14. Somatic nerve fibers
• These are α type motor nerve fibers.
• The neurotransmitter released at the neuron endings is
acetylcholine(Ach).
• It always leads to muscles excitation . Inhibition takes place
centrally due to participation of interneurons.
15. Autonomic nerve fibers
• They innervate smooth muscles , cardiac muscles
and Glands.
• Their main work is to maintain homeostasis with the
help of autonomic nervous system.
• They can lead to either excitation or inhibition of
Effector organs.
18. Excitability:
• nerve fibres are highly excitable tissue
• respond to various stimuli
• Capable of generating electrical impulse
Conductivity:
• action potential is generated in the nerve fibre,
which is propagated along its entire length to the
axon terminal.
19. Refractive period:
• during action potential the excitability of a nerve
become reduced
• that is a new impulse cannot be generated during a
Action Potential
• Types:
a. Absolute refractory period (ARP)
b. Relative refractory period( RRP)
20. Unfatiguability :
• Nerve fibres can not be fatigued even when they are
stimulated continuously.
All or none response:
• Either all of the action potential is seen or none at all
• If a stimulus of threshold strength is applied action
Potential will be generated
• Further increase in strength of stimulus or duration
has no effect on amplitude of action Potential
• But can affect frequency
21. Summation:
• Application of a sub threshold stimulus does not
evoke an action potential. However if sub threshold
stimuli are applied in rapid succession they are
added and they produce an action potential.
Accommodation:
• Application of continuous stimuli may decrease the
excitability of nerve fibre.
