Functional Anatomy: Peripheral Nervous System Lecture 3

Peripheral N. S. n Cranial Nerves - 12 pair n Spinal Nerves - 31 pair n Somatic Division l Sensory information l Body Movement n Autonomic division - Homeostasis l regulation ~

Cranial Nerves n Ventral surface of brain l Olfactory – frontal lobe l Optic – thalamus l All others from brainstem n Functions l Sensory & motor (head/neck) l Homeostasis (abdomen) n Optic nerves l NOT part of PNS ~

Spinal Nerves n 1 pair for each vertebral segment n 8 cervical (C1-C8) n 12 thoracic (T1-T12) n 5 lumbar (L1-L5) n 5 sacral (S1-S5) n 1 coccygeal ~

Spinal Nerves n Thoracic nerves relatively small u back & ribs n Cervical, lumbar, & sacral: large nerves u rest of the body n Dermatomes l Receptive fields of body l Overlap  redundancy ~

Somatic Nervous System n Sensory input l sensory receptors  l dorsal root ganglion (DRG)  l dorsal horns n Motor output l ventral horns  muscles ~

Somatic N. S. - Motor Spinal Cord Motor Neuron n Striate muscle l nerve-dependent l uninterrupted neuron l excitatory only n Neurotransmitter l Vagusstoff l Acetylcholine (Ach) ~ Effector +

n Homeostasis l Not nerve- dependent n Effectors l Smooth Muscle l Cardiac Muscle l Glands ~ Autonomic N. S.

n Sympathetic l Emergency, flight/fight n Parasympathetic l Conservation / vegetative ~ Autonomic Subdivisions

Effector Ganglion Preganglionic neuron Postganglionic neuron Autonomic: General Features ACh

Pharmacology of Autonomic NS n Preganglionic neuron l releases ACh l Different NT at effectors n Parasympathetic division l Acetylcholine (Ach) n Sympathetic division: l Acceleranstoff l Norepinephrine (NE) ~

Sympathetic vs. Parasympathetic n Sympathetic l ganglia near spinal cord l interconnected  active together l long-lasting effects n Parasympathetic l ganglia near effector l discrete  active independently l transient effects n Antagonistic regulation ~

Effector Responses Effector Sympathetic Parasympathetic Heart + - Respiration + - GI - + Immune system - + Sweat glands + no input Iris + (radial) + (sphincter) ~

Parasympathetic Post- Pre- Sympathetic Adrenal Glands ACh Glands Smooth muscle NE

Sympathetic Arousal Syndrome n Fight or flight situations l Diffuse sympathetic activation n Adrenal glands l releases NE into blood l maintains sympathetic arousal n Parasympathetic rebound n Stress & health ~