Podcast
Questions and Answers
What condition is adrenaline primarily used to treat in severe allergic reactions?
What condition is adrenaline primarily used to treat in severe allergic reactions?
What physiological effect does adrenaline have on the smooth muscles in the airways?
What physiological effect does adrenaline have on the smooth muscles in the airways?
Which of the following conditions contraindicates the use of adrenaline?
Which of the following conditions contraindicates the use of adrenaline?
What is one effect of adrenaline on the cardiovascular system?
What is one effect of adrenaline on the cardiovascular system?
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What type of beta-blocker blocks both beta 1 and beta 2 receptors?
What type of beta-blocker blocks both beta 1 and beta 2 receptors?
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What type of adrenergic receptor is responsible for bronchodilation?
What type of adrenergic receptor is responsible for bronchodilation?
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In which condition are beta-blockers NOT typically used as a treatment?
In which condition are beta-blockers NOT typically used as a treatment?
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Which receptor is associated with the hydrolysis of PIP2?
Which receptor is associated with the hydrolysis of PIP2?
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What primary effect occurs when adrenaline stimulates alpha 1 receptors in blood vessels?
What primary effect occurs when adrenaline stimulates alpha 1 receptors in blood vessels?
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Which of the following is a common side effect of beta blockers?
Which of the following is a common side effect of beta blockers?
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How do beta-blockers primarily affect heart function in patients with heart failure?
How do beta-blockers primarily affect heart function in patients with heart failure?
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Why should adrenaline be avoided in patients with heart disease?
Why should adrenaline be avoided in patients with heart disease?
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Which condition should beta blockers be avoided in?
Which condition should beta blockers be avoided in?
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Which adrenergic receptor type is coupled to the Gs protein?
Which adrenergic receptor type is coupled to the Gs protein?
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How does adrenaline affect the gastrointestinal tract?
How does adrenaline affect the gastrointestinal tract?
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What is one major action of adrenaline in the body?
What is one major action of adrenaline in the body?
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Which of the following is TRUE about beta blockers?
Which of the following is TRUE about beta blockers?
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What is a contraindication for using beta blockers?
What is a contraindication for using beta blockers?
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What is the result of adrenaline binding to beta 1 receptors?
What is the result of adrenaline binding to beta 1 receptors?
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What occurs as a result of adrenaline affecting the urinary bladder?
What occurs as a result of adrenaline affecting the urinary bladder?
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What effect do beta blockers have on the heart rate?
What effect do beta blockers have on the heart rate?
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Which drug class mimics the effects of the sympathetic nervous system?
Which drug class mimics the effects of the sympathetic nervous system?
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Which condition is NOT treated by beta blockers?
Which condition is NOT treated by beta blockers?
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What is the primary function of the sympathetic nervous system?
What is the primary function of the sympathetic nervous system?
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Which of the following is a side effect of beta blockers?
Which of the following is a side effect of beta blockers?
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Which of the following is NOT a function of the sympathetic nervous system?
Which of the following is NOT a function of the sympathetic nervous system?
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What type of drug mimics the effects of the sympathetic nervous system?
What type of drug mimics the effects of the sympathetic nervous system?
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Which response is primarily controlled by the parasympathetic nervous system?
Which response is primarily controlled by the parasympathetic nervous system?
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How does adrenaline function in the body during stress?
How does adrenaline function in the body during stress?
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In comparison to the sympathetic nervous system, what is a key characteristic of the parasympathetic nervous system?
In comparison to the sympathetic nervous system, what is a key characteristic of the parasympathetic nervous system?
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What role do adrenergic receptors play in the sympathetic nervous system?
What role do adrenergic receptors play in the sympathetic nervous system?
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During a 'fight or flight' situation, which physiological change is most likely to occur?
During a 'fight or flight' situation, which physiological change is most likely to occur?
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Study Notes
Adrenaline
- Adrenaline is a sympathomimetic catecholamine
- It is present in the adrenal medulla (80% of secretions) and some CNS tracts
- Not absorbed orally
Adrenaline Kinetics
- Routes of administration: subcutaneous (1/2 mL of 1/1000 solution), inhalation (1/100 solution by nebulizer or atomizer), eye drops (2% solution), intra-cardiac (in cardiac resuscitation)
- Subcutaneous administration causes vasoconstriction, which slows absorption
- Inhalation is used in bronchial asthma
- Eye drops are used in open-angle glaucoma
- Intra-cardiac use is for impaired circulation during cardiac resuscitation
Adrenaline Fate
- Distribution: does not pass the blood-brain barrier
- Reuptake: by nerve endings and tissues (80%)
- Metabolism: by MAO (Monoamine oxidase) and COMT (Catechol-O-methyltransferase) (18%)
- Excretion: unchanged in urine (2%)
Adrenaline Actions
- Systemic actions:
- Heart: increases heart rate and force of contraction
- Blood vessels: constriction of skin, mucous membranes, and renal blood vessels, dilation of skeletal and coronary blood vessels.
- Blood pressure: increase in systolic blood pressure (SBP) due to increased cardiac output (COP) and increased venous return, decrease in diastolic blood pressure (DBP) due to vasodilation of skeletal vessels and reduced peripheral resistance.
- Respiratory: decongestion of bronchial mucosa, bronchodilation
- Gastrointestinal Tract: constriction of sphincters and relaxation of intestinal wall.
- Urinary Bladder: constriction of bladder sphincter, relaxation of bladder wall causing urine retention.
- Uterus: contraction in early pregnancy, relaxation in late pregnancy
- Skeletal Muscles: vasodilation, facilitation of neuromuscular transmission, anti-fatigue
- Metabolic: hyperglycemia
- Other: anxiety; physiological antagonist of histamine
- Local actions
- Skin: localized vasoconstriction via alpha-1 receptors
- Mucous membranes: (e.g., nasal): vasoconstriction via alpha-1 receptors - decongestion and homeostasis
Adrenaline Local Uses
- Open-angle glaucoma
- Haemostatic nasal pack in epistaxis (not in hypertension patients)
- With local anaesthetics (except cocaine): slows absorption, increases duration, reduces systemic toxicity and bleeding
Adrenaline Systemic Uses
- Anaphylactic shock and urticaria
- Acute bronchial asthma
- Acute insulin hypoglycemia
- Cardiac resuscitation
- Contracting ring of uterus during labor
Adrenaline Contraindications
- Around-the-finger and toe gangrene
- Hypertension
- Hemorrhagic shock
- Thyrotoxicosis
- Pulmonary embolism
- Digitalis administration, general anaesthesia causing cardiac arrhythmias
- Non selective beta blocker
Beta-Adrenergic Blockers
- Mechanism: competitive blocking of beta-adrenergic receptors
- Intrinsic Sympathetic Activity (ISA): partial agonist activity
- Classification:
- Non-selective: blocks β1 and β2 receptors, e.g., propranolol, sotalol, timolol, pindolol; Additional a-blocking effect (e.g., labetalol and carvedilol)
- Selective: blocks primarily β1 receptors, e.g., metoprolol, atenolol, bisoprolol, esmolol
Beta-Blockers Kinetics
- Absorption: orally and parenterally
- Distribution: throughout the body; highly lipophilic drugs like propranolol and timolol cross the BBB.
- Propranolol: extensive hepatic metabolism; short duration of action, given t.d.s (three times a day)
- Esmolol: rapid metabolism by RBC esterase; given by IV infusion; suitable for patients with renal or hepatic diseases
Beta-Blockers Pharmacodynamics
- Heart: decreases heart rate and force of contraction (by beta1)
- Blood vessels: vasodilation of skeletal muscles and coronary blood vessels (by beta2), vasoconstriction of skin, mucous membranes, and renal blood vessels (by alpha1)
- Anti-hypertensive: by decreasing sympathetic outflow and reducing renin secretion
- IOP: reduced formation of aqueous humor
- Bronchi: bronchospasm (by beta2 blockade)
- Metabolism: hypoglycemic effect, masks symptoms of hypoglycemia
Beta-Blockers Uses
- Heart: arrhythmias, angina, myocardial infarction (MI), hypertension, heart failure
- Other: pheochromocytoma, portal hypertension, thyrotoxicosis, glaucoma, migraine headache, anxiety
Beta-Blockers Side Effects
- Heart: bradycardia, heart block, angina pain
- Other: cold extremities, intermittent claudication, acute bronchial asthma
Beta-Blockers Contraindications
- Heart: bradycardia (< 60 bpm), heart block, advanced stages of heart failure, vasospastic angina.
- Other: bronchial asthma, diabetic patients, pregnancy
MCQs
- Adrenaline addition to local anaesthetics: delays absorption, prolongs duration, and reduces toxicity
- Physiological antagonist of adrenaline: acetylcholine
- Beta-blockers use: hypertension, heart block, angina
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Description
This quiz covers the key concepts related to the use of adrenaline and beta-blockers in medical treatments. It explores their physiological effects, contraindications, and the specific receptors involved in their actions. Test your knowledge on these crucial pharmacological agents.
