Overview
This lecture explains key drug concepts, focusing on the mechanisms of action for epinephrine and atropine within the autonomic nervous system.
Drug Naming and Classification
- Every drug has a chemical name, a generic name (e.g., acetaminophen), and a brand name (e.g., Tylenol).
- Drug class describes what the drug does (e.g., antihypertensive, antipyretic, sympathomimetic).
- Mechanism of action (MOA) is how a drug produces its effects in the body.
Autonomic Nervous System (ANS): Sympathetic vs. Parasympathetic
- Sympathetic nervous system ("fight or flight") increases pupil dilation, heart rate, blood pressure, and respiratory rate; decreases digestion.
- Parasympathetic nervous system ("rest and digest") constricts pupils, lowers heart rate and blood pressure, slows breathing, and increases digestion.
Key Drug Types and Actions
- Sympathomimetics (adrenergics) mimic the sympathetic system to activate it.
- Sympatholytics block the sympathetic system, resulting in parasympathetic effects.
- Parasympathomimetics activate the parasympathetic system.
- Parasympatholytics (e.g., atropine) block the parasympathetic system, leading to sympathetic effects.
Receptors and Effects
- Alpha 1 receptor activation causes blood vessel vasoconstriction.
- Beta 1 receptor activation increases heart rate and heart contractility.
- Beta 2 receptor activation causes lung bronchodilation.
- Agonists turn receptors on; antagonists block receptor effects.
Mechanism of Action: Epinephrine vs. Atropine
- Epinephrine is a sympathomimetic agonist acting on alpha 1, beta 1, and beta 2 receptors (vasoconstriction, increased HR, bronchodilation).
- Atropine is a parasympatholytic; it blocks vagus nerve action, reducing parasympathetic effects and indirectly increasing heart rate.
Key Terms & Definitions
- Sympathomimetic (Adrenergic) — Drug that mimics and activates the sympathetic nervous system.
- Sympatholytic — Drug that inhibits the sympathetic system, enhancing parasympathetic function.
- Parasympathomimetic (Cholinergic) — Drug that stimulates the parasympathetic nervous system.
- Parasympatholytic — Drug that blocks the parasympathetic system (e.g., atropine).
- Agonist — Drug that activates a receptor.
- Antagonist — Drug that blocks a receptor.
Action Items / Next Steps
- Review and memorize mechanisms of action for epinephrine and atropine.
- Study key terms and receptor functions for upcoming exams.