The types of antagonism are:

Correct Answer: D

Rationale: Step-by-step rationale: 1. Competitive antagonism occurs when two substances compete for the same receptor. 2. In this type, the antagonist binds to the receptor site, preventing the agonist from binding. 3. This results in a decrease in the response produced by the agonist. 4. Summarized, potentiated, and additive antagonisms do not involve direct competition for the receptor site. 5. Summarized means concise or brief, potentiated means increased effect, and additive means combined effect. 6. Therefore, the correct answer is D (Competitive) as it specifically describes the type of antagonism where substances compete for the same receptor site.

Correct Answer: D

Rationale: The correct answer is D: Ventricle. Muscarinic receptors are predominantly found in the atria, sinoatrial node, and atrioventricular node. Blocking these receptors can lead to decreased heart rate and conduction. The ventricles, however, are more sensitive to beta-adrenergic stimulation rather than muscarinic blockade. This is because beta-adrenergic receptors play a significant role in the contractility of the ventricles. Therefore, the ventricles are not as sensitive to muscarinic receptor blockade compared to the other parts of the heart.

Correct Answer: C

Rationale: The correct answer is C: Interaction with adrenoreceptors. Indirect action involves affecting catecholamines' release, reuptake, or displacement, not direct interaction with adrenoreceptors. A: Displacement of stored catecholamines is correct as it refers to causing the release of stored catecholamines. B: Inhibition of reuptake is correct as it refers to preventing the reuptake of catecholamines. D: Inhibition of release of endogenous catecholamines is correct as it refers to stopping the release of catecholamines from nerve endings.

Correct Answer: A

Rationale: The correct answer is A: Formoterol. It is a long-acting beta2-adrenergic agonist used in bronchial asthma therapy to dilate airways by relaxing smooth muscles. Norepinephrine (B) is a vasopressor, not used in asthma. Methoxamine (C) is an alpha1-adrenergic agonist, not indicated for asthma. Dobutamine (D) is a beta1-adrenergic agonist mainly used in heart failure, not asthma. Formoterol's mechanism of action aligns with the therapeutic goal of bronchial asthma treatment, making it the correct choice.

Correct Answer: C

Rationale: The correct answer is C: Pheochromocytoma. Beta-receptor blocking drugs are contraindicated in pheochromocytoma because they can potentially worsen hypertension due to unopposed alpha-adrenergic effects. Choice A is correct as beta-blockers are commonly used in hypertension, ischemic heart disease, and cardiac arrhythmias. Choice B is incorrect as beta-blockers are used in the treatment of glaucoma to reduce intraocular pressure. Choice D is incorrect as beta-blockers are used to manage symptoms of hyperthyroidism such as tachycardia and tremors.