Autonomic Nervous System Overview

Parasympathetic Nervous System Actions

• Constricts pupils
• Stimulates saliva secretion
• Slows heartbeat
• Constricted bronchi
• Stimulates digestion
• Stimulates liver to release bile and insulin
• Stimulates intestinal peristalsis and secretion
• Contracts bladder

Sympathetic Nervous System Actions

• Dilates pupils
• Inhibits saliva secretion
• Accelerates heartbeat
• Relaxes bronchi
• Inhibits digestion
• Stimulates liver to release glucose
• Inhibits intestinal peristalsis and secretion
• Relaxes bladder

Autonomic Nervous System Actions

• Regulates involuntary bodily functions (heart rate, blood pressure, respiration, digestion, gland secretion)
• Operates subconsciously, maintaining homeostasis and responding to internal and external changes
• Divided into sympathetic and parasympathetic divisions

Adrenergic Receptors

• Alpha 1 receptors: located in smooth muscle, blood vessels, radial muscles (eyes, etc), urinary bladder. Increases force of heart contraction, vasoconstriction, mydriasis, decreased salivary secretions, urinary sphincter contraction.
• Alpha 2 receptors: located presynaptically on adrenergic nerve terminals. Inhibits NE release, dilates blood vessels, lowers blood pressure, decreases gastrointestinal motility.
• Beta 1 receptors: located primarily in the heart & kidneys. Increases heart rate, force of contraction, increase renin release.
• Beta 2 receptors: located in smooth muscles of lungs, blood vessels supplying skeletal muscle, liver. Produces bronchodilation, relaxation (uterus, gastrointestinal tract), vasodilation.
• Beta 3 receptors: primarily in adipose tissue. Initiates lipolysis (fat breakdown)

Neurotransmitters

• Acetylcholine (ACh): primary neurotransmitter for parasympathetic system
• Norepinephrine (NE): primary neurotransmitter for sympathetic system
• Epinephrine: released from the adrenal medulla, part of the sympathetic system

Drugs Affecting the Nervous System

• Stimulants (Psychostimulants): increase dopamine and norepinephrine release.
• Effects: heightened alertness, increased energy, improved concentration, increased focus.
• Examples: Amphetamines, caffeine, cocaine
• Depressants: reduce CNS activity, leading to calming and sedative effects.
• MOA: enhance GABA activity, the primary inhibitory neurotransmitter.
• Effects: Muscle relaxation, anxiety reduction, sleep induction.
• Examples: Benzodiazepines, barbiturates, alcohol
• Opioids: act primarily on opioid receptors to produce pain relief.
• MOA: Inhibit pain pathways and increase dopamine release.
• Effects: Analgesia (pain relief), sedation, euphoria
• Examples: Morphine, codeine, fentanyl, oxycodone
• Hallucinogens (Psychedelics): alter perception, mood, and cognitive processes.
• Effects: Distorted reality perception, hallucinations, altered thought processes.
• Examples: LSD, psilocybin, MDMA
• Antidepressants: affect neurotransmitters (serotonin/ norepinephrine) to improve mood.
• MOA: Block serotonin reuptake, increasing serotonin availability.
• Examples: SSRIs (e.g., fluoxetine), SNRIs (e.g., venlafaxine), tricyclic antidepressants, MAOIs
• Antipsychotics: block dopamine receptors to reduce psychotic symptoms.
• Effects: Reduction in psychotic symptoms (hallucinations, delusions).
• Examples: Haloperidol, risperidone, olanzapine

Explore the functions of the autonomic nervous system, including the actions of the parasympathetic and sympathetic nervous systems. This quiz covers various physiological effects, receptor types, and their role in maintaining homeostasis. Test your understanding of how these systems operate to regulate involuntary bodily functions.