All or none character of impulse

• Minimum strength of stimulus that cause excitement is called threshold potential
• Stimulus less than threshold potential cannot excite nerve fibre so there is no response.
• If strength of stimulus is increased then there is no change in degree of response.
• So response of nerve fibre to stimulus is always maximum.
• Thus, there will be either complete response or no response at all.

   This is the all or none character of impulse.