NEUROPHYSIOLOGY
A. Neurons
1. Structure
2. Types
a. Myelinated - has myelin sheath.
i. Speeds impulse conduction via saltatory conduction (impulse hops from node to node; therefore, more efficient).
ii. Enhances fidelity of neuron fiber regeneration.
b. Non-myelinated - has no myelin sheath
3. Synaptic Transmission
4. Neural Circuits
a. Linear
b. Diverging
c. Converging
d. Parallel
e. Reverberating
B. Reflexes
1. Anatomy - Cross section of Spinal cord at the level of a spinal nerve.
2. Requirements
a. Receptors - detect stimuli (e.g. rods in eyes)
b. Transmitters - carry impulses (neurons)
i. Afferent (sensory) - carry impulses toward central nervous system.
ii. Association - make proper connections between afferent and efferent (below) neurons.
aa. interneurons (=internuncial neurons) - connect sensory and motor on the same side of the body.
bb. commissural neurons - connect sensory and motor on opposite sides of the body.
iii. Efferent (motor) - carry impulses away from the central nervous system.
c. Effectors - respond to stimuli (e.g. muscle fibers, glands)
3. Types
a. Axon
b. Two-neuron - sensory neuron synapses directly with motor neuron
c. Multiple-Neuron - sensory neuron connects with motor neuron via association neuron
i. Homolateral - response on same side as stimulus (requires interneuron)
ii. Contralateral - response on opposite side from stimulus (requires commissural neuron). Can't get contralateral without homolateral.
4. Details of stretch reflex
C. Autonomic Nervous System
1. Central Nervous System
a. Brain
b. Spinal cord
2. Peripheral Nervous System
a. Somatic - contains both sensory and motor neurons, and motor neurons reach target organ without synaptic connections
b. Autonomic - strictly motor, and the neurons make one synaptic connection in a ganglion in route to the target organ.
i. Sympathetic - thoraco-lumbar in origin. Ganglion close to spinal cord. Postganglionic neuron secretes norepinephrine.
ii. Parasympathetic - Crano-sacral in origin (about 80 - 90% of impulses carried by vagus). Ganglion close to target organ. Postganglionic neuron secretes acetylcholine.
D. Brain
1. Cerebrum
a. Cerebral Cortex - Voluntary actions, thoughts, memory, knowledge. Has both sensory and motor areas.
b. Subcortical Nuclei - inhibitory function (e.g. prevents over reaction to stretch reflex)
2. Limbic System - emotions (pleasure, pain). Very diffuse and nebulous.
3. Thalamus - Determines modality of sensations (e.i. all action potentials are the same, yet some are interpreted as vision, pain, sound, pressure, etc.). Sends impulses to proper part of brain for interpretation.
4. Hypothalamus - Autonomic Nervous System regulator
5. Reticular System - Active during wakefulness and arousal
6. Cerebellum - coordination
7. Brain Stem - primitive functions such as equilibrium control.
