1. The Peripheral Nervous System
Chapter 13-14

2. Nervous System Structural Overview

3. Peripheral Nervous System
All neural structures outside of the brain and spinal cord.
Includes sensory receptors, peripheral nerves, ganglia, and efferent motor endings.

4. Sensory Receptors
Respond to specific changes in their environment called stimuli
General Sensory Receptors:
Free nerve endings
Tactile (Merkel) discs
Hair follicle receptors
Tactile (meissner’s) Corpuscles
Lamellar (pacinian) corpuscles
Ruffini Endings
Muscle Spindles
Tendon organs

5. Somatosensory Neural Integration
Three main levels of neural integration in the sensory system
Receptor Level
Circuit Level
Perceptual Level

6. Processing at the Receptor Level
Step 1: Stimulus excites receptor and action potentials reach the CNS
Stimulus must match the specificity of the receptor
stimulus must be applied within the receptor field
stimulus must be converted into a graded potential (transduction)
Adaptation

7. Processing at the Circuit Level
Step 2: Impulses must be delivered to the appropriate region of the cortex for localization and perception of the stimulus.

8. Processing at the Perceptual Level
Step 3: Sensory input is interpreted in the cerebral cortex

9. Perception of Pain Activated by extremes of pressure or temperature
Sharp, then aching/burning. A delta, c fibers
Based on situation
Pain threshold versus pain tolerance

10. Nerves Cord-like organs composed of bundles of axons.
Connective tissue wrappings:
endoneurium, perineurium (fascicles), epineurium.
Nerves classified by transmission direction:
Sensory nerves, motor nerve, mixed nerves.

11. Peripheral Motor Endings
The Neuromuscular Junction

12. Motor Integration Levels of Motor Control:
The Segmental Level (reflexes, CPG’s)
The Projection Level (initiate voluntary movement, oversee the segmental level).
The Precommand Level (Cerebellum, basal nuclei: coordination, timing, start/stop)

13. Reflex Activity
The Reflex Arc
inborn or learned

14. Components of a Reflex Arc
Receptor
Sensory Neuron
Integration Center
Motor Neuron
Effector
Can be either somatic or autonomic

15. Spinal Reflexes
Stretch Reflex

16. Spinal Reflexes
The Tendon Reflex

17. Spinal Reflexes
The Flexor and Crossed Extensor Reflexes

18. Superficial Reflexes

19. The Autonomic Nervous System

20. ANS Divisions and Roles
Parasympathetic Division
Rest and Digest Division
Keeps body energy as low as possible
Sympathetic Nervous System
Fight or Flight System
Prepares body for emergency situations

21. Comparison of Somatic NS and ANS

22. ANS Anatomy Dual Innervation Sites of Origin
Relative lengths of their fibers
Location of their ganglia

23. ANS Anatomy Parasympathetic (craniosacral) Division Cranial part
Occulomotor N.
Facial N.
Glossopharyngeal N.
Vagus N. (Multiple Plexi)
Sacral Part
Pelvic Splanchic n.
Inferior hypogastric plexus

24. ANS Anatomy Sympathetic (Thoracolumbar division)
Preganglionic fibers arise from Lateral Horns of segments T1-L2

25. ANS Anatomy
Sympathetic trunks and pathways

26. 3 Pathways of Synaptic Innervation
Synapse at the Same Level

27. 3 Pathways of Synaptic Innervation
Synapse at a higher or lower level

28. 3 Pathways of Synaptic Innervation
Synapse in a distant collateral ganglion anterior to the vertebral column

29. ANS Physiology Neurotransmitters and Receptors Acetylcholine
Released by all ANS Preganglionic axons and all parasympathetic postganglionic axons (cholinergic fibers)
Norepinephrine
Most sympathetic postganglionic axons (adrenergic fibers)

30. Cholinergic Receptors
Nicotinic Receptors
Found on sarcolemma of skeletal fibers, all postganglionic neurons, adrenal medulla
Muscarinic Receptors
Parasympathetic target organs

31. Adrenergic Receptors alpha and beta receptors
alpha 1, 2, Beta 1, 2, 3.
can be either excitatory or inhibitory

32. Pharmacological Effects
Atropine (anticholinergic)
Neostigmine (anticholinesterase)
B2 activators (dilate airways)
Beta Blockers (slow heart rate, lower BP)

33. Interactions of the Autonomic Divisions
Dual Innervation
Antagonistic Interactions
Sympathetic and Parasympathetic Tone
Unique roles of the Sympathetic Division
thermoregulatory response to heat, renin release, metabolic effects
Localized Versus diffuse effects

34. Control of Autonomic Function
Brain Stem and Spinal Cord controls
Hypothalamic Controls
Cortical Controls