Speed of nerve impulse
- Created by: fahmida1998
- Created on: 05-10-16 19:13
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- Speed of nerve impulse
- Refractory period
- Period after AP generation anywhere in axon, inward movement of Na+ ions prevented d.t closure of Na+ voltage-gated channel.
- AP can't be generated
- Limits strength of stimulus detected
- 3 Purposes
- 1. ENSURES AP- 1D ONLY
- AP - Can only pass from active region to resting region as they can only move in forward direction
- Prevents AP spreading both directions
- AP - Can only pass from active region to resting region as they can only move in forward direction
- 2. PRODUCES DISCRETE IMPULSES
- Refractory period ensures APs are seperated
- 3. LIMITS NO. OF APs
- APs are separate -> limits AP frequency -> limits strength of stimulus detected
- 1. ENSURES AP- 1D ONLY
- Period after AP generation anywhere in axon, inward movement of Na+ ions prevented d.t closure of Na+ voltage-gated channel.
- Factors effecting speed action potential travels
- 2* Myelin sheath- acts as an electrical insulator, prevents action potential forming on axon covered in myelin
- 1* Greater axon diameter -> faster conductance
- 3* Temp- (effects diffusion rate of ions)- higher-> faster nerve impulse
- Energy for active transport -> from resp -> controlled by enzymes-> efficient at high temps but can denature -> impulses fail to be conducted
- nerve impulse- transmission of an action potential along axon
- once action potential set up, moves from 1 end of axon to other (action potential at end same as at start)
- NERVE IMPULSES
- All or nothing principal
- Certain level of stimulus- THRESHOLD VALUE = Action potential
- below TV, no AP -> no impulse generated
- Any stimulus of whatever strength, below TV-> fail to make AP
- Any stimulus above TV -> generate action potential -> nerve impulse will travel
- Action potentials
- Are all about same size, so strength of stimulus can't be detected by size of action potentials
- How organisms perceive size of stimulus
- 1. Impulse frequency: + -> larger stimulus
- 2. Having diff neurons with diff TV
- How organisms perceive size of stimulus
- Are all about same size, so strength of stimulus can't be detected by size of action potentials
- Filter: prevents setting up nerve impulses for minor stimuli -> not overloaded
- Certain level of stimulus- THRESHOLD VALUE = Action potential
- All or nothing principal
- Refractory period
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