PSYCH 15 Lecture Notes - Lecture 4: Myelin, Sodium Channel, Axon Terminal
Chapter 4: Neural Conduction and Synaptic Transmission
- No physical contact between the axon terminal and the dendrites: this hole is called the synapse
- Little balls inside are neurotransmitters
- Vesicles are envelopes that contain all the neurotransmitters
Release of Neurotransmitter Molecules
- When vesicles go to the terminal of the axon terminal, the brain of the vesicle will fuse with the
terminal membrane and dump all the neurotransmitters
o Exocytosis: the process of emptying the NT
- What causes a neuron to pop to the next neuron = action potential
- Whenever a cell is undergoing action potential, calcium channels open
- Calcium is needed for exocytosis to happen
o If ot eough the ells a’t fuse
Resting Membrane Potential
- When a cell is resting, just chilling
- When at rest, the inside is more negative than the outside of the cell
- About -70mV
- As long as there is a difference, the cell is polarize aka carries a charge
- If the cells charge strays away from the -70mV, it means that the cell is going to do something
- Ions contributing to resting potential: sodium, chloride, potassium,
o Negatively charged proteins as well
- The neuron at rest
o A lot more sodium is outside the cell and a lot more potassium is in the cell
o Ion channels only let specific ions through when they are open
o To keep resting potential, sodium has to stay outside while potassium has to stay inside
o Potassium channels tend to be leaky
o Concentration gradient is stronger
o Small net flow of potassium going out of the cell
ccl
Ion channels
- Sodium channels are closed at rest
o Iitiate the hagig of the oltage i the ell to ake the ells, talk to eah other
o How to get them to open? There are 2 types of sodium channels
▪ Ligand-gated cells – like lock and key
o When sodium channels are open, sodium will go in bc + charged and inside is – charged
▪ Voltage-gated cells – do’t hae a lok, so o ke a ope it
• Only way to open it is if the voltage of the cell reaches a certain criteria
(threshold)
- Epsp’s: sharig a f post eaple
o No communication going on, won’t ko that ou sa the post
Chloride
- When a chloride ions open, chloride will flow into the cell
- Chloride is negatively charged, making the cell negatively charged
- Opposite of the
- Inhibitory post synaptic potential: opposite humps of the EPSP graphs
Summate:
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Document Summary
No physical contact between the axon terminal and the dendrites: this hole is called the synapse. Vesicles are envelopes that contain all the neurotransmitters. When vesicles go to the terminal of the axon terminal, the brain of the vesicle will fuse with the terminal membrane and dump all the neurotransmitters: exocytosis: the process of emptying the nt. What causes a neuron to pop to the next neuron = action potential. Whenever a cell is undergoing action potential, calcium channels open. Calcium is needed for exocytosis to happen. When a cell is resting, just chilling. When at rest, the inside is more negative than the outside of the cell. As long as there is a difference, the cell is polarize aka carries a charge. If the cells charge strays away from the -70mv, it means that the cell is going to do something. Ions contributing to resting potential: sodium, chloride, potassium: negatively charged proteins as well.
