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Questions and Answers
Which pharmacological action is directly associated with β1 stimulation in the heart?
Which pharmacological action is directly associated with β1 stimulation in the heart?
What effect does α1 stimulation have on urinary bladder function?
What effect does α1 stimulation have on urinary bladder function?
In which situation is it appropriate to use norepinephrine?
In which situation is it appropriate to use norepinephrine?
What is the main adverse effect associated with the administration of norepinephrine?
What is the main adverse effect associated with the administration of norepinephrine?
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Which of the following drugs is a selective β1 agonist?
Which of the following drugs is a selective β1 agonist?
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What is a primary therapeutic use of non-selective beta agonists like isoprenaline?
What is a primary therapeutic use of non-selective beta agonists like isoprenaline?
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What is the effect of β2 stimulation on bronchial passages?
What is the effect of β2 stimulation on bronchial passages?
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Which mechanism is involved in the action of α1 agonists used as topical decongestants?
Which mechanism is involved in the action of α1 agonists used as topical decongestants?
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Which medication is primarily used as a uterine relaxant to prevent preterm labor?
Which medication is primarily used as a uterine relaxant to prevent preterm labor?
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What is a common adverse effect associated with β2 agonists like salbutamol and terbutaline?
What is a common adverse effect associated with β2 agonists like salbutamol and terbutaline?
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Which statement is true regarding the pharmacological actions of mixed-acting sympathomimetics such as ephedrine?
Which statement is true regarding the pharmacological actions of mixed-acting sympathomimetics such as ephedrine?
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What effect does the acidification of urine have on the excretion of ephedrine?
What effect does the acidification of urine have on the excretion of ephedrine?
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What is a primary therapeutic use of amphetamine?
What is a primary therapeutic use of amphetamine?
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Which characteristic is associated with the phenomenon of tachyphylaxis in mixed-acting sympathomimetics?
Which characteristic is associated with the phenomenon of tachyphylaxis in mixed-acting sympathomimetics?
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What condition can ephedrine potentially exacerbate in elderly patients?
What condition can ephedrine potentially exacerbate in elderly patients?
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Which pharmacological action is NOT associated with β2 agonists?
Which pharmacological action is NOT associated with β2 agonists?
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What is the primary neurotransmitter released by the postganglionic sympathetic neurons?
What is the primary neurotransmitter released by the postganglionic sympathetic neurons?
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Which receptor type is primarily associated with vasodilation of skeletal muscle blood vessels?
Which receptor type is primarily associated with vasodilation of skeletal muscle blood vessels?
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How do catecholamines differ from non-catecholamines regarding metabolism?
How do catecholamines differ from non-catecholamines regarding metabolism?
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What physiological effect is associated with stimulation of β1 adrenoceptors?
What physiological effect is associated with stimulation of β1 adrenoceptors?
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What is the effect of α1 receptor stimulation on blood pressure?
What is the effect of α1 receptor stimulation on blood pressure?
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Which drug class would mimic the effects of epinephrine?
Which drug class would mimic the effects of epinephrine?
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What effect does epinephrine have on cardiac output?
What effect does epinephrine have on cardiac output?
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What is an effect associated with parasympathomimetics?
What is an effect associated with parasympathomimetics?
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Study Notes
Autonomic Nervous System
- The autonomic nervous system (ANS) is part of the peripheral nervous system
- It is divided into two branches: sympathetic and parasympathetic
- Sympathetic: "fight or flight" response
- Parasympathetic: "rest and digest" response
Sympathetic Nervous System
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Physiological Effects:
- Increased heart rate
- Increased blood pressure
- Dilation of pupils
- Bronchodilation
- Increased blood sugar
- Reduced digestion
- Increased sweating
- Stress response
- Origin: T1-L2 of the spinal cord
- Ganglia: Close to spinal cord; short preganglionic fibers
- Neurotransmitter: Acetylcholine (ACh) at ganglion, Norepinephrine (NE) at target organ
- Receptor types: Primarily adrenergic (α and β) receptors
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Anatomy:
- Most organs receive dual nerve supply, except some.
- Includes dilator pupillae M, erector pili M, adrenal medulla, sweat glands, ventricles, blood vessels
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Function:
- Activated in response to threatening stressors
- Mobilizes body resources for action
Parasympathetic Nervous System
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Physiological Effects:
- Decreased heart rate
- Decreased blood pressure
- Constriction of pupils
- Bronchoconstriction
- Increased digestion
- Increased urination
- Origin: Cranial nerves (III, VII, IX, X) and sacral spinal cord segments (S2-S4)
- Ganglia: Near or embedded in organs; long preganglionic fibers
- Neurotransmitter: Acetylcholine (ACh) at ganglion and target organ
- Receptor types: Primarily cholinergic (muscarinic and nicotinic) receptors.
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Anatomy:
- Near or embedded in organs
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Function:
- Activates relaxation response
Neurotransmitters
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Sympathetic:
- Ganglia: Acetylcholine (ACh)
- Postganglionic: Norepinephrine (NE)
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Parasympathetic:
- Ganglia: Acetylcholine (ACh)
- Postganglionic: Acetylcholine (ACh)
Receptors
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Autonomic receptors - cholinergic and adrenergic
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Cholinergic receptors - respond to acetylcholine
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Adrenergic receptors - respond to norepinephrine and epinephrine
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α1 and α2: primarily vasoconstriction
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β1: Primarily cardiac stimulation
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β2: Primarily bronchodilation, relaxation of smooth muscles, uterus
Physiology (Sympathetic and Parasympathetic)
- Tone: The basal level of activity in the system
- Blood vessels: Sympathetic: vasoconstriction; Parasympathetic: no direct innervation
- Heart: Sympathetic: increased rate and contractility; Parasympathetic: decreased rate
- Blood pressure: Sympathetic: increased; Parasympathetic: decreased
- Eye: Sympathetic: mydriasis; Parasympathetic: miosis
- Bronchi: Sympathetic: bronchodilation; Parasympathetic: bronchoconstriction
- GIT, urinary tract: Sympathetic: inhibits tone and motility, contracts sphincter; Parasympathetic: increases tone and motility, relaxes sphincters
- Urinary bladder: Sympathetic: contracts sphincter; Parasympathetic: relaxes wall
- Uterus: Sympathetic: relaxation; Parasympathetic: no direct innervation
Autonomic Drugs
- Drugs that mimic or block the actions of the autonomic nervous system.
- Sympathomimetics: Mimic effects of the sympathetic nervous system (e.g., epinephrine, norepinephrine).
- Sympatholytics: Block effects of the sympathetic nervous system (e.g., beta-blockers).
- Parasympathomimetics: Mimic effects of the parasympathetic nervous system (e.g., pilocarpine).
- Parasympatholytics: Block effects of the parasympathetic nervous system (e.g., atropine).
Classification of Autonomic Drugs
- Mechanism of action: Direct-acting agonists (e.g., epinephrine), indirect-acting agonists (e.g., cocaine), mixed-action agonists (ephedrine).
- Chemical Structure: Catecholamines (e.g., epinephrine, norepinephrine) and non-catecholamines (e.g., ephedrine).
Endogenous Catecholamines (Epinephrine, Norepinephrine)
- Epinephrine: Direct effect on α1, α2, β1, β2, β3 adrenoceptors.
- Norepinephrine: Direct effect on α1, α2, β1 adrenoceptors (no β2)
Actions and Uses
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Local Actions: Decongestants, hemostasis, delayed absorption of local anesthetics, prolonged duration.
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Systemic Actions (CVS, Resp.):
- Cardiovascular system: Increased heart rate, contractility, conduction velocity, bronchodilation, blood pressure, vasodilation/constriction.
- Respiratory system: bronchodilation.
- Other targets: smooth muscle relaxation/contraction in several organs etc., uterine relaxation, allergic reactions
Adverse Effects, Contraindications, and Preparations
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Adverse Effects:
- Tachycardia, arrhythmias, hypertension, angina, cerebral hemorrhage.
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Contraindications:
- Coronary heart disease, hypertension, arrhythmias, peripheral vascular disease.
- Preparations & dosage - varies by drug
Specific Drugs
- Epinephrine (adrenaline): Uses in anaphylactic shock, local vasoconstriction, cardiac arrest.
- Norepinephrine (noradrenaline): Uses in hypotensive states after sympathectomy or spinal anesthesia.
- Midodrine: Treatment of hypotension
- Xylometazoline and oxymetazoline: Topical decongestants
- Isoprenaline: Use in heart block, bronchial asthma
- Dobutamine: Use in acute heart failure
- Salbutamol, terbutaline: Short-acting bronchodilators
- Formoterol and salmeterol: Long-acting bronchodilators
- Ritodrine: Uterine relaxant
- Amphetamine: CNS stimulant, increase wakefulness
Note: Further details on specific drugs' actions, uses, dosages, etc., need to be studied separately within each topic for thorough understanding.
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Description
Explore the autonomic nervous system with this quiz, focusing on its two branches: the sympathetic and parasympathetic systems. Understand the physiological effects, anatomical features, and functions of the sympathetic nervous system. Ideal for students of neuroscience or physiology.
