6.5 Transmission of Nerve impulses Flashcards
Central Nervous System (CNS)
Brain
Spinal Chord
Peripheral Nervous System
Nerves in head
Cranial nerves
Spinal Nerves
Label Neuoron
Dendrites
Nucleus
Cell body
Axon
Myelin Sheath
Nodes of Ranvier
Synaptic terminals
Action Potential
Wave of Sodiam & Potassium ions moving in and out of the neuron.
Creates electrical impulses
Resting Potential
Sodium Potassium pumps continue to work –> SOPI
3 Sodium OUT
2 Potassium IN
ATP reqired since it is ACTIVE transport
Whole Process of an Action Potential
- Starts off -70mV inside the neuron.
- Na-K pump slowly takes electronegativity from -70mV to -40mV
- Action Potential now starts at -40mV
- Sodium voltage gated channels now open
- Na+ floods in creating electronegativity of -40mV to +40mV going all the way down the membrane
- At +40mV theSodium voltage gated channels close
- Potassium voltage gated channels now open
- K+ ions flow out the cell –> +40mV to -75mV
- Potassium voltage gated channels close
- Refractory period takes place
- Reaches resting potential again
Refractory period
Occurs after an action potential
Sodium channels aren’t ready to open again
Prevents signal from going back to the brain due to Na voltage gated channels not being able to depolarize the axon again
Depolarization & Repolarization
Depolarization: -70mV to +40mV
Repolarization: +40mV to -75mV
‘Overshoot’ at -75mV
Oscilliscopes
Conduction Velocity
Speed the impulse travels
- Diameter of fiber
- Presence or abseence of myelin
- Neurons with myelin (action potential ‘hops’ along the myelin sheath)
Synaptic transmission
How neurons interact with eachother
The Synapse
Presynaptic neuron terminal:
Action potential causes Voltage Gated Calcium Ion Channels to open allowing calcium ions to diffuse in the cell.
Calcium ion cause vesicles to realease acetylcholine into synaptic cleft.
Acetylcholine binds to ion channels on post synaptic neuron, allowing them to open.
Sodium ions then flood into post synaptic neuron.
Causes new action potential in post synaptic neuron due to polarization of -70mV to -40mV.
Acetylcholinesterase (AChE) breaks acetylcholine in synapse into Acetate & Choline
Acetate goes away, Choline is reused in the cyle.
Neonicotines
Insecticides produced by nicotine plants.
Bonds to acetylcholine receptors in insects forming paralisis killing them.
Blocks post synaptic neuron from having an action potential
Nicotine
Increases release of dopamine when an action potential occurs in presynaptic terminal.
cocaine
Blocks reuptake of dopamine once it is released
