Exam 2: Introduction to ANS

Parasympathetic

Rest & Digest

Sympathetic

Fight or Flight

Somatic Motor Nervous System Path

Descending Fibers Synapse in Spinal Cord Sends Signal Through Cholinergic Nerve Fiber to Innervate Skeletal Muscle at NMJ (Axon Meets Muscle)

Somatic Motor Nervous System Skeletal Muscle Innervation

ACh Binds to Nicotinic Nm Receptors at the NMJ - Sodium Ions Enter the Skeletal Muscle Cell to Depolarize the Cell

Overview of Somatic Nervous System

Organization: CNS - Somatic Motor Neuron - Skeletal Muscle (One Neuron From the CNS to Skeletal Muscle)

Neurotransmitter: ACh

Receptor: Nicotinic Nm Receptor (Ligand-Gated Ion Channel)

Response: Binding of ACh to Nm Receptors - Influx of Na+ Ions - Initiation of Muscle Contraction

Skeletal Muscle is _________________, which means

neurogenic; requires somatic motor nerve input for contraction (denervation causes flaccid paralysis)

Organization of Autonomic Motor Paths

Hypothalamus - Pituitary Gland

2 Neuron Connections Between CNS and the Target/Effector Tissue

Preganglionic Neuron is Myelinated

Postganglionic Neuron is Myelinated

Parasympathetic Pathway

Craniosacral Outflow - Pre-ganglia Cholinergic Fibers Will Synapse Outside CNS (Long) - Post-ganglia (Short) Synapse to Effector Tissue

Pre-ganglia to Post-ganglia: ACh binds to Nicotinic Nn Receptors

Post-ganglia to Effector Tissue: ACh binds to Muscarinic Receptors (M2 or M3)

Parasympathetic Overview

Organization: CNS - Ganglion - Target Organ

Preganglionic neurons arise from the brainstem (cranial) and sacral spinal cord - craniosacral outflow

Long myelinated preganglionic fibers, short unmyelinated postganglionic fibers

Ganglia located near or within the target organ

ACh - Nn at ganglion; ACh - Muscarinic receptors at target organ