1. Nervous system 2
Nerve resting potential and impulse action potentials
Nerve fibers types and speed of conduction

3. Resting potential
Potential for a nerve impulse due to polarized state
Relatively negative within nerve
-70 mV inside nerve cells due to 3 Na+ ions transported
out of cell for every 2 K+ ions transported in to cell

7. Nerve impulse

11. Nerve impulse frequency
Limited by rate of Na+ // K+ repolarization
Refractory period – neuron cannot generate a new
impulse
Absolute refractory, 2nd impulse cannot be initiated
Relative refractory, 2nd impulse can be initiated with
abnormally strong stimulus

12. Speed of nerve impulse conduction
Affected by:
Temperature
Heat increases speed of conduction
Cold decreases (or stop) speed of conduction
Diameter of fiber;
The larger the fiber, the faster the speed of impulse
Myelination
Myelinated nerves much faster speed of conduction

15. Nerve fiber types
Type A
Large diameter, myelinated, short refractory and fast
conduction (130 m/sec).
Motor (efferent) neurons, touch pressure, temp and
proprioception (afferent) receptors

16. Nerve fiber types
Type B
Medium diameter, myelinated, conduction speed
not as fast as Type A
Smooth muscle and glandular (efferent) innervation
and skin and visceral (afferent) receptor

17. Nerve fiber types
Type C
Small diameter, not myelinated.
Longer refractory period
Slower speed of conduction
Sensory (afferent) from skin and ANS efferent to
cardiac and smooth muscle

19. Continuous
conduction
(slower)
Saltatory
conduction
(faster)