Nerve Impulse

1
Nerve Impulse

• - both an electric and chemical experience

2
Nerve Impulse

• Stimuli causes a change in both the chemical and
  electrochemical properties in a neuron
• consumes oxygen and ATP
• changes axon membrane permeability to sodium
  (Na) and potassium (K) ions

3
A Nerve impulse is run by the...

• SODIUM - POTASSIUM PUMP
• active transport
• at rest
• Na pumped out - 3
• K pumped in - 2
• ? producing opposing (relative) charges on either
  side of the axon membrane

4
Polarization

• Both sides of the axon membrane with opposing
  charges
• Resting Membrane Potential is before the impulse
  in introduced

5
Impulse

• Stimulation causes axon membrane to become
  permeable to Na
• ? at the point of stimulation polarization is
  lost
• DEPOLARIZED

6
Action Potential

• Wave of depolarization from the dendrite to the
  axon (terminal knobs)
• All or None Response - either experiences action
  potential or not
• Threshold Stimuli - amount to trigger impulse /
  the minimum

7
Refractory Period

• Time it takes for the sodium-potassium pump to
  reestablish polarization
• during the refractory period it can NOT accept
  another impulse

8
Transfer of Impulse over the Synapse

• Neurotransmitters
• carry impulse over the synapse
• at the terminal knobs of the axons SYNAPTIC
  VESICLES store neurotransmitters

9
Upon Impulse

• Makes synaptic vesicles move towards synapse
  until it releases neurotransmitter into the
  synapse

10
On the dendrite of the adjacent neuron.

• Neurotransmitter is accepted by RECEPTOR PROTEINS
  causing an action potential to be established on
  the next neuron

11
Types of Neurotransmitters

• CHOLINESTERASE
• enzyme that breaks down acetylcholine

• ACETYLCHOLINE
• transfers the impulse in the motor neurons of the
  skeletal muscles

NORADRENALINE / NORESPINEPHRINE - causes body to
go into STRESS conditions increasing heart rate
gland secretions