Science Section 2 Flashcards
What is the postsynaptic density?
Area of the membrane that consists of clusters of neurotransmitter receptors and other molecular “machinery”
What are ionotropic receptors?
These ion channels have a central pore that allows ions to pass through when ligand is bound and are found across a membrane between a postsynaptic cell
What is synaptic integration?
The EPSPs and IPSPs coming in from all synapses across the cell are added (summed) together because one EPSP or IPSP cannot trigger a postsynaptic cell to fire an actionl or hyperpolarize the cell.
What is temporal summation?
This is when multiple EPSPs or IPSPs occur in rapid succession at the same synapse and are summed up over time
What is spatial summation?
When multiple EPSPs or IPSPs occur at the same time along different spatial locations and are then added together
Where in a neuron does the summation of EPSP or IPSP inputs happen?
At the axon hillock- this is where the cell assesses if the overall changes in charge bring it up to threshold
What are metabotropic receptors?
Another type of receptor that works much slower than ionotropic receptors but forms much more complex reactions
What are effector proteins?
Selectively binds to a protein to regulate its biological activity; can alter enzyme activity, gene expressionism, or other protein functions
Are metabotropic receptors ion channels?
No
What is the process by which metabotropic receptors are activated?
1). Binding of a neurotransmitter
2). Triggering the activation of the G proteins
3). Then the G proteins split into subunits which will then activate its own signal (effector) proteins
4). To modulate the channels, when the subunits bind to the channel it opens and allows an influx of ions
Or the G protein itself will bind to the channel and cause it to open
What is the metabotropic PKC pathway?
PKC stands for protein kinase C which is responsible for activating many important molecules by adding phosphate into them
Process of the metabotropic PKC pathway
1). Neurotransmitter binds to GPCR receptors which activate the G-protein subunits
2). The subunits then bind to the PLC (a membrane bound effector protein known as phospholipase C
3). This causes it to split into IP3 & DAG which will then (as a second messenger) impact\ other areas of the cell
How do potassium leak channels affect the voltage (charge) of the cell?
As they are always open, the positive potassium continually leaves the cell
True or False? The inside of the cell is often 60mV to 80mV more negative than the outside of the cell
True
What is resting membrane potential?
The electrical charge inside a neuron compared to the outside fluid when the neuron is at rest or not firing electrical signals
What is the inhibitory postsynaptic potential?
brief transiet hyperpolarization of the neuron as the mV becomes more negative
What are competitive agonists?
type of substance (agonist drug) that competes for the same binding site as the endogenous neurotransmitter but are much more concentrated
What are noncompetitive agonists?
- aka allosteric modulators
- increase the activity of the neurotransmitter without blocking the binding site which makes the neurotransmitter more effective
What is a second messenger and how does it relate to the Metabotropic PKC pathway?
A second messenger is a molecule, that is produced or activated by the effector protein, that diffuses away within the cystol to impact other areas of cell function.
In this case, IP3 and DAG are the second messengers of the pathway that are activated by the PLC which has PIP2 attached to it.
IP3 dissolves into the cystol to bind to specific ligond receptors (IP3-gated calcium channels) embedded in the membrane of the endoplasmic reticulum which causes calcium to flow into the cystol. The Calcim+ then binds to signaling molecules to cause effects leading to a cellular response.
While DAG stays bound to the membrane & activates protein kinase C (PKC) which then phosphorylates target protein which then causes a cellular response.
What are partial agonists?
Compete for the some binding site
- But have a smaller physiological effect on the receptor than endogenous neurotransmitter
Purpose of Prozac & Zoloft
- Treating mood disorders by inhibiting the function of reuptake transporter found in synapses that release the serotonin neurotransmitter
What is signal amplification?
process in which strength of a signal is increased after binding one molecule to a receptor
- the binding triggers a chain of events inside the cell that is also amplified
What is a reuptake transporter
featured in some presynaptic terminals
- It is a molecule that transports previously released neurotransmitter from the cleft bank into the presynaptic cell to be repackaged in vesicles and reused or degraded
How do SSRIs affect a person’s mood?
Because the reuptake transporters are blocked, the serotin hangs around the synaptic cleft giving it more time to have a bigger effect
What is agnoist drug?
a substance that binds to receptor and causes the same action as the substance (neurotransmitter) that normally binds to the receptor
- (neurotransmitter) these are known as endogenous or the naturally occurring neurotransmitter
Explain saltatory conduction
This is conduction down a myelinated neuron
_ It signals to be sent down the axon faster
Where does the name saltatory originate from & mean?
Originated from Latin word meaning “to jump”
How does the signal not degrade as it moves down the axon?
Sodium that has diffused into the axon because of AP causes the next set of sodium channels to open as that section of membrane reaches threshold. This process repeats, regenerating the AP. Only channels in front of the AP wave can open.
