Sympathetic and Parasympathetic Nervous Systems PDF
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San Joaquin Valley College - Visalia
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Summary
This document provides an overview of the sympathetic and parasympathetic nervous systems. It details their functions, key neurotransmitters, and effects on various bodily processes. The document also covers related agents influencing these systems, and their clinical applications.
Full Transcript
The sympathetic and parasympathetic nervous systems are subdivisions of the autonomic nervous system (ANS), which regulates involuntary physiological functions such as heart rate, digestion, and respiratory rate. Sympathetic Nervous System (SNS) Function: The "fight-or-flight" system, activat...
The sympathetic and parasympathetic nervous systems are subdivisions of the autonomic nervous system (ANS), which regulates involuntary physiological functions such as heart rate, digestion, and respiratory rate. Sympathetic Nervous System (SNS) Function: The "fight-or-flight" system, activated during stress or emergencies. Key Neurotransmitter: Norepinephrine (primary), epinephrine (adrenaline). Effects: ○ Increases heart rate and blood pressure. ○ Dilates bronchi (improves airflow). ○ Dilates pupils. ○ Inhibits digestion and urinary activity. ○ Stimulates glucose release (for energy). Agents influencing SNS: 1. Sympathomimetics (Adrenergic Agonists): Stimulate adrenergic receptors. ○ Examples: Epinephrine, norepinephrine, albuterol. ○ Uses: Asthma, hypotension, anaphylaxis. 2. Sympatholytics (Adrenergic Antagonists): Block adrenergic receptors. ○ Examples: Beta-blockers (e.g., propranolol), alpha-blockers (e.g., prazosin). ○ Uses: Hypertension, arrhythmias, anxiety. Parasympathetic Nervous System (PNS) Function: The "rest-and-digest" system, active during relaxation. Key Neurotransmitter: Acetylcholine. Effects: ○ Decreases heart rate. ○ Constricts bronchi. ○ Stimulates digestion and gland secretion. ○ Promotes bladder contraction and urination. ○ Constricts pupils. Agents influencing PNS: 1. Parasympathomimetics (Cholinergic Agonists): Stimulate cholinergic receptors. ○ Examples: Bethanechol, pilocarpine. ○ Uses: Urinary retention, glaucoma. 2. Parasympatholytics (Anticholinergics): Block cholinergic receptors. ○ Examples: Atropine, ipratropium bromide, scopolamine. ○ Uses: Bradycardia, COPD, motion sickness. Receptor Types and Their Manipulation Adrenergic Receptors (SNS) Alpha-1: Vasoconstriction, pupil dilation (blocked by alpha-1 antagonists). Alpha-2: Inhibits norepinephrine release (stimulated by clonidine). Beta-1: Increases heart rate and contractility (blocked by beta-1 blockers like metoprolol). Beta-2: Bronchodilation and vasodilation (stimulated by beta-2 agonists like albuterol). Cholinergic Receptors (PNS) Muscarinic: Found in smooth muscles, glands (blocked by atropine). Nicotinic: Found in ganglia and skeletal muscle (blocked by neuromuscular blockers like pancuronium). Clinical Application By manipulating these systems using specific drugs, healthcare providers can manage conditions like asthma, hypertension, heart failure, bradycardia, and more. Balancing the activation or inhibition of these systems is critical for therapeutic success.
