilation.

What physiological response occurs from parasympathetic activation in the digestive system?

Increased digestion and motility.

Why are receptor polymorphisms significant?

They can influence drug efficacy and individual responses to treatments.

What are the two major subsystems of the autonomic nervous system?

Parasympathetic and sympathetic nervous systems.

What is the role of adrenergic receptors in the fight-or-flight response?

They prepare the body for physical exertion and stress.

What type of receptors does epinephrine act upon systemically?

Alpha and beta adrenergic receptors.

What is the end effect of cholinergic agonists like bethanechol?

Stimulates bladder contraction for urinary voiding.

What are the potential outcomes of excessive adrenergic receptor stimulation?

Hypertension, anxiety, and tachycardia.

What is the significance of β2 adrenergic agonists in asthma treatment?

They relax bronchial smooth muscles, improving airflow.

What are the clinical implications of alpha-2 agonists like clonidine?

They can reduce blood pressure and manage ADHD.

What role does the vagus nerve play in the parasympathetic nervous system?

It carries parasympathetic signals to various organs, especially the heart.

How does sympathetic activation alter lung function?

It relaxes bronchial muscles and dilates airways.

What is the therapeutic effect of atropine in overdose situations?

It counters excessive parasympathetic activity.

What type of drug is propranolol and what does it treat?

It is a non-selective beta-blocker used for hypertension and anxiety.

What physiological change occurs with increased cAMP levels?

Enhanced heart contractility and rate.

What is the expected physiological effect of organophosphate poisoning?

Excessive cholinergic signaling and symptoms of cholinergic crisis.

What are the central effects of beta blockers?

They lower heart rate and reduce myocardial oxygen demand.

What is the physiological function of M1 receptors in the CNS?

They mediate neurotransmission and cognitive function.

How do cholinesterase inhibitors work therapeutically?

They increase the availability of acetylcholine at synapses.

What are the central autonomic functions regulated by the vagus nerve?

Heart rate, digestion, and respiratory rate.

How do α1 adrenergic antagonists function in hypertension treatment?

They relax vascular smooth muscles, lowering blood pressure.

What effect does norepinephrine have on cardiac output?

It increases cardiac output through β1 receptor activation.

What receptor subtype is associated with reduced contraction in the heart?

M2 muscarinic receptor.

What triggers the release of norepinephrine from adrenergic neurons?

Calcium influx during an action potential.

How does adrenaline influence liver metabolism?

It enhances glycogenolysis, increasing glucose availability.

What can happen if the sympathetic nervous system is overactive?

It can result in sustained high blood pressure and other stress-related issues.

What happens to blood vessels in response to sympathetic activation?

Some constrict, while others dilate depending on adrenergic receptor subtype.

What is meant by the term 'rest and digest' concerning the parasympathetic system?

It refers to the body's processing of food and energy conservation.

What are the potential effects of blocking adrenergic receptors?

They may lead to reduced heart rate and lower blood pressure.

How does exercise influence sympathetic nervous system activity?

It increases sympathetic outflow, leading to heightened alertness and physical readiness.