PSYB65 – Lecture 4
Neuron – Dendrites => Cell body =>Axon => Terminal Buttons
Ion channels in membrane of neurons:
− When stimulated, they open and allow sodium into the cell (sodium is positively charged)
− The inside of the cell becomes more positive, and if enough sodium goes in, the cell reaches a
threshold. ==>All the pores open up, makes the cell extremely positive.
This spike is known as an action potential.
=> Starts in the cell body, zips down to axon.
=> Goes down to the synapse (gap between terminal buttons and the next cell's dendrite)
• Synaptic vesicles carry transmitter substances.
• When the action potential reaches the end of the axon, vesicles open up and stimulate the
Synaptic cleft = synapse
Receptors on the axon side are known as pre-synaptic.
Receptors on the dendrite side are known as post-synaptic.
Parkinson's Disease Schizophrenia
* Not enough dopamine * Too sensitive to dopamine
* Underactivation of dopaminergic system * Overactivation of dopaminergic system
How to intervene:
1) Dopamine has to be synthesized.
2) Transmitters have to be stored (packaged – or will be destroyed)
* Some chemicals keep them from being packaged.
4) Receptor activation
*Increase or decrease activation.
=> Certain things work for certain transmitters. Need to try all of the steps to see what works best for
the particular situation.
Getting rid of the transmitter => 2 ways
2) Degradation (destroy it) To Increase Dopaminergic To Decrease Dopaminergic
Synthesis - Increase - Decrease
Packaging --- - Decrease
Release - Increase - Decrease
ReceptorActivation - Increase - Decrease
Inactivation - Decrease - Increase
Mimicker - Looks almost identical to a transmitter substance. It can fit into the receptor and activates
Blocker - Does not activate the receptor, but fills the spot so that nothing else can. Decreases receptor
I. Monoamines (BiogenicAmines)
1) Dopamine (DA)
2) Norepinephrine (NE)
* Synthesis: Dopa => DA=> NE
B. Serotonin (5-HT)
• Synthesis: 5OHT (5-hydroxytriptoline) => 5HT (5-hydroxytriptomine)
II. Acetylcholine (ACh) => Activates muscles
• Synthesis: Choline =>AcetylCoA=>Ach
Acetylcholine Esterase breaks downAch.
Group I ==> Inactivation: Reuptake
Group II ==> Inactivation: Degradation (breakdown)
Parkinson's patients: Take L-dopa every day.
Schizophrenia patients: Dopamine receptor blockers.