Peripheral Nervous System Autonomic Branches: Sympathetic Parasympathetic

The Autonomic Nervous System Darn Important to Homeostasis! Paired Neurons: Preganglionic Neurons: From Brain Stem or Spinal Cord to: Postganglionic Neurons: To effector organ Exception: Only 2 nerves directly innervate their effector organ…

The Exceptions are… The sympathetic innervation of the adrenal medulla gland The parasympathetic innervation of the smooth muscle in the airways

Sympathetic vs. Parasympathetic “Accelerator” Origin: T1-L2 Postganglion Location: Near “Fight or Flight” response to perceived stress “Brakes” Origin: Brainstem and S2-S4 Postganglion Location: Effector Organ “No Worries”…

Set Up: Sympathetic NS u Nerves come from spinal cord to Ganglia, then another neuron extends on to organ u Referred to as Preganglionic & postganglionic Organ Ganglia Pre Post

Set Up: Parasympathetic NS Nerves come from brainstem or S2-24 – Synapse with postganglionic neurons in or near effector organs Pre- Post- Effector Organs

All Organs are Innervated By BOTH the Sympathetic And Parasympathetic Nervous Systems: IN GENERAL: Their actions are reciprocal. The PSNS calms us down.

Cardiac Nerve Innervation Parasym Symp.

Sympathetic vs. Parasympathetic Neurotransmitters Emergency Rescue “Get your adrenaline (Norepinepherine) going” Long Term Maintenance “Cool your jets” (Acetylcholine) ** Same as skeletal muscles but different receptors

Central Control of ANS: The Hypothalamus controls the Autonomic Nervous System with the help the brainstem etc… Consider the scenario: Being called on to explain to the class the physiology of an action potential…while you are daydreaming about the weekend…RUN! (you might be thinking)

The Physiological Response is Predictable: Increase HR/BP Decreased digestive functions Increased Glucose mobilization Palms sweat

The Classic “Fight or Flight” Syndrome Orchestrated by the Sympathetic Nervous System

Coloring Guide to the ANS: Sympathetic: Preganglionic Nerve Fibers: Releasing Ach: Color Blue (A) Postganglionic Nerve Fibers: Releasing Norepinepherine: Color Red (B, C, D, E)

Coloring the ANS: Parasympathetic: Preganglionic Fibers: Release Ach: Color Blue (A1-4, D:S2-4) Postganglionic Fibers: Also Release Ach: Color Purple (B1-4, E)

Drugs and the ANS Mimic the SNS: Isoproterenol (asthma), Ephedrine (diet) In General: Bronchodilation, pupil dilation, Increased HR Toxicity: Severe hypertension, muscle tremors,arrhythmias, MI

Drugs and the ANS: Mimic PSNS: Propranolol (hypertension, migraines) – Actually BLOCKS the SNS activity, so mimics PSNS In General: reduced HR/BP Toxicity: Bronchoconstriction, heart block, CNS depression

Continue Reviewing: Finish Content Review: (30, ) Start to test your ability to apply your knowledge by doing the predict questions throughout the chapter.